REAR BICYCLE SPROCKET ARRANGEMENT AND BICYCLE DRIVETRAIN

Abstract

A rear bicycle sprocket assembly is configured for attachment to a sprocket support body of a rear bicycle hub assembly. The rear bicycle sprocket assembly includes a plurality of bicycle sprockets. The plurality of bicycle sprockets includes a first sprocket and a second sprocket. The first sprocket has a first opening with a first minimum diameter that is smaller than a minimum outer diameter of the sprocket support body of the rear bicycle hub assembly. The second sprocket has a second opening and at least ten internal splines. The second opening has a second minimum diameter that is equal to or greater than the minimum outer diameter of the sprocket support body of the rear bicycle hub assembly. The at least ten internal splines are configured to engage the sprocket support body of the rear bicycle hub assembly.

Description

BACKGROUND OF THE INVENTIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. patent application Nos. US 15 / 608,924 and US 15 / 608,915, filed on May 30, 2017, U.S. patent application Nos. US 15 / 673,346, filed on August 9, 2017, U.S. patent application Nos. US 15 / 686,177 and US 15 / 686,179, filed on August 25, 2017, U.S. patent application Nos. US 15 / 712,388 and US 15 / 712,407, filed on September 22, 2017, and U.S. patent application Nos. US 15 / 851,781 and US patent application Nos. 15 / 851,785, filed on December 22, 2017. The contents of these Applications are incorporated herein by reference in their entirety. FIELD OF THE INVENTION

[0002] The present invention relates to a bicycle rear sprocket assembly and a bicycle drivetrain. DISCUSSION OF THE BACKGROUND

[0003] Cycling is becoming an increasingly popular form of recreation as well as a means of transportation. Furthermore, cycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation, or competition, the bicycle industry is constantly improving the various components of the bicycle. One bicycle component that has undergone a significant redesign is the chainring assembly.

[0004] US 2012 / 0 244 978 A1 discloses a gear set connectable to a rotatable hub of a bicycle. The gear set includes a first gear, a second gear connected to the first gear, a support member disposed on the second gear, and at least one third gear connected to the second gear. US 2016 / 0 083 045 A1 shows a sprocket assembly and a sprocket device using the same, the sprocket device comprising a driver, a shift sleeve, a plurality of sprockets with different diameter sizes, a plurality of connectors, and a fastener. Therein, the driver is connected to a wheel hub of a rear wheel of a bicycle to transmit torque. One end of the shift sleeve is bolted to the driver.The sprockets, which are axially stacked from largest to smallest, are arranged in a direction from the driver to the shift sleeve, with sprockets arranged on the circumference of each sprocket for selectively engaging a chain. The annular connecting pieces are each coupled between two of the sprockets. The fastening element is screwed to the other end of the shift sleeve to fix the shift sleeve axially. DE 600 22 250 T2 shows a freewheel for attaching a plurality of sprockets to a bicycle axle. The freewheel essentially comprises an inner tubular body, an outer tubular body mounted coaxially on the inner tubular body, and a bearing assembly rotatably connecting the inner tubular body to the outer tubular body.A one-way clutch is coupled between the inner and outer tubular bodies to allow one-way rotation between the inner and outer tubular bodies. In the preferred embodiment, seven sprockets are mounted on the outside of the outer tubular body. The bearing assembly has a pair of ball bearing races of the same diameter at one end. An outer ball race or housing and side plate are used in conjunction with the inner tubular body to rigidly mount the first and second ball bearings to the outer surface of the inner tubular body. The inner tubular body with the bearings is then rigidly connected to the outer tubular body so that the outer tubular body can rotate relative to the inner tubular body. The one-way clutch includes a pair of pawls attached to the inner tubular body and a set of ratchet teeth formed on the inner tubular body.The locking teeth are rotated between the splines formed on the outer surface of the outer body. US 2008 / 0 188 336 A1 shows a bicycle sprocket device comprising a sprocket fastening member, a first sprocket, and a second sprocket. The sprocket fastening member comprises a hub fastening portion and a sprocket fastening portion, wherein the hub fastening portion is structured to be attachable to a rotating hub that rotates about a rotation axis. The sprocket fastening portion includes a first sprocket fastening surface facing in a first direction and a second sprocket fastening surface facing in an opposite second direction. The first sprocket is disposed on the first sprocket fastening surface, and the second sprocket is disposed on the second sprocket fastening surface.A fastening element fastens the first sprocket to the first sprocket mounting surface, and a chain support structure extends from the fastening element in the first direction and protrudes in the first direction away from a side surface of the first sprocket facing the first direction. DE 10 2015 005 141 A1 shows a bicycle hub assembly comprising a hub shaft, a hub shell, and a sprocket support member. The sprocket support member comprises a tubular portion and a first tooth. The tubular portion has an outer peripheral surface and a mounting portion provided just radially inward of the outer peripheral surface. The first tooth is configured to be attachable to the mounting portion of the tubular portion. The first tooth comprises a first surface and a second surface.The first surface is configured to face a mounting portion of a bicycle sprocket in a circumferential direction of the sprocket support member. The second surface is circumferentially opposite the first surface. The second surface is configured to face the mounting portion of the bicycle sprocket in the circumferential direction. SUMMARY OF THE INVENTION

[0005] The technical objective of the present application is to provide an improved rear sprocket assembly that allows for mounting smaller than conventional sprockets on a bicycle rear hub assembly.

[0006] To achieve this technical problem, according to the present invention, a rear bicycle sprocket assembly is configured for attachment to a sprocket support body of a rear bicycle hub assembly. The rear bicycle sprocket assembly comprises a plurality of bicycle sprockets. The plurality of bicycle sprockets comprises a first sprocket and a second sprocket. The first sprocket has a first opening with a first minimum diameter that is smaller than a minimum outer diameter of the sprocket support body of the rear bicycle hub assembly. The second sprocket has a second opening and at least ten internal splines or internal splines. The second opening has a second minimum diameter that is equal to or greater than the minimum outer diameter of the sprocket support body of the rear bicycle hub assembly.The at least ten internal splines are configured to engage the sprocket support body of the rear bicycle hub assembly. The rear bicycle sprocket assembly is configured such that the first sprocket has a first inward-facing side and a first outward-facing side opposite the first inward-facing side in an axial direction relative to a rotational center axis of the rear bicycle sprocket assembly. The first sprocket has a first torque-transmitting structure provided on the first inward-facing side for transmitting a pedaling torque directly or indirectly to the sprocket support body.

[0007] In the rear bicycle sprocket assembly according to the first aspect, the first minimum diameter allows the first sprocket to have a smaller pitch diameter. This enables a wider gear range of the rear bicycle sprocket assembly. Furthermore, the at least ten internal spline teeth of the second sprocket reduce a rotational force applied to each of the at least ten internal spline teeth compared to a sprocket with nine or fewer internal spline teeth. This improves the durability of the second sprocket and / or improves a degree of freedom in selecting a material of the second sprocket without reducing the durability of the second sprocket. Furthermore, in the rear bicycle sprocket assembly according to the first aspect, it is possible to attach a smaller sprocket to the rear bicycle hub assembly. This enables a wider gear range of the rear bicycle sprocket assembly.

[0008] Further advantageous embodiments will become apparent from the appended subordinate patent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. Fig. 1 is a schematic diagram of a bicycle drivetrain according to one embodiment. Fig. 2 is an exploded perspective view of the bicycle drive train shown in Fig. 1 is shown. Fig. 3 is a cross-sectional view of the bicycle drive train taken along line III-III of Fig. 2. Fig. 4 is a perspective view of a rear bicycle hub assembly of the Fig. 2 illustrated bicycle drivetrain with a locking element of a rear bicycle sprocket assembly. Fig. 5 is a side elevational view of the rear bicycle sprocket assembly of the Fig. 1 illustrated bicycle drivetrain. Fig. 6 is an enlarged cross-sectional view of the Fig. 4 illustrated bicycle drivetrain. Fig. 7 is a side elevation view of a sprocket of the Fig. 5 shown rear wheel arrangement. Fig. 8 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 9 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 10 is a side elevational view of a first sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 11 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 12 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 13 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 14 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 15 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 16 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 17 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 18 is a side elevation view of a sprocket of the Fig. 5 rear bicycle sprocket arrangement. Fig. 19 is an exploded perspective view of the Fig. 5 rear bicycle sprocket arrangement. Fig. 20 is a perspective view of a sprocket support body of the Fig. 4 rear bicycle hub arrangement. Fig. 21 is another perspective view of the sprocket support body of the Fig. 4 rear bicycle hub arrangement. Fig. 22 is a rear view of the sprocket support body of the Fig. 4 rear bicycle hub arrangement. Fig. 23 is a side elevational view of the sprocket support body of the Fig. 4 rear bicycle hub arrangement. Fig. 24 is a side elevational view of the sprocket support body of the rear bicycle hub assembly according to a modification. Fig. 25 is an enlarged cross-sectional view of the Fig. 23 shown bicycle support body. Fig. 26 is a cross-sectional view of the Fig. 23 shown bicycle support body. Fig. 27 is a perspective view of the Fig. 4 rear bicycle hub arrangement. Fig. 28 is a side elevation view of the Fig. 4 rear bicycle hub arrangement. Fig. 29 is a rear view of the in Fig. 4 rear bicycle hub arrangement. Fig. 30 is an exploded perspective view of a sprocket support body and several spacers of the Fig. 4 rear bicycle hub arrangement. Fig. 31 is a partially enlarged cross-sectional view of the Fig. 4 illustrated bicycle drivetrain. Fig. 32 is another side elevation view of the Fig. 8 shown sprocket. Fig. 33 is a side elevation view of the Fig. 9 shown sprocket. Fig. 34 is a side elevation view of the Fig. 9 shown sprocket according to a modification. Fig. 35 is an enlarged cross-sectional view of the Fig. 29 shown sprocket. Fig. 36 is another cross-sectional view of the Fig. 29 shown sprocket. Fig. 37 is another cross-sectional view of the Fig. 2 illustrated bicycle drivetrain. Fig. 38 is an exploded perspective view of the Fig. 7 and Fig. 8 sprockets shown. Fig. 39 is another exploded perspective view of the Fig. 7 and Fig. 8 sprockets shown. Fig. 40 is an exploded perspective view of a portion of the Fig. 4 rear bicycle hub arrangement. Fig. 41 is an exploded perspective view of a portion of the Fig. 40 rear bicycle hub assembly shown. Fig. 42 is an exploded perspective view of a portion of the Fig. 40 rear bicycle hub assembly shown. Fig. 43 is an exploded perspective view of a portion of the Fig. 40 rear bicycle hub assembly shown. Fig. 44 is a partial cross-sectional view of the Fig. 40 rear bicycle hub assembly shown. Fig. 45 is a cross-sectional view of the rear bicycle hub assembly taken along line XLV-XLV of Fig. 44. Fig. 46 is a perspective view of a spacer of the Fig. 40 rear bicycle hub assembly shown. Fig. 47 is another perspective view of a spacer of the Fig. 40 rear bicycle hub assembly shown. Fig. 48 is a schematic diagram showing an action of a first pawl member and a sprocket support body of the Fig. 40 shows the rear bicycle hub arrangement (pedal operation). Fig. 49 is a schematic diagram showing an action of a first pawl member and a sprocket support body of the Fig. 40 shows the rear bicycle hub arrangement (rolling out). Fig. 50 is an enlarged cross-sectional view of the sprocket support body according to a modification. Fig. 51 is an enlarged cross-sectional view of the sprocket according to a modification. Fig. 52 is a side elevational view of a sprocket support body of a rear bicycle hub assembly according to a modification. Fig. 53 is an enlarged cross-sectional view of a Fig. 52 shown sprocket support body. Fig. 54 is an exploded perspective view of sprockets of a bicycle rear sprocket assembly according to a modification. Fig. 55 is another exploded perspective view of the sprockets of the bicycle rear sprocket assembly according to the modification. Fig. 56 is a side elevational view of a sprocket of the bicycle rear sprocket assembly according to the modification. Fig. 57 is a side elevational view of a sprocket of the bicycle rear sprocket assembly according to the modification. Fig. 58 is a side elevational view of a sprocket of the bicycle rear sprocket assembly according to the modification. Fig. 59 is a side elevation view of the Fig. 57 shown sprocket. Fig. 60 is an enlarged cross-sectional view of the Fig. 57 shown sprocket. Fig. 61 is a partial side elevational view of a sprocket support member of the bicycle rear sprocket assembly according to the modification. Fig. 62 is a cross-sectional view of a bicycle drive train according to a modification. DESCRIPTION OF THE EMBODIMENTS

[0010] The embodiment(s) will now be described with reference to the accompanying drawings, in which like reference numerals designate corresponding or identical elements throughout the various drawings. It should be noted that those portions of the following description relating to the precise configuration of a sprocket, including gear shifting ranges and tooth counts, as well as the axle bushing or brake body of a rear bicycle hub assembly, are not to be considered part of the present invention. They are provided merely to facilitate understanding of the subject matter described below.

[0011] With initial reference to Fig. 1, a bicycle drivetrain 10 according to one embodiment includes a rear bicycle hub assembly 12 and a rear bicycle sprocket assembly 14. The rear bicycle hub assembly 12 is attached to a bicycle frame BF. The rear bicycle sprocket assembly 14 is attached to the rear bicycle hub assembly 12. A bicycle brake rotor 16 is attached to the rear bicycle hub assembly 12.

[0012] The bicycle drivetrain 10 further includes a crank assembly 18 and a bicycle chain 20. The crank assembly 18 includes a crankshaft 22, a right crank arm 24, a left crank arm 26, and a front sprocket 27. The right crank arm 24 and the left crank arm 26 are attached to the crank axle 22. The front sprocket 27 is attached to at least one of the crank axle 22 and the right crank arm 24. The bicycle chain 20 engages the front sprocket 27 and the rear bicycle sprocket assembly 14 to transmit a pedaling force from the front sprocket 27 to the rear bicycle sprocket assembly 14. The crank assembly 18 includes the front sprocket 27 as a single sprocket in the illustrated embodiment. However, the crank assembly 18 may include multiple front sprockets. The rear bicycle sprocket assembly 14 is a rear sprocket assembly.However, structures of the rear bicycle sprocket assembly 14 can also be applied to the front sprocket.

[0013] In the present application, the following directional terms "front," "rear," "forward," "backward," "left," "right," "across," "upward," and "downward," and other similar directional designations refer to those directions determined based on a user (e.g., a rider) sitting on a saddle (not shown) of a bicycle facing a handlebar (not shown). Accordingly, as used to describe the bicycle drivetrain 10, the rear bicycle hub assembly 12, or the rear bicycle sprocket assembly 14, these terms should be interpreted with respect to the bicycle equipped with the bicycle drivetrain 10, the rear bicycle hub assembly 12, or the rear bicycle sprocket assembly 14 as used in an upright riding position on a horizontal surface.

[0014] As in Fig. 2, the rear bicycle hub assembly 12 and the rear bicycle sprocket assembly 14 comprise a rotational center axis A1. The rear bicycle sprocket assembly 14 is defined by the rear bicycle hub assembly 12 with respect to the bicycle frame BF ( Fig. 1) is rotatably supported about the rotational center axis A1. The rear bicycle sprocket assembly 14 is configured to engage the bicycle chain 20 to transmit a driving rotational force F1 between the bicycle chain 20 and the rear bicycle sprocket assembly 14 during pedaling. The rear bicycle sprocket assembly 14 is rotated about the rotational center axis A1 in a driving rotational direction D11 during pedaling. The driving rotational direction D11 is defined along a circumferential direction D1 of the rear bicycle hub assembly 12 or the rear bicycle sprocket assembly 14. An opposite rotational direction D12 is an opposite direction of the driving rotational direction D11 and is defined along the circumferential direction D1.

[0015] As in Fig. As seen in Figure 2, the rear bicycle hub assembly 12 includes a sprocket support body 28. The rear bicycle sprocket assembly 14 is configured to be attached to the sprocket support body 28 of the rear bicycle hub assembly 12. The rear bicycle sprocket assembly 14 is attached to the sprocket support body 28 to transmit the driving rotational force F1 between the sprocket support body 28 and the rear bicycle sprocket assembly 14. The rear bicycle hub assembly 12 includes a hub axle 30. The sprocket support body 28 is rotatably attached to the hub axle 30 about the rotational center axis A1. The rear bicycle sprocket assembly 14 further includes a locking member 32. The locking member 32 is attached to the sprocket support body 28 to hold the rear bicycle sprocket assembly 14 relative to the sprocket support body 28 in an axial direction D2 with respect to the rotational center axis A1.

[0016] As in Fig. As shown in Figure 3, the rear bicycle hub assembly 12 is attached to the bicycle frame BF with a wheel attachment structure WS. The hub axle 30 includes an axle through-bore 30A. A mounting rod WS1 of the wheel attachment structure WS extends through the axle through-bore 30A of the hub axle 30. The hub axle 30 includes a first axle end 30B and a second axle end 30C. The hub axle 30 extends between the first axle end 30B and the second axle end 30C along the rotational center axis A1. The first axle end 30B is provided in a first recess BF11 of a first frame BF1 of the bicycle frame BF. The second axle end 30C is provided in a second recess BF21 of a second frame BF2 of the bicycle frame BF. The hub axle 30 is held between the first frame BF1 and the second frame BF2 by the wheel mounting structure WS. The wheel mounting structure WS comprises a structure known in the bicycle field.Therefore, for the sake of brevity, it will not be described in detail here.

[0017] In this embodiment, the axle through-bore 30A has a minimum inner diameter BD1 equal to or greater than 13 mm. The minimum inner diameter BD1 of the axle through-bore 30A is preferably equal to or greater than 14 mm. The minimum inner diameter BD1 of the axle through-bore 30A is preferably equal to or less than 21 mm. In this embodiment, the minimum inner diameter BD1 of the axle through-bore 30A is 15 mm. However, the minimum inner diameter BD1 is not limited to this embodiment and the above ranges.

[0018] The hub axle 30 includes a maximum outer diameter BD2 that is equal to or greater than 17 mm. The maximum outer diameter BD2 of the hub axle 30 is preferably equal to or greater than 20 mm. The maximum outer diameter BD2 of the hub axle 30 is preferably equal to or less than 23 mm. In this embodiment, the maximum outer diameter BD2 of the hub axle 30 is 21 mm. However, the maximum outer diameter BD2 of the hub axle 30 is not limited to this embodiment and the above ranges. The hub axle 30 includes a minimum outer diameter BD3 that is equal to or greater than 15 mm. The minimum outer diameter BD3 is preferably equal to or greater than 17 mm. The minimum outer diameter BD3 is preferably equal to or less than 19 mm. In this embodiment, the minimum outer diameter BD3 of the hub axle 30 is 17.6 mm.However, the minimum outer diameter BD3 is not limited to this embodiment and the above ranges.

[0019] The hub axle 30 includes an axle tube 30X, a first axle portion 30Y, and a second axle portion 30Z. The axle tube 30X has a tubular shape and extends along the rotational center axis A1. The first axle portion 30Y is fixed to a first end of the axle tube 30X. The second axle portion 30Z is fixed to a second end of the axle tube 30X. At least one of the first axle portion 30Y and the second axle portion 30Z may be integrally formed with the axle tube 30X.

[0020] As seen in Figures 3 and 4, the rear bicycle hub assembly 12 further includes a brake rotor support body 34. The brake rotor support body 34 is rotatably mounted on the hub axle 30 about the rotational center axis A1. The brake rotor support body 34 is connected to the bicycle brake rotor 16 ( Fig. 1) to transmit a braking torque from the bicycle brake rotor 16 to the brake rotor support body 34.

[0021] As in Fig. 4, the rear bicycle hub assembly 12 includes a hub body 36. The hub body 36 is rotatably mounted to the hub axle 30 about the rotational center axis A1 of the rear bicycle hub assembly 12. In this embodiment, the sprocket support body 28 is a separate member from the hub body 36. The brake rotor support body 34 is provided integrally with the hub body 36 as a one-piece unitary member. However, the sprocket support body 28 may be provided integrally with the hub body 36. The brake rotor support body 34 may be a separate member from the hub body 36. The hub body 36 is made, for example, of a metallic material including aluminum.

[0022] As in Fig. 5, the rear bicycle sprocket assembly 14 includes a plurality of bicycle sprockets. The plurality of bicycle sprockets includes a first sprocket and a second sprocket. In this embodiment, the plurality of bicycle sprockets includes a plurality of first sprockets SP1 and SP2 provided as the first sprocket. The plurality of bicycle sprockets also includes a plurality of second sprockets SP3 and SP4 provided as the second sprocket. The plurality of bicycle sprockets includes an additional sprocket. In this embodiment, the plurality of bicycle sprockets includes a plurality of additional sprockets SP5 to SP12. However, the total number of first sprockets is not limited to this embodiment. The total number of second sprockets is not limited to this embodiment. The total number of additional sprockets is not limited to this embodiment.Furthermore, the first sprockets SP1 and SP2 may be integrally formed as a one-piece unitary member, while the first sprocket SP1 in this embodiment is a separate sprocket from the first sprocket SP2. Similarly, the second sprockets SP3 and SP4 may be integrally formed as a one-piece unitary member, while in this embodiment the second sprocket SP3 is a separate sprocket from the second sprocket SP4.

[0023] For example, a total number of the plurality of bicycle sprockets is equal to or greater than 10. The total number of the plurality of bicycle sprockets may be equal to or greater than 11. The total number of the plurality of bicycle sprockets may be equal to or greater than 12. In this embodiment, the total number of bicycle sprockets is 12. However, the total number of bicycle sprockets is not limited to this embodiment. For example, the total number of the plurality of bicycle sprockets may be 13, 14, or equal to or greater than 15.

[0024] In this embodiment, the first sprocket SP1 is the smallest sprocket in the rear bicycle sprocket assembly 14. The additional sprocket SP12 is the largest sprocket in the rear bicycle sprocket assembly 14. The first sprocket SP2 corresponds to the highest gear in the rear bicycle sprocket assembly 14. The additional sprocket SP12 corresponds to a low gear in the rear bicycle sprocket assembly 14.

[0025] As in Fig. As can be seen in Figure 5, the first sprocket SP1 has a pitch circle diameter PCD1. The first sprocket SP2 has a pitch circle diameter PCD2. The second sprocket SP3 has a pitch circle diameter PCD3. The second sprocket SP4 has a pitch circle diameter PCD4. The additional sprocket SP5 has a pitch circle diameter PCD5. The additional sprocket SP6 has a pitch circle diameter PCD6. The additional sprocket SP7 has a pitch circle diameter PCD7. The additional sprocket SP8 has a pitch circle diameter PCD8. The additional sprocket SP9 has a pitch circle diameter PCD9. The additional sprocket SP10 has a pitch circle diameter PCD10. The additional sprocket SP11 has a pitch circle diameter PCD11. The additional sprocket SP12 has a pitch circle diameter PCD12.

[0026] The first sprocket SP1 has a pitch circle PC1 with a pitch circle diameter PCD1. The first sprocket SP2 has a pitch circle PC2 with a pitch circle diameter PCD2. The second sprocket SP3 has a pitch circle PC3 with a pitch circle diameter PCD3. The second sprocket SP4 has a pitch circle PC4 with a pitch circle diameter PCD4. The additional sprocket SP5 has a pitch circle PC5 with a pitch circle diameter PCD5. The additional sprocket SP6 has a pitch circle PC6 with a pitch circle diameter PCD6. The additional sprocket SP7 has a pitch circle PC7 with a pitch circle diameter PCD7. The additional sprocket SP8 has a pitch circle PC8 with a pitch circle diameter PCD8. The additional sprocket SP9 has a pitch circle PC9 with a pitch circle diameter PCD9. The additional sprocket SP10 has a pitch circle PC10 with a pitch circle diameter PCD10.The additional sprocket SP11 has a pitch circle PC11 with a pitch circle diameter PCD11. The additional sprocket SP12 has a pitch circle PC12 with a pitch circle diameter PCD12.

[0027] The pitch circle PC1 of the first chain wheel SP1 is defined by the center axes of the pins of the bicycle chain 20 ( Fig. 2) that mesh with the first sprocket SP1. The pitch circles PC2 to PC12 are defined in the same way as the pitch circle PC1. Therefore, for the sake of brevity, they will not be described in detail here.

[0028] In this embodiment, the pitch circle diameter PCD1 is smaller than the pitch circle diameter PCD2. The pitch circle diameter PCD2 is smaller than the pitch circle diameter PCD3. The pitch circle diameter PCD3 is smaller than the pitch circle diameter PCD4. The pitch circle diameter PCD4 is smaller than the pitch circle diameter PCD5. The pitch circle diameter PCD5 is smaller than the pitch circle diameter PCD6. The pitch circle diameter PCD6 is smaller than the pitch circle diameter PCD7. The pitch circle diameter PCD7 is smaller than the pitch circle diameter PCD8. The pitch circle diameter PCD8 is smaller than the pitch circle diameter PCD9. The pitch circle diameter PCD9 is smaller than the pitch circle diameter PCD10. The pitch circle diameter PCD10 is smaller than the pitch circle diameter PCD11. The pitch circle diameter PCD11 is smaller than the pitch circle diameter PCD12.

[0029] The pitch circle diameter PCD1 is the smallest pitch circle diameter in the rear bicycle sprocket assembly 14. The pitch circle diameter PCD12 is the largest pitch circle diameter in the rear bicycle sprocket assembly 14. The first sprocket SP1 corresponds to a high gear in the bicycle sprocket assembly 14. The additional sprocket SP12 corresponds to a low gear in the rear bicycle sprocket assembly 14. However, the first sprocket SP1 may correspond to a different gear in the rear bicycle sprocket assembly 14. The additional sprocket SP12 may correspond to a different gear in the rear bicycle sprocket assembly 14.

[0030] As in Fig. 6, the first sprocket SP2 is adjacent to the first sprocket SP1 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the first sprockets SP1 and SP2. The second sprocket SP3 is adjacent to the first sprocket SP2 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the first sprocket SP2 and the second sprocket SP3. The second sprocket SP4 is adjacent to the second sprocket SP3 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the second sprocket SP3 and the second sprocket SP4. The first sprockets SP1 and SP2, the second sprocket SP3, the second sprocket SP4, and the additional sprockets SP5 to SP12 are arranged in this order in the axial direction D2.

[0031] As in Fig. As seen in Figure 7, the first sprocket SP1 includes a sprocket body SP1A and a plurality of sprocket teeth SP1B. The plurality of sprocket teeth SP1B extend radially outward from the sprocket body SP1A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. A total number of teeth of the first sprocket SP1 (a total number of the at least one sprocket tooth SP1B) is equal to or less than 10. In this embodiment, the total number of the at least one sprocket tooth SP1B of the first sprocket SP1 is 10. However, the total number of the plurality of sprocket teeth SP1B of the first sprocket SP1 is not limited to this embodiment and the above range.

[0032] As in Fig. As seen in Figure 8, the first sprocket SP2 includes a sprocket body SP2A and a plurality of sprocket teeth SP2B. The plurality of sprocket teeth SP2B extend radially outward from the sprocket body SP2A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP2B is 12. However, the total number of the plurality of sprocket teeth SP2B of the first sprocket SP2 is not limited to this embodiment.

[0033] The first sprocket SP2 includes at least one first shifting-promoting region SP2F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the first sprocket SP2 to the first sprocket SP1. The first sprocket SP2 includes at least one second shifting-promoting region SP2F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the first sprocket SP1 to the first sprocket SP2. In this embodiment, the first sprocket SP2 includes a plurality of first shifting-promoting regions SP2F1 to facilitate the first shifting operation. The first sprocket SP2 includes a second shifting-promoting region SP2F2 to facilitate the second shifting operation. However, a total number of the first shifting-promoting regions SP2F1 is not limited to this embodiment. A total number of the second shifting-promoting region SP2F2 is not limited to this embodiment.The term “shift facilitating region” as used herein is intended to be a region intentionally designed to facilitate a shifting operation of a bicycle chain from one sprocket to another axially adjacent sprocket in the region.

[0034] In this embodiment, the first sprocket SP2 includes a plurality of first shifting-promoting recesses SP2R1 to facilitate the first shifting operation. The first sprocket SP2 includes a plurality of second shifting-promoting recesses SP2R2 to facilitate the second shifting operation. The first shifting-promoting recess SP2R1 is provided in the first shifting-promoting region SP2F1. However, the first shifting-promoting region SP2F1 may include another structure instead of or in addition to the first shifting-promoting recess SP2R1. The second shifting-promoting region SP2F2 may include another structure instead of or in addition to the second shifting-promoting recess SP2R2.

[0035] As in Fig. As seen in Figure 9, the second sprocket SP3 includes a sprocket body SP3A and a plurality of sprocket teeth SP3B. The plurality of sprocket teeth SP3B extend radially outward from the sprocket body SP3A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP3B is 14. The total number of the plurality of sprocket teeth SP3B of the second sprocket SP3 is not limited to this embodiment.

[0036] The second sprocket SP3 comprises at least one first shifting promotion area SP3F1 to facilitate a first shifting operation in which the bicycle chain 20 is shifted from the second sprocket SP3 to the first sprocket SP2 ( Fig. 6). The second sprocket SP3 comprises at least one second shifting assistance area SP3F2 to facilitate a second shifting operation in which the bicycle chain 20 is disengaged from the first sprocket SP2 ( Fig. 6) switches to the second sprocket SP3. In this embodiment, the second sprocket SP3 includes a plurality of first shift facilitating regions SP3F1 to facilitate the first shifting operation. The second sprocket SP3 includes a second shift facilitating region SP3F2 to facilitate the second shifting operation. However, a total number of the first shift facilitating regions SP3F1 is not limited to this embodiment. A total number of the second shift facilitating regions SP3F2 is not limited to this embodiment.

[0037] In this embodiment, the second sprocket SP3 includes a plurality of first shifting promotion recesses SP3R1 to facilitate the first shifting operation. The second sprocket SP3 includes a plurality of second shifting promotion recesses SP3R2 to facilitate the second shifting operation. The first shifting promotion recess SP3R1 is provided in the first shifting promotion region SP3F1. However, the first shifting promotion region SP3F1 may include another structure instead of or in addition to the first shifting promotion recess SP3R1. The second shifting promotion region SP3F2 may include another structure instead of or in addition to the second shifting promotion recess SP3R2.

[0038] As in Fig. As shown in Figure 10, the second sprocket SP4 includes a sprocket body SP4A and a plurality of sprocket teeth SP4B. The plurality of sprocket teeth SP4B extend radially outward from the sprocket body SP4A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP4B is 16. However, the total number of the plurality of sprocket teeth SP4B of the second sprocket SP4 is not limited to this embodiment.

[0039] The second sprocket SP4 includes at least one first shifting promotion region SP4F1 to facilitate a first shifting operation in which the bicycle chain 20 switches from the second sprocket SP4 to the second sprocket SP3. The second sprocket SP4 includes at least one second shifting promotion region SP4F2 to facilitate a second shifting operation in which the bicycle chain 20 switches from the second sprocket SP3 to the second sprocket SP4. In this embodiment, the second sprocket SP4 includes a plurality of first shifting promotion regions SP4F1 to facilitate the first shifting operation. The second sprocket SP4 includes a second shifting promotion region SP4F2 to facilitate the second shifting operation. However, a total number of the first shifting promotion regions SP4F1 is not limited to this embodiment. A total number of the second shifting promotion regions SP4F2 is not limited to this embodiment.

[0040] In this embodiment, the second sprocket SP4 includes a plurality of first shifting promotion recesses SP4R1 to facilitate the first shifting operation. The second sprocket SP4 includes a plurality of second shifting promotion recesses SP4R2 to facilitate the second shifting operation. The first shifting promotion recess SP4R1 is provided in the first shifting promotion region SP4F1. However, the first shifting promotion region SP4F1 may include another structure instead of or in addition to the first shifting promotion recess SP4R1. The second shifting promotion region SP4F2 may include another structure instead of or in addition to the second shifting promotion recess SP4R2.

[0041] As in Fig. As shown in Figure 11, the additional sprocket SP5 includes a sprocket body SP5A and a plurality of sprocket teeth SP5B. The plurality of sprocket teeth SP5B extend radially outward from the sprocket body SP5A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP5B is 18. However, the total number of the plurality of sprocket teeth SP5B of the additional sprocket SP5 is not limited to this embodiment.

[0042] The additional sprocket SP5 includes at least one first shifting-promoting region SP5F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the additional sprocket SP5 to the adjacent smaller sprocket SP4. The additional sprocket SP5 includes at least one second shifting-promoting region SP5F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the adjacent smaller sprocket SP4 to the additional sprocket SP5. The adjacent smaller sprocket SP4 is adjacent to the additional sprocket SP5 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP5 and the adjacent smaller sprocket SP4. In this embodiment, the additional sprocket SP5 includes a plurality of first shifting-promoting regions SP5F1 to facilitate the first shifting operation.The additional sprocket SP5 includes a plurality of second shifting support sections SP5F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP5F1 is not limited to this embodiment. The total number of the second shifting support sections SP5F2 is not limited to this embodiment.

[0043] In this embodiment, the additional sprocket SP5 includes a plurality of first shifting conveyance recesses SP5R1 to facilitate the first shifting operation. The additional sprocket SP5 includes a plurality of second shifting conveyance recesses SP5R2 to facilitate the second shifting operation. The first shifting conveyance recess SP5R1 is provided in the first shifting conveyance region SP5F1. The second shifting conveyance recess SP5R2 is provided in the second shifting conveyance region SP5F2. However, the first shifting conveyance region SP5F1 may include another structure instead of or in addition to the first shifting conveyance recess SP5R1. The second shifting conveyance region SP5F2 may include another structure instead of or in addition to the second shifting conveyance recess SP5R2.

[0044] As in Fig. As shown in Figure 12, the additional sprocket SP6 includes a sprocket body SP6A and a plurality of sprocket teeth SP6B. The plurality of sprocket teeth SP6B extend radially outward from the sprocket body SP6A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP6B is 21. However, the total number of the plurality of sprocket teeth SP6B of the additional sprocket SP6 is not limited to this embodiment.

[0045] The additional sprocket SP6 includes at least one first shifting advancement region SP6F1 to facilitate a first shifting operation in which the bicycle chain 20 moves from the additional sprocket SP6 to the adjacent smaller sprocket SP5. The additional sprocket SP6 includes at least one second shifting advancement region SP6F2 to facilitate a second shifting operation in which the bicycle chain 20 moves from the adjacent smaller sprocket SP5 to the additional sprocket SP6. The adjacent smaller sprocket SP5 is adjacent to the additional sprocket SP6 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP6 and the adjacent smaller sprocket SP5. In this embodiment, the additional sprocket SP6 includes a plurality of first shifting advancement regions SP6F1 to facilitate the first shifting operation.The additional sprocket SP6 includes a plurality of second shifting support sections SP6F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP6F1 is not limited to this embodiment. The total number of the second shifting support sections SP6F2 is not limited to this embodiment.

[0046] In this embodiment, the additional sprocket SP6 includes a plurality of first shifting promotion recesses SP6R1 to facilitate the first shifting operation. The additional sprocket SP6 has a plurality of second shifting promotion recesses SP6R2 to facilitate the second shifting operation. The first shifting promotion recess SP6R1 is provided in the first shifting promotion region SP6F1. The second shifting promotion recess SP6R2 is provided in the second shifting promotion region SP6F2. However, the first shifting promotion region SP6F1 may include another structure instead of or in addition to the first shifting promotion recess SP6R1. The second shifting promotion region SP6F2 may include another structure instead of or in addition to the second shifting promotion recess SP6R2.

[0047] As in Fig. As shown in Figure 13, the additional sprocket SP7 includes a sprocket body SP7A and a plurality of sprocket teeth SP7B. The plurality of sprocket teeth SP7B extend radially outward from the sprocket body SP7A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP7B is 24. However, the total number of the plurality of sprocket teeth SP7B of the additional sprocket SP7 is not limited to this embodiment.

[0048] The additional sprocket SP7 includes at least one first shifting-promoting region SP7F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the additional sprocket SP7 to the adjacent smaller sprocket SP6. The additional sprocket SP7 includes at least one second shifting-promoting region SP7F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the adjacent smaller sprocket SP6 to the additional sprocket SP7. The adjacent smaller sprocket SP6 is adjacent to the additional sprocket SP7 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP7 and the adjacent smaller sprocket SP6. In this embodiment, the additional sprocket SP7 includes a plurality of first shifting-promoting regions SP7F1 to facilitate the first shifting operation.The additional sprocket SP7 includes a plurality of second shifting support sections SP7F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP7F1 is not limited to this embodiment. The total number of the second shifting support sections SP7F2 is not limited to this embodiment.

[0049] In this embodiment, the additional sprocket SP7 includes a plurality of first shifting conveyance recesses SP7R1 to facilitate the first shifting operation. The additional sprocket SP7 includes a plurality of second shifting conveyance recesses SP7R2 to facilitate the second shifting operation. The first shifting conveyance recess SP7R1 is provided in the first shifting conveyance region SP7F1. The second shifting conveyance recess SP7R2 is provided in the second shifting conveyance region SP7F2. However, the first shifting conveyance region SP7F1 may have a different structure instead of or in addition to the first shifting conveyance recess SP7R1. The second shifting conveyance region SP7F2 may have a different structure instead of or in addition to the second shifting conveyance recess SP7R2.

[0050] As in Fig. As shown in Figure 14, the additional sprocket SP8 includes a sprocket body SP8A and a plurality of sprocket teeth SP8B. The plurality of sprocket teeth SP8B extend radially outward from the sprocket body SP8A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP8B is 28. However, the total number of the plurality of sprocket teeth SP8B of the additional sprocket SP8 is not limited to this embodiment.

[0051] The additional sprocket SP8 includes at least one first shifting promotion region SP8F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the additional sprocket SP8 to the adjacent smaller sprocket SP7. The additional sprocket SP8 includes at least one second shifting promotion region SP8F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the adjacent smaller sprocket SP7 to the additional sprocket SP8. The adjacent smaller sprocket SP7 is adjacent to the additional sprocket SP8 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP8 and the adjacent smaller sprocket SP7. In this embodiment, the additional sprocket SP8 includes a plurality of first shifting promotion regions SP8F1 to facilitate the first shifting operation.The additional sprocket SP8 includes a plurality of second shifting support sections SP8F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP8F1 is not limited to this embodiment. The total number of the second shifting support sections SP8F2 is not limited to this embodiment.

[0052] In this embodiment, the additional sprocket SP8 includes a plurality of first shifting promotion recesses SP8R1 to facilitate the first shifting operation. The additional sprocket SP8 includes a plurality of second shifting promotion recesses SP8R2 to facilitate the second shifting operation. The first shifting promotion recess SP8R1 is provided in the first shifting promotion region SP8F1. The second shifting promotion recess SP8R2 is provided in the second shifting promotion region SP8F2. However, the first shifting promotion region SP8F1 may have a different structure instead of or in addition to the first shifting promotion recess SP8R1. The second shifting promotion region SP8F2 may have a different structure instead of or in addition to the second shifting promotion recess SP8R2.

[0053] As in Fig. As shown in Figure 15, the additional sprocket SP9 includes a sprocket body SP9A and a plurality of sprocket teeth SP9B. The plurality of sprocket teeth SP9B extend radially outward from the sprocket body SP9A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP9B is 33. However, the total number of the plurality of sprocket teeth SP9B of the additional sprocket SP9 is not limited to this embodiment.

[0054] The additional sprocket SP9 includes at least one first shifting assistance region SP9F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the additional sprocket SP9 to the adjacent smaller sprocket SP8. The additional sprocket SP9 includes at least one second shifting assistance region SP9F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the adjacent smaller sprocket SP8 to the additional sprocket SP9. The adjacent smaller sprocket SP8 is adjacent to the additional sprocket SP9 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP9 and the adjacent smaller sprocket SP8. In this embodiment, the additional sprocket SP9 includes a plurality of first shifting assistance regions SP9F1 to facilitate the first shifting operation.The additional sprocket SP9 includes a plurality of second shifting support sections SP9F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP9F1 is not limited to this embodiment. The total number of the second shifting support sections SP9F2 is not limited to this embodiment.

[0055] In this embodiment, the additional sprocket SP9 includes a plurality of first shifting conveyance recesses SP9R1 to facilitate the first shifting operation. The additional sprocket SP9 includes a plurality of second shifting conveyance recesses SP9R2 to facilitate the second shifting operation. The first shifting conveyance recess SP9R1 is provided in the first shifting conveyance region SP9F1. The second shifting conveyance recess SP9R2 is provided in the second shifting conveyance region SP9F2. However, the first shifting conveyance region SP9F1 may have a different structure instead of or in addition to the first shifting conveyance recess SP9R1. The second shifting conveyance region SP9F2 may have a different structure instead of or in addition to the second shifting conveyance recess SP9R2.

[0056] As in Fig. As shown in Figure 16, the additional sprocket SP10 includes a sprocket body SP10A and a plurality of sprocket teeth SP10B. The plurality of sprocket teeth SP10B extend radially outward from the sprocket body SP10A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP10B is 39. However, the total number of the plurality of sprocket teeth SP10B of the additional sprocket SP10 is not limited to this embodiment.

[0057] The additional sprocket SP10 includes at least one first shifting assistance region SP10F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the additional sprocket SP10 to the adjacent smaller sprocket SP9. The additional sprocket SP10 includes at least one second shifting assistance region SP10F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the adjacent smaller sprocket SP9 to the additional sprocket SP10. The adjacent smaller sprocket SP9 is adjacent to the additional sprocket SP10 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP10 and the adjacent smaller sprocket SP9. In this embodiment, the additional sprocket SP10 includes a plurality of first shifting assistance regions SP10F1 to facilitate the first shifting operation.The additional sprocket SP10 includes a plurality of second shifting support sections SP10F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP10F1 is not limited to this embodiment. The total number of the second shifting support sections SP10F2 is not limited to this embodiment.

[0058] In this embodiment, the additional sprocket SP10 includes a plurality of first shifting promotion recesses SP10R1 to facilitate the first shifting operation. The additional sprocket SP10 includes a plurality of second shifting promotion recesses SP10R2 to facilitate the second shifting operation. The first shifting promotion recess SP10R1 is provided in the first shifting promotion region SP10F1. The second shifting promotion recess SP10R2 is provided in the second shifting promotion region SP10F2. However, the first shifting promotion region SP10F1 may have a different structure instead of or in addition to the first shifting promotion recess SP10R1. The second shifting promotion region SP10F2 may have a different structure instead of or in addition to the second shifting promotion recess SP10R2.

[0059] As in Fig. As shown in Figure 17, the additional sprocket SP11 includes a sprocket body SP11A and a plurality of sprocket teeth SP11B. The plurality of sprocket teeth SP11B extend radially outward from the sprocket body SP11A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. In this embodiment, a total number of the at least one sprocket tooth SP11B is 45. However, the total number of the plurality of sprocket teeth SP11B of the additional sprocket SP11 is not limited to this embodiment.

[0060] The additional sprocket SP11 includes at least one first shifting promotion region SP11F1 to facilitate a first shifting operation in which the bicycle chain 20 changes from the additional sprocket SP11 to the adjacent smaller sprocket SP10. The additional sprocket SP11 includes at least one second shifting promotion region SP11F2 to facilitate a second shifting operation in which the bicycle chain 20 changes from the adjacent smaller sprocket SP10 to the additional sprocket SP11. The adjacent smaller sprocket SP10 is adjacent to the additional sprocket SP11 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP11 and the adjacent smaller sprocket SP10. In this embodiment, the additional sprocket SP11 includes a plurality of first shifting promotion regions SP11F1 to facilitate the first shifting operation.The additional sprocket SP11 includes a plurality of second shifting support sections SP11F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP11F1 is not limited to this embodiment. The total number of the second shifting support sections SP11F2 is not limited to this embodiment.

[0061] In this embodiment, the additional sprocket SP11 includes a plurality of first shifting conveyance recesses SP11R1 to facilitate the first shifting operation. The additional sprocket SP11 includes a plurality of second shifting conveyance recesses SP11R2 to facilitate the second shifting operation. The first shifting conveyance recess SP11R1 is provided in the first shifting conveyance region SP11F1. The second shifting conveyance recess SP11R2 is provided in the second shifting conveyance region SP11F2. However, the first shifting conveyance region SP11F1 may have a different structure instead of or in addition to the first shifting conveyance recess SP11R1. The second shifting conveyance region SP11F2 may have a different structure instead of or in addition to the second shifting conveyance recess SP11R2.

[0062] As in Fig. 18, the additional sprocket SP12 includes a sprocket body SP12A and a plurality of sprocket teeth SP12B. The plurality of sprocket teeth SP12B extend radially outward from the sprocket body SP12A with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. A total number of teeth of the additional sprocket SP12 is equal to or greater than 46. The total number of teeth of the additional sprockets SP12 may also be equal to or greater than 50. The total number of teeth of the additional sprocket SP12 is 51 in this embodiment. However, the total number of the at least one sprocket tooth SP12B of the additional sprocket SP12 is not limited to this embodiment and the above ranges.

[0063] The additional sprocket SP12 includes at least one first shifting assistance region SP12F1 to facilitate a first shifting operation in which the bicycle chain 20 shifts from the additional sprocket SP12 to an adjacent smaller sprocket SP11. The additional sprocket SP12 includes at least one second shifting assistance region SP12F2 to facilitate a second shifting operation in which the bicycle chain 20 shifts from the adjacent smaller sprocket SP11 to the additional sprocket SP12. The adjacent smaller sprocket SP11 is adjacent to the additional sprocket SP12 in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 without another sprocket between the additional sprocket SP12 and the adjacent smaller sprocket SP11. In this embodiment, the additional sprocket SP12 includes a plurality of first shifting assistance regions SP12F1 to facilitate the first shifting operation.The additional sprocket SP12 includes a plurality of second shifting support sections SP12F2 to facilitate the second shifting operation. However, the total number of the first shifting support sections SP12F1 is not limited to this embodiment. The total number of the second shifting support sections SP12F2 is not limited to this embodiment.

[0064] In this embodiment, the additional sprocket SP12 includes a plurality of first shifting conveyance recesses SP12R1 to facilitate the first shifting operation. The additional sprocket SP12 includes a plurality of second shifting conveyance recesses SP12R2 to facilitate the second shifting operation. The first shifting conveyance recess SP12R1 is provided in the first shifting conveyance region SP12F1. The second shifting conveyance recess SP12R2 is provided in the second shifting conveyance region SP12F2. However, the first shifting conveyance region SP12F1 may have a different structure instead of or in addition to the first shifting conveyance recess SP12R1. The second shifting conveyance region SP12F2 may have a different structure instead of or in addition to the second shifting conveyance recess SP12R2.

[0065] As in Fig. As can be seen in Figure 19, the sprockets SP1 to SP12 are separate elements. However, at least one of the sprockets SP1 to SP12 can be provided at least partially integrally with another of the sprockets SP1 to SP12. All of the sprockets SP1 to SP12 can be formed integrally as a unitary unit. In such a case, at least one of the sprockets SP3 to SP12 can have at least ten internal spline or internal spline teeth.

[0066] The rear bicycle sprocket assembly 14 further includes a sprocket support member 37, a plurality of spacers 38, a first ring 39A, and a second ring 39B. The first ring 39A is provided in the axial direction D2 between the second sprocket SP3 and the second sprocket SP4. The second ring 39B is provided in the axial direction D2 between the second sprocket SP4 and the additional sprocket SP5. The additional sprocket is configured to be attached to the sprocket support member 37. In this embodiment, the additional sprockets SP5 to SP12 are configured to be attached to the sprocket support member 37.

[0067] As in Fig. 6, for example, the additional sprocket is fixed to the sprocket support member 37 by an adhesive 37A. In this embodiment, the additional sprockets SP5 to SP12 are attached to the sprocket support member 37 by the adhesive 37A. Thus, it is possible to save weight of the rear bicycle sprocket assembly 14 by reducing or eliminating metal fasteners. However, at least one of the additional sprockets SP5 to SP12 may be attached to the sprocket support member 37 with a structure other than the adhesive 37A (including a metal fastener). At least one of the additional sprockets SP5 to SP12 may be engaged with the sprocket support body 28 without the sprocket support member 37. The sprocket support member 37 may be omitted from the rear bicycle sprocket assembly 14.Furthermore, at least one of the second sprockets SP3 and SP4 can be attached to the sprocket support member 37.

[0068] As in Fig. 4, the locking element 32 includes a tubular body 32A, an externally threaded portion 32B, and a radial projection 32C. The tubular body 32A includes a first axial end 32D and a second axial end 32E. The second axial end 32E is disposed opposite the first axial end 32D in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. As shown in Fig. 6, the first axial end 32D is positioned closer to an axial center plane CPL of the rear bicycle hub assembly 12 than the second axial end 32E in a state in which the rear bicycle sprocket assembly 14 is attached to the rear bicycle hub assembly 12. The axial center plane CPL is perpendicular to the rotational center axis A1. As shown in Fig. 3, the axial center plane CPL is defined to bisect an axial length of the rear bicycle hub assembly 12 in the axial direction D2.

[0069] As in Fig. As seen in Fig. 6, the externally threaded portion 32B is provided at the first axial end 32D to engage with an internally threaded portion 28A of the sprocket support body 28 of the rear bicycle hub assembly 12 in the state in which the rear bicycle sprocket assembly 14 is attached. The radial protrusion 32C extends radially outward from the second axial end 32E with respect to the rotational center axis A1 to restrict axial movement of the first sprocket SP2 relative to the sprocket support body 28 of the rear bicycle hub assembly 12 in the state in which the rear bicycle sprocket assembly 14 is attached to the rear bicycle hub assembly 12.

[0070] The first sprocket SP1 includes a first inward side SP1G and a first outward side SP1H. The first outward side SP1H is opposite to the first inward side SP1G in the axial direction D2. The radial projection 32C is configured to abut against the first sprocket SP1 in the first outward side SP1H. The first sprockets SP1 and SP2 are arranged between the radial projection 32C and the second sprocket SP3 in the axial direction. The first sprockets SP1 and SP2, the second sprocket SP3, the second sprocket SP4, and the first ring 39A are held between the radial projection 32C and the sprocket support member 37 in the axial direction D2.

[0071] As in Fig. As shown in Figure 4, the locking member 32 includes a tool engagement portion 32F. The tool engagement portion 32F is provided on an inner peripheral surface 32A1 of the tubular body 32A to engage with a locking tool (not shown). In this embodiment, the tool engagement portion 32F includes a plurality of engagement grooves 32G that are engaged with the locking tool when the locking member 32 is threadably engaged with the externally threaded portion 32B and the internally threaded portion 28A of the sprocket support body 28.

[0072] As in Fig. 20 and Fig. 21, the sprocket support body 28 has at least one external spline tooth 40 which is adapted to mesh with the rear bicycle sprocket assembly 14 ( Fig. 6). The sprocket support body 28 includes at least ten external spline teeth 40 configured to mesh with the rear bicycle sprocket assembly 14 ( Fig. 6) engage. This means that the at least one external spline tooth 40 comprises a plurality of external spline teeth 40.

[0073] The sprocket support body 28 includes a base support 41 having a tubular shape. The base support 41 extends along the rotational center axis A1. The external spline tooth 40 extends radially outward from the base support 41. The sprocket support body 28 includes a larger diameter portion 42, a flange 44, and a plurality of helical external spline teeth 46. The larger diameter portion 42 and the flange 44 extend radially outward from the base support 41. The larger diameter portion 42 is provided in the axial direction D2 between the plurality of external spline teeth 40 and the flange 44. The larger diameter portion 42 and the flange 44 are provided in the axial direction D2 between the plurality of external spline teeth 40 and the plurality of helical external spline teeth 46. As shown in Fig. As shown in Figure 6, the rear bicycle sprocket assembly 14 is retained in the axial direction D2 between the larger diameter portion 42 and the radial projection 32C of the locking member 32. The larger diameter portion 42 may have an internal cavity so that a drive structure, such as a one-way coupling structure, may be contained within the internal cavity. The larger diameter portion 42 may be omitted from the rear bicycle hub assembly 12 as desired.

[0074] As in Fig. As can be seen in Figure 22, at least one of the at least ten external spline teeth 40 has an axial spline or wedge tooth length SL1. Each of the external spline teeth 40 has the axial spline or wedge tooth length SL1. The axial spline tooth length SL1 is equal to or less than 27 mm. The axial spline tooth length SL1 is equal to or greater than 22 mm. In this embodiment, the axial spline tooth length SL1 is 24.9 mm. However, the axial spline tooth length SL1 is not limited to this embodiment and the above range.

[0075] As in Fig. 23, a total number of the at least ten external spline teeth 40 is equal to or greater than 20. The total number of the at least ten external spline teeth 40 is preferably equal to or greater than 25. The total number of the at least ten external spline teeth 40 is preferably equal to or greater than 28. The total number of external spline teeth 40 is preferably equal to or less than 72. In this embodiment, the total number of external spline teeth 40 is 29. However, the total number of external spline teeth 40 is not limited to this embodiment and the above ranges.

[0076] The at least ten external spline teeth 40 have a first outer pitch angle PA11 and a second outer pitch angle PA12. At least two external spline teeth of the at least ten external spline teeth 40 are arranged circumferentially with respect to the first outer pressure angle PA11 with respect to the rotational center axis A1. In other words, at least two of the plurality of external spline teeth 40 are arranged circumferentially at the first outer pressure angle PA11 with respect to the rotational center axis A1 of the rear bicycle hub assembly 12. At least two external spline teeth of the at least ten external spline teeth 40 are arranged circumferentially at the second outer pitch angle PA12 with respect to the rotational center axis A1 of the rear bicycle hub assembly 12. In other words, at least two of the plurality of external spline teeth 40 are arranged circumferentially at the second outer pitch angle PA12 with respect to the rotational center axis A1 of the rear bicycle hub assembly 12.In this embodiment, the second outer pitch angle PA12 differs from the first outer pitch angle PA11. However, the second outer pitch angle PA12 may be substantially equal to the first outer pitch angle PA11.

[0077] In this embodiment, the external spline teeth 40 are arranged at the first outer pitch angle PA11 in the circumferential direction D1. Two external spline teeth of the external spline teeth 40 are arranged at the second outer pitch angle PA12 in the circumferential direction D1. However, at least two external spline teeth of the external spline teeth 40 may be arranged at a different outer pitch angle in the circumferential direction D1.

[0078] The first outer pitch angle PA11 is in the range of 5 degrees to 36 degrees. The first outer pitch angle PA11 is preferably in the range of 10 degrees to 20 degrees. The first outer pitch angle PA11 is preferably equal to or less than 15 degrees. In this embodiment, the first outer pitch angle PA11 is 12 degrees. However, the first outer pitch angle PA11 is not limited to this embodiment and the above ranges.

[0079] The second outer pitch angle PA12 is in the range of 5 degrees to 36 degrees. In this embodiment, the second outer pitch angle PA12 is 24 degrees. However, the second outer pitch angle PA12 is not limited to this embodiment and the above range.

[0080] At least one of the external spline teeth 40 may have a first spline shape that differs from a second spline shape of another of the external spline teeth 40. At least one of the at least ten external spline teeth 40 may have a first spline size that differs from a second spline size of another of the at least ten external spline teeth 40. At least one of the external spline teeth 40 includes a profile that, when viewed along the rotational center axis A1, differs from a profile of another of the external spline teeth 40. In this embodiment, the external spline tooth 40X includes the first spline shape that differs from the second spline shape of another of the external spline teeth 40.The external spline tooth 40X has a first spline size that is different from the second spline size of another of the external splines 40. As shown in . Fig. However, as can be seen in Figure 24, the at least ten external splines 40 may have the same spline shape. The at least ten external splines 40 may have the same spline size. The at least ten external splines 40 may have the same profile.

[0081] As in Fig. 25, each of the at least ten external spline teeth 40 has an external spline drive surface 48 and an external spline non-drive surface 50. The plurality of external spline teeth 40 includes a plurality of external spline drive surfaces 48 for receiving the drive torque F1 from the rear bicycle sprocket assembly 14 ( Fig. 6) during pedaling. The plurality of external spline teeth 40 include a plurality of external spline non-drive surfaces 50. The external spline drive surface 48 can be brought into contact with the rear sprocket chain assembly 14 to receive the drive torque F1 from the rear bicycle sprocket assembly 14 during pedaling ( Fig. 6). The external spline drive surface 48 faces the reverse rotation direction D12. The external spline drive surface 48 faces an internal spline drive surface 66 of the rear bicycle sprocket assembly 14 in a state where the rear bicycle sprocket assembly 14 is attached to the rear bicycle hub assembly 12. The external spline non-drive surface 50 is provided on a rear side of the external spline drive surface 48 in the circumferential direction D1. The external spline non-drive surface 50 faces the drive rotation direction D11 so as not to receive the drive rotational force F1 from the rear bicycle sprocket assembly 14 during pedaling. The external spline non-drive surface 50 faces an internal spline non-drive surface 68 of the rear bicycle sprocket assembly 14 in a state in which the rear bicycle sprocket assembly 14 is attached to the rear bicycle hub assembly 12.

[0082] The at least ten external spline teeth 40 each comprise a maximum circumferential width MW1. The external spline teeth 40 each comprise a maximum circumferential width MW1. The maximum circumferential width MW1 is defined as a maximum width to accommodate a compressive force F2 applied to the external spline tooth 40. The maximum circumferential width MW1 is defined as a straight line distance based on the external spline drive surface 48.

[0083] The plurality of external spline drive surfaces 48 each have a radially outermost edge 48A and a radially innermost edge 48B. The external spline drive surface 48 extends from the radially outermost edge 48A to the radially innermost edge 48B. A first reference circle RC11 is defined at the radially innermost edge 48B and is centered on the rotational center axis A1. The first reference circle RC11 intersects the external spline non-drive surface 50 at a reference point 50R. The maximum circumferential width MW1 extends straight from the radially innermost edge 48B to the reference point 50R in the circumferential direction D1.

[0084] The plurality of external spline non-drive surfaces 50 each have a radially outermost edge 50A and a radially innermost edge 50B. The external spline non-drive surface 50 extends from the radially outermost edge 50A to the radially innermost edge 50B. In this embodiment, the reference point 50R coincides with the radially innermost edge 50B. However, the reference point 50R may be offset from the radially innermost edge 50B.

[0085] The sum of the maximum circumferential widths MW1 is equal to or greater than 55 mm. The sum of the maximum circumferential widths MW1 is preferably equal to or greater than 60 mm. The sum of the maximum circumferential widths MW1 is preferably equal to or less than 70 mm. In this embodiment, the sum of the maximum circumferential widths MW1 is 60.1 mm. However, the sum of the maximum circumferential widths MW1 is not limited to this embodiment and the above ranges.

[0086] As in Fig. As can be seen in Figure 26, the at least one external spline tooth 40 has an external spline major diameter DM11 that is equal to or less than 34 mm. The external spline major diameter DM11 is equal to or less than 33 mm. The external spline major diameter DM11 is equal to or greater than 29 mm. In this embodiment, the external spline major diameter DM11 is 32.6 mm. However, the external spline major diameter DM11 is not limited to this embodiment and the above ranges.

[0087] The at least one external spline tooth 40 comprises an external spline or external spline minor diameter DM12. The at least one external spline tooth 40 comprises an external spline or external spline root circle RC12 with the external spline minor diameter DM12. However, the external spline root circle RC12 can have a different diameter than the external spline minor diameter DM12. The external spline minor diameter DM12 is equal to or less than 32 mm. The external spline minor diameter DM12 is equal to or less than 31 mm. The external spline minor diameter DM12 is equal to or greater than 28 mm. In this embodiment, the external spline minor diameter DM12 is 30.2 mm. However, the external spline minor diameter DM12 is not limited to this embodiment and the above ranges.

[0088] The larger diameter portion 42 includes an outer diameter DM13 that is larger than the external spline major diameter DM11. The outer diameter DM13 ranges from 32 mm to 40 mm. In this embodiment, the outer diameter DM13 is 35 mm. However, the outer diameter DM13 is not limited to this embodiment.

[0089] As in Fig. 25, the plurality of external spline drive surfaces 48 each include a radial length RL11 defined from the radially outermost edge 48A to the radially innermost edge 48B. A sum of the radial lengths RL11 of the plurality of external spline drive surfaces 48 is equal to or greater than 7 mm. The sum of the radial lengths RL11 is equal to or greater than 10 mm. The sum of the radial lengths RL11 is equal to or greater than 15 mm. The sum of the radial lengths RL11 is equal to or less than 36 mm. In this embodiment, the sum of the radial lengths RL11 is 16.6 mm. However, the sum of the radial lengths RL11 is not limited to this embodiment.

[0090] The plurality of external spline teeth 40 have an additional radial length RL12. The additional radial lengths RL12 are each defined from the outer spline root circle RC12 to the radially outermost ends 40A of the plurality of external spline teeth 40. A sum of the additional radial lengths RL12 is equal to or greater than 20 mm. In this embodiment, the sum of the additional radial lengths RL12 is 31.2 mm. However, the sum of the additional radial lengths RL12 is not limited to this embodiment.

[0091] At least one of the at least ten external splines 40 is circumferentially symmetrical with respect to a reference line CL1. The reference line CL1 extends in a radial direction with respect to the rotational center axis A1 from the rotational center axis A1 to a circumferential center point CP1 of a radially outermost end 40A of the at least one of the at least ten external splines 40. However, at least one of the external splines 40 may have an asymmetric shape with respect to the reference line CL1. The at least one of the at least ten external splines 40 has the external spline drive surface 48 and the external spline non-drive surface 50.

[0092] At least one surface of the plurality of external spline drive surfaces 48 has a first external spline surface angle AG11. The first external spline or external spline surface angle AG11 is defined between the external spline drive surface 48 and a first radial line L11. The first radial line L11 extends from the rotational center axis A1 of the rear bicycle hub assembly 12 to the radially outermost edge 48A of the external spline drive surface 48. The first outer pitch angle PA11 or the second outer pitch angle PA12 is defined between the adjacent first radial lines L11 (see, e.g., Fig. 23) is defined.

[0093] At least one of the external spline non-drive surfaces 50 includes a second external spline surface angle AG12. The second external spline surface angle AG12 is defined between the external spline non-drive surface 50 and a second radial line L12. The second radial line L12 extends from the rotational center axis A1 of the rear bicycle hub assembly 12 to the radially outermost edge 50A of the external spline non-drive surface 50.

[0094] In this embodiment, the second external spline surface angle AG12 is equal to the first external spline surface angle AG11. However, the first external spline surface angle AG11 may be different from the second external spline surface angle AG12.

[0095] The first external spline surface angle AG11 is equal to or less than 6 degrees. The first external spline surface angle AG11 is equal to or greater than 0 degrees. The second external spline surface angle AG12 is equal to or less than 6 degrees. The second external spline surface angle AG12 is equal to or greater than 0 degrees. In this embodiment, the first external spline surface angle AG11 is 5 degrees. The second external spline surface angle AG12 is 5 degrees. However, the first external spline surface angle AG11 and the second external spline surface angle AG12 are not limited to this embodiment and the above ranges.

[0096] As in Fig. 27 and Fig. 28, the brake rotor support body 34 includes at least one additional external spline tooth 52 adapted to be pressed into the bicycle brake rotor 16 ( Fig. 1). In this embodiment, the brake rotor support body 34 includes an additional base support 54 and a plurality of additional external splines 52. The additional base support 54 has a tubular shape and extends from the hub body 36 along the rotational center axis A1. The additional external spline 52 extends radially outward from the additional base support 54. A total number of the additional external spline teeth 52 is 52. However, the total number of the additional external spline teeth 52 is not limited to this embodiment.

[0097] As in Fig. 28, the at least one additional external spline tooth 52 comprises an additional external spline main diameter DM14. As shown in Fig. As can be seen in Figure 29, the additional external spline major diameter DM14 is larger than the external spline major diameter DM11. The additional external spline major diameter DM14 is substantially equal to the outer diameter DM13 of the larger-diameter part 42. However, the additional external spline major diameter DM14 may be equal to or smaller than the external spline major diameter DM11. The additional external spline major diameter DM14 may be different from the outer diameter DM13 of the larger-diameter part 42.

[0098] As in Fig. 29, the hub body 36 includes a first spoke attachment portion 36A and a second spoke attachment portion 36B. A plurality of first spokes SK1 are connected to the first spoke attachment portion 36A. A plurality of second spokes SK2 are connected to the second spoke attachment portion 36B. In this embodiment, the first spoke attachment portion 36A includes a plurality of first attachment holes 36A1. The first spoke SK1 extends through the first attachment hole 36A1. The second spoke attachment portion 36B includes a plurality of second attachment holes 36B1. The second spoke SK2 extends through the second attachment hole 36B1. The term “spoke attachment portion” as used herein includes configurations in which the spoke attachment opening has a flange-like shape such that, as in Fig. 29, the spoke attachment portion extends radially outward with respect to the rotational center axis of the rear bicycle hub assembly, and configurations in which the spoke attachment portion is an opening formed directly on a radially outer peripheral surface of the hub body.

[0099] The second spoke attachment portion 36B is spaced apart from the first spoke attachment portion 36A in the axial direction D2. The first spoke attachment portion 36A is provided between the sprocket support body 28 and the second spoke attachment portion 36B in the axial direction D2. The second spoke attachment portion 36B is provided between the first spoke attachment portion 36A and the brake rotor support body 34 in the axial direction D2.

[0100] The first spoke attachment portion 36A has a first axially outermost part 36C. The second spoke attachment portion 36B has a second axially outermost part 36D. The first axially outermost part 36C includes a surface that faces the first frame BF1 in the axial direction D2 in a state in which the rear bicycle hub assembly 12 is attached to the bicycle frame BF. The second axially outermost part 36D includes a surface that faces the second frame BF2 in the axial direction D2 in a state in which the rear bicycle hub assembly 12 is attached to the bicycle frame BF.

[0101] The hub body 36 includes a first axial length AL1. The first axial length AL1 is defined in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 between the first axially outermost part 36C of the first spoke attachment portion 36A and the second axially outermost part 36D of the second spoke attachment portion 36B. The first axial length AL1 may be equal to or greater than 55 mm. The first axial length AL1 may be equal to or greater than 60 mm. The first axial length AL1 may be equal to or greater than 65 mm. In this embodiment, the first axial length AL1 may be 67 mm. However, the first axial length AL1 is not limited to this embodiment and the above ranges. Examples of the first axial length AL1 include 55.7 mm, 62.3 mm, and 67 mm.

[0102] As in Fig. 29, the hub axle 30 includes a first axial frame abutment surface 30B1 and a second axial frame abutment surface 30C1. The first axial frame abutment surface 30B1 is configured to abut a first portion BF12 of the bicycle frame BF in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14 in a state in which the rear bicycle hub assembly 12 is attached to the bicycle frame BF. The second axial frame abutment surface 30C1 is configured to abut a second portion BF22 of the bicycle frame BF in the axial direction D2 in the state in which the rear bicycle hub assembly 12 is fixed to the bicycle frame BF. The first axial frame abutment surface 30B1 is positioned closer to the sprocket support body 28 in the axial direction D2 than the second axial frame abutment surface 30C1.The sprocket support body 28 is provided in the axial direction D2 between the first axial frame abutment surface 30B1 and the second axial frame abutment surface 30C1.

[0103] The hub axle 30 includes a second axial length AL2 defined in the axial direction D2 between the first axial frame abutment surface 30B1 and the second axial frame abutment surface 30C1. The second axial length AL2 may be equal to or greater than 140 mm. The second axial length AL2 may be equal to or greater than 145 mm. The second axial length AL2 may be equal to or greater than 147 mm. The second axial length AL2 may be 148 mm. However, the second axial length AL2 is not limited to this embodiment and the above ranges. Examples of the second axial length AL2 include 142 mm, 148 mm, and 157 mm.

[0104] A ratio of the first axial length AL1 to the second axial length AL2 may be equal to or greater than 0.3. The ratio of the first axial length AL1 to the second axial length AL2 may be equal to or greater than 0.4. The ratio of the first axial length AL1 to the second axial length AL2 may be equal to or less than 0.5. For example, the ratio of the first axial length AL1 (67 mm) to the second axial length AL2 (148 mm) is approximately 0.45. However, the ratio of the first axial length AL1 to the second axial length AL2 is not limited to this embodiment and the above ranges. Examples of the ratio of the first axial length AL1 to the second axial length AL2 include approximately 0.42 (AL1 is 62.3 mm and AL2 is 148 mm) or approximately 0.39 (AL1 is 55.7 mm and AL2 is 142 mm).

[0105] As in Fig. 6, the sprocket support body 28 includes a first axial end 28B, a second axial end 28C, and an axial sprocket abutment surface 28D. The second axial end 28C is opposite the first axial end 28B in the axial direction D2. The axial center plane CPL bisects the second axial length AL2 in the axial direction D2. The axial sprocket abutment surface 28D is positioned closer to the axial center plane CPL of the rear bicycle hub assembly 12 in the axial direction D2 than the first axial end 28B. The second axial end 28C is positioned closer to the axial center plane CPL of the rear bicycle hub assembly 12 in the axial direction D2 than the axial sprocket abutment surface 28D. The axial sprocket abutment surface 28D is provided on the larger diameter portion 42 in this embodiment, whereas the axial sprocket abutment surface 28D may be provided on other portions of the rear bicycle hub assembly 12 as desired.The axial sprocket abutment surface 28D is in contact with the rear bicycle sprocket assembly 14 in a state where the rear bicycle sprocket assembly 14 is attached to the sprocket bearing body 28. The axial sprocket abutment surface 28D faces the first axial end 28B in the axial direction D2.

[0106] As in Fig. As shown in Figure 6, an axial length AL3 of a sprocket assembly is defined in the axial direction D2 between the first axial frame abutment surface 30B1 and the axial sprocket abutment surface 28D of the sprocket bearing body 28. In this embodiment, the sprocket assembly axial length AL3 is in the range of 35 mm to 45 mm. For example, the axial length AL3 of the sprocket assembly is 39.64 mm. The sprocket assembly axial length AL3 can also be extended to, for example, 44.25 mm by omitting the larger diameter portion 42. However, the sprocket assembly axial length AL3 is not limited to this embodiment and the above range.

[0107] The larger diameter portion 42 has an axial end 42A that is farthest from the first axial frame abutment surface 30B1 in the axial direction D2. An additional axial length AL4 is defined in the axial direction D2 from the first axial frame abutment surface 30B1 to the axial end 42A. The additional axial length AL4 ranges from 38 mm to 47 mm. The additional axial length AL4 may range from 44 mm to 45 mm. The additional axial length AL4 may also range from 40 mm to 41 mm. In this embodiment, the additional axial length AL4 is 44.25 mm. However, the additional axial length AL4 is not limited to this embodiment and the above ranges.

[0108] An axial length AL5 of the larger diameter part 42 is in the range of 3 mm to 6 mm. In this embodiment, the axial length AL5 of the larger diameter part 42 is 4.61 mm. However, the axial length AL5 of the larger diameter part 42 is not limited to this embodiment and the above ranges.

[0109] A ratio of the first axial length AL1 to the sprocket assembly axial length AL3 is in the range of 1.2 to 1.7. For example, the ratio of the first axial length AL1 to the sprocket assembly axial length AL3 is 1.4 when the first axial length AL1 is 55.7 mm and the sprocket assembly axial length AL3 is 39.64 mm. However, the ratio of the first axial length AL1 to the sprocket assembly axial length AL3 is not limited to this embodiment and the above range. For example, the ratio of the first axial length AL1 to the sprocket assembly axial length AL3 may be 1.57 when the first axial length AL1 is 62.3 mm and the sprocket assembly axial length AL3 is 39.64 mm, or the ratio of the first axial length AL1 to the sprocket assembly axial length AL3 may be 1.69 when the first axial length AL1 is 67 mm and the sprocket assembly axial length AL3 is 39.64 mm.

[0110] As in Fig. 30, the sprocket support member 37 includes a hub engaging portion 60 and a plurality of support arms 62. The plurality of support arms 62 extend radially outward from the hub engaging portion 60. The support arm 62 includes first through eighth attachment portions 62A through 62H. The plurality of spacers 38 includes a plurality of first spacers 38A, a plurality of second spacers 38B, a plurality of third spacers 38C, a plurality of fourth spacers 38D, a plurality of fifth spacers 38E, a plurality of sixth spacers 38F, and a plurality of seventh spacers 38G.

[0111] As in Fig. As shown in Figure 6, the first spacers 38A are provided between the additional sprockets SP5 and SP6. The second spacers 38B are provided between the additional sprockets SP6 and SP7. The third spacers 38C are provided between the additional sprockets SP7 and SP8. The fourth spacers 38D are provided between the additional sprockets SP8 and SP9. The fifth spacers 38E are provided between the additional sprockets SP9 and SP10. The sixth spacers 38F are provided between the additional sprockets SP10 and SP11. The seventh spacers 38G are provided between the additional sprockets SP11 and SP12.

[0112] The additional sprocket SP6 and the first spacer 38A are fixed to the first fixing part 62A with the adhesive 37A. The additional sprocket SP7 and the second spacer 38B are fixed to the second fixing part 62B with the adhesive 37A. The additional sprocket SP8 and the third spacer 38C are fixed to the third fixing part 62C with the adhesive 37A. The additional sprocket SP9 and the fourth spacer 38D are fixed to the fourth fixing part 62D with the adhesive 37A. The additional sprocket SP10 and the fifth spacer 38E are fixed to the fifth fixing part 62E with the adhesive 37A. The additional sprocket SP11 and the sixth spacer 38F are fixed to the sixth fixing part 62F with the adhesive 37A. The additional sprocket SP12 and the seventh spacer 38G are fixed to the seventh fixing part 62G with the adhesive 37A.The additional sprocket SP5 and the second ring 39B are fixed to the eighth fixing part 62H with the adhesive 37A. The hub engaging part 60, the sprockets SP1 to SP4, the first ring 39A, and the second ring 39B are held between the larger diameter part 42 and the radial projection 32C of the locking member 32 in the axial direction D2.

[0113] In this embodiment, each of the sprockets SP1 to SP12 is made of a metallic material such as aluminum, iron, or titanium. The sprocket support member 37 is made of a non-metallic material including a resin material. Each of the first to seventh spacers 38A and 38G, the first ring 39A, and the second ring 39B is made of a non-metallic material such as a resin material. However, at least one of the sprockets SP1 to SP12 may be at least partially made of a non-metallic material. At least one of the sprocket support member 37, the first to seventh spacers 38A and 38G, the first ring 39A, and the second ring 39B may be at least partially made of a metallic material such as aluminum, iron, or titanium.

[0114] As in Fig. 7, the first sprocket SP1 includes a first opening SP1K. The first opening SP1K includes a first minimum diameter MD1. As shown in Fig. 31, the tubular body 32A of the locking member 32 extends through the first opening SP1K of the first sprocket SP1 in the state where the rear bicycle sprocket assembly 14 is attached to the sprocket support body 28. The first opening SP1K of the first sprocket SP1 is configured such that the first axial end 32D of the tubular body 32A of the locking member 32 extends through the first opening SP1K of the first sprocket SP1 in the state where the rear bicycle sprocket assembly 14 is fixed to the sprocket support body 28. The first axial end 28B of the sprocket support body 28 is spaced from the first opening SP1K of the first sprocket SP1 without extending through the first opening SP1K. The first minimum diameter MD1 is smaller than a minimum outer diameter MD28 of the sprocket support body 28 of the rear bicycle hub assembly 12.In this embodiment, the minimum outer diameter MD28 is equal to the external spline minor diameter DM12 (. Fig. 26) of the plurality of external spline teeth 40 of the sprocket support body 28.

[0115] As in Fig. As seen in Fig. 31, the tubular body 32A has a first outer diameter ED1 that is equal to or less than 27 mm. The first outer diameter ED1 is equal to or greater than 26 mm. The radial projection 32C has a second outer diameter ED2 that is equal to or less than 32 mm. The second outer diameter ED2 is equal to or greater than 30 mm. In this embodiment, the first outer diameter ED1 is 26.2 mm. The second outer diameter ED2 is 30.8 mm. However, at least one of the first outer diameter ED1 and the second outer diameter ED2 is not limited to this embodiment and the above ranges.

[0116] The radial projection 32C includes an axial width ED3 defined in the axial direction D2. For example, the axial width ED3 of the radial projection 32C is 2 mm. However, the axial width ED3 is not limited to this embodiment.

[0117] The locking element 32 includes an axial length ED4 defined from the radial projection 32C to the first axial end 32D in the axial direction D2. The axial length ED4 of the locking element 32 is 10 mm. However, the axial length ED4 is not limited to this embodiment.

[0118] As in Fig. 8, the first sprocket SP2 has a first opening SP2K. The plurality of first sprockets SP1 and SP2 each include the first opening. The first opening SP2K includes a first minimum diameter MD2. As shown in Fig. As seen in Figure 31, the tubular body 32A of the locking member 32 extends through the first opening SP2K of the first sprocket SP2 in the state in which the rear bicycle sprocket assembly 14 is attached to the sprocket support body 28. The first axial end 28B of the sprocket support body 28 is spaced from the first opening SP2K of the first sprocket SP2 without extending through the first opening SP2K. The first minimum diameter MD2 is smaller than the minimum outer diameter MD28 of the sprocket support body 28 of the rear bicycle hub assembly 12.

[0119] As in Fig. 9, the second sprocket SP3 includes a second opening SP3K. The second opening SP3K includes a second minimum diameter MD3. As shown in Fig. 31, the tubular body 32A of the locking member 32 and the sprocket support body 28 extend through the second opening SP3K of the second sprocket SP3 in the state where the rear bicycle sprocket assembly 14 is attached to the sprocket support body 28. The end 28B of the sprocket support body 28 is provided in the axial direction D2 between the second opening SP3K and the first opening SP1K. The first axial end 28B of the sprocket support body 28 is provided in the axial direction D2 between the second opening SP3K and the first opening SP2K. The second minimum diameter MD3 is equal to or larger than the minimum outer diameter MD28 of the sprocket support body 28 of the rear bicycle hub assembly 12.

[0120] As in Fig. 10, the second sprocket SP4 includes a second opening SP4K. That is, the plurality of second sprockets SP3 and SP4 each include the second opening. The second opening SP4K includes a second minimum diameter MD4. As shown in Fig. As shown in Figure 31, the sprocket support body 28 extends through the second opening SP4K of the second sprocket SP4 in the state where the rear sprocket assembly 14 is attached to the sprocket support body 28. The first axial end 28B of the sprocket support body 28 is provided between the second opening SP4K and the first opening SP1K in the axial direction D2. The second minimum diameter MD4 is equal to or larger than the minimum outer diameter MD28 of the sprocket support body 28 of the rear bicycle hub assembly 12.

[0121] As in Fig. As shown in Figure 32, the first sprocket SP2 includes at least ten internal spline teeth 63 configured to engage the sprocket support body 28 of the rear bicycle hub assembly 12. The at least ten internal spline teeth 63 are provided at the first opening SP2K. The at least ten internal spline teeth 63 are provided as a first torque-transmitting structure of the first sprocket SP2, as described later.

[0122] A total number of the at least ten internal spline teeth 63 of the first sprocket SP2 is equal to or greater than 20. The total number of the at least ten internal spline teeth 63 of the first sprocket SP2 is equal to or greater than 28. The total number of internal spline teeth 63 is equal to or less than 72. In this embodiment, the total number of internal spline teeth 63 is 29. However, the total number of internal spline teeth 63 is not limited to this embodiment and the above ranges.

[0123] As in Fig. As seen in Figure 9, the second sprocket SP3 includes at least ten internal spline teeth 64 configured to engage the sprocket support body 28 of the rear bicycle hub assembly 12. In this embodiment, the at least ten internal spline teeth 64 of the second sprocket SP3 define the second minimum diameter MD3 as an internal spline minor diameter of the at least ten internal spline teeth 64.

[0124] A total number of the at least ten internal spline teeth 64 of the second sprocket SP3 is equal to or greater than 20. The total number of the at least ten internal spline teeth 64 of the second sprocket SP3 is equal to or greater than 29. The total number of internal spline teeth 64 is equal to or less than 72. In this embodiment, the total number of internal spline teeth 64 is 29. However, the total number of internal spline teeth 64 is not limited to this embodiment and the above ranges.

[0125] As in Fig. 10, the second sprocket SP4 includes at least ten internal spline teeth 65 configured to engage the sprocket support body 28 of the rear bicycle hub assembly. Namely, the plurality of second sprockets SP3 and SP4 each comprise the internal toothing(s) of the rear bicycle hub assembly 12. In this embodiment, the at least one of the internal spline teeth 65 of the second sprocket SP4 defines the second minimum diameter MD4 as an internal spline minor diameter of the at least ten internal spline teeth 65.

[0126] A total number of the at least ten internal spline teeth 65 of the second sprocket SP4 is equal to or greater than 20. The total number of the at least ten internal spline teeth 65 of the second sprocket SP4 is equal to or greater than 28. The total number of internal spline teeth 65 is equal to or less than 72. In this embodiment, the total number of internal spline teeth 65 is 29. However, the total number of internal spline teeth 65 is not limited to this embodiment and the above ranges.

[0127] As in Fig. 33, the at least ten internal spline teeth 64 of the second sprocket SP3 have a first inner pitch angle PA21 and a second inner pitch angle PA22. At least two internal spline teeth of the at least ten internal spline teeth 64 of the second sprocket SP3 are circumferentially arranged at the first inner pitch angle PA21 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. The at least two internal spline teeth of the at least ten internal spline teeth 64 are adjacent to each other in the circumferential direction D1 without another spline tooth therebetween. In other words, at least two of the plurality of internal spline teeth 64 are circumferentially arranged about the first inner pitch angle PA21 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14.At least two other internal spline teeth of the at least ten internal spline teeth 64 of the second sprocket SP3 are arranged in the circumferential direction at the second inner pitch angle PA22 with respect to the rotational center axis A1. The at least two other internal spline teeth of the at least ten internal spline teeth 64 of the second sprocket SP3 are adjacent to each other in the circumferential direction D1 without another spline tooth in between. In other words, at least two of the plurality of internal spline teeth 64 of the second sprocket SP3 are arranged in the circumferential direction at the second inner pitch angle PA22 with respect to the rotational center axis A1. In this embodiment, the second inner pitch angle PA22 differs from the first inner pitch angle PA21. However, the second inner pitch angle PA22 may be substantially equal to the first inner pitch angle PA21.

[0128] In this embodiment, the inner spline teeth 64 are arranged circumferentially at the first inner pitch angle PA21 in the circumferential direction D1. Two inner spline teeth of the inner spline teeth 64 are arranged at the second inner pitch angle PA22 in the circumferential direction D1. However, at least two inner spline teeth of the inner spline teeth 64 may be arranged at a different inner pitch angle in the circumferential direction D1.

[0129] The first inner pitch angle PA21 is in the range of 5 degrees to 36 degrees. The first inner pitch angle PA21 is in the range of 10 degrees to 20 degrees. The first inner pitch angle PA21 is equal to or less than 15 degrees. In this embodiment, for example, the first inner pitch angle PA21 is 12 degrees. However, the first inner pitch angle PA21 is not limited to this embodiment and the above ranges.

[0130] The second inner pitch angle PA22 is in the range of 5 degrees to 36 degrees. In this embodiment, the second inner pitch angle PA22 is 24 degrees. However, the second inner pitch angle PA22 is not limited to this embodiment and the above range.

[0131] At least one of the at least ten internal spline teeth 64 of the second sprocket SP3 has a first spline shape that differs from a second spline shape of another of the at least ten internal spline teeth 64. At least one of the at least ten internal spline teeth 64 of the second sprocket SP3 has a first spline size that differs from a second spline size of another of the at least ten internal spline teeth 64. At least one of the at least ten internal spline teeth 64 has a cross-sectional shape that differs from a cross-sectional shape of another of the at least ten internal spline teeth 64. As in Fig. However, as can be seen in Figure 34, the internal spline teeth 64 may have the same shape. The at least ten internal spline teeth 64 may have the same size. The at least ten internal spline teeth 64 may have the same cross-sectional shape.

[0132] As in Fig. 35, at least one of the at least ten internal spline teeth 64 has an internal spline drive surface 66. The at least one of the at least ten internal spline teeth 64 has an internal spline non-drive surface 68. The at least ten internal spline teeth 64 have a plurality of internal spline drive surfaces 66 for transmitting the drive torque F1 from the rear bicycle hub assembly 12 ( Fig. 6). The at least ten internal splines 64 have a plurality of internal spline non-drive surfaces 68. The internal spline drive surface 66 can be brought into contact with the sprocket support body 28 to transmit the driving rotational force F1 from the sprocket SP1 to the sprocket support body 28 during pedaling. The internal spline drive surface 66 faces the driving rotational direction D11. The internal spline drive surface 66 faces the external spline drive surface 48 of the rear bicycle hub assembly 12 in a state in which the rear bicycle chain assembly 14 is attached to the rear bicycle hub assembly 12. The internal spline non-drive surface 68 is provided on a rear side of the internal spline drive surface 66 in the circumferential direction D1.The internal spline non-drive surface 68 is directed in the reverse rotation direction D12 so as not to transmit the driving torque F1 from the sprocket SP1 to the sprocket support body 28 during pedaling. The internal spline non-drive surface 68 faces the external spline non-drive surface 50 of the rear bicycle hub assembly 12 in a state in which the rear bicycle wheel chain assembly 14 is attached to the rear bicycle hub assembly 12.

[0133] The at least ten internal spline teeth 64 each have maximum circumferential widths MW2. The internal spline teeth 64 each have maximum circumferential widths MW2. The maximum circumferential width MW2 is defined as a maximum width to accommodate a compressive force F3 applied to the internal spline tooth 64. The maximum circumferential width MW2 is defined as a straight distance based on the internal spline drive surface 66.

[0134] The plurality of internal spline drive surfaces 66 each include a radially outermost edge 66A and a radially innermost edge 66B. A second reference circle RC21 is defined at the radially outermost edge 66A and is centered on the rotational center axis A1. The second reference circle RC21 intersects the internal spline non-drive surface 68 at a reference point 68R. The maximum circumferential width MW2 extends straight from the radially innermost edge 66B to the reference point 68R in the circumferential direction D1.

[0135] The internal spline non-drive surface 68 has a radially outermost edge 68A and a radially innermost edge 68B. The internal spline non-drive surface 68 extends from the radially outermost edge 68A to the radially innermost edge 68B. The reference point 68R is provided between the radially outermost edge 68A and the radially innermost edge 68B.

[0136] The sum of the maximum circumferential widths MW2 is equal to or greater than 40 mm. The sum of the maximum circumferential widths MW2 can be equal to or greater than 45 mm. The sum of the maximum circumferential widths MW2 can be equal to or greater than 50 mm. In this embodiment, the sum of the maximum circumferential widths MW2 is 50.8 mm. However, the sum of the maximum circumferential widths MW2 is not limited to this embodiment.

[0137] As in Fig. 36, the at least ten internal spline teeth 64 of the second sprocket SP3 have an internal spline major diameter DM21. The at least one internal spline tooth 64 of the second sprocket SP3 includes an internal spline root circle RC22 with the internal spline major diameter DM21. The internal spline major diameter DM21 is equal to or less than 34 mm. The internal spline major diameter DM21 of the second sprocket SP3 is equal to or less than 33 mm. The internal spline major diameter DM21 of the second sprocket SP3 is equal to or greater than 29 mm. In this embodiment, the internal spline major diameter DM21 of the second sprocket SP3 is 32.8 mm. However, the internal spline major diameter DM21 of the second sprocket SP3 is not limited to this embodiment and the above ranges.

[0138] The at least ten internal spline teeth 64 of the second sprocket SP3 have an internal spline minor diameter DM22 that is equal to or less than 32 mm. The internal spline minor diameter DM22 is equal to or less than 31 mm. The internal spline minor diameter DM22 is equal to or greater than 28 mm. In this embodiment, the internal spline minor diameter DM22 is 30.4 mm. However, the internal spline minor diameter DM22 is not limited to this embodiment and the above ranges.

[0139] As in Fig. As can be seen in Figure 18, the additional sprocket SP12 includes a largest tooth tip diameter TD12. The largest tooth tip diameter TD12 is a maximum outer diameter defined by the plurality of sprocket teeth SP12B. A ratio of the internal spline major diameter DM21 ( Fig. 36) to the largest tooth tip diameter TD12 is in the range of 0.15 to 0.18. In this embodiment, the ratio of the internal spline major diameter DM21 to the largest tooth tip diameter TD12 is 0.15. However, the ratio of the internal spline major diameter DM21 to the largest tooth tip diameter TD12 is not limited to this embodiment and the above ranges.

[0140] As in Fig. 35, the plurality of internal spline drive surfaces 66 include the radially outermost edge 66A and the radially innermost edge 66B. The plurality of internal spline drive surfaces 66 each have a radial length RL21 defined from the radially outermost edge 66A to the radially innermost edge 66B. A sum of the radial lengths RL21 of the plurality of internal spline drive surfaces 66 is equal to or greater than 7 mm. The sum of the radial lengths RL21 is equal to or greater than 10 mm. The sum of the radial lengths RL21 is equal to or greater than 15 mm. The sum of the radial lengths RL21 is equal to or less than 36 mm. In this embodiment, the sum of the radial lengths RL21 is 16.6 mm. However, the sum of the radial lengths RL21 is not limited to this embodiment and the above ranges.

[0141] The plurality of internal splines 64 have an additional radial length RL22. The additional radial lengths RL22 are each defined from the internal spline root circle RC22 to the radially innermost ends 64A of the plurality of internal splines 64. A sum of the additional radial lengths RL22 is equal to or greater than 12 mm. In this embodiment, the sum of the additional radial lengths RL22 is 34.8 mm. However, the sum of the additional radial lengths RL22 is not limited to this embodiment and the above ranges.

[0142] At least one of the at least ten internal spline teeth 64 of the second sprocket SP3 is circumferentially symmetrical with respect to a reference line CL2. The reference line CL2 extends from the rotational center axis A1 to a circumferential center point CP2 of a radially innermost end 64A of the at least one of the at least ten internal spline teeth 64 in a radial direction with respect to the rotational center axis A1. However, at least one of the internal spline teeth 64 may have an asymmetric shape with respect to the reference line CL2. The at least one of the internal spline teeth 64 includes the internal spline drive surface 66 and the internal spline non-drive surface 68.

[0143] The internal spline drive surface 66 has a first internal spline surface angle AG21. The first internal spline surface angle AG21 is defined between the internal spline drive surface 66 and a first radial line L21. The first radial line L21 extends from the rotational center axis A1 of the rear bicycle sprocket assembly 14 to the radially outermost edge 66A of the internal spline drive surface 66. The first inner pitch angle PA21 or the second inner pitch angle PA22 is defined between the adjacent first radial lines L21 (see, for example, Fig. 33) is defined.

[0144] The internal spline non-drive surface 68 has a second internal spline surface angle AG22. The second internal spline surface angle AG22 is defined between the internal spline non-drive surface 68 and a second radial line L22. The second radial line L22 extends from the rotational center axis A1 of the rear bicycle sprocket assembly 14 to the radially outermost edge 68A of the internal spline non-drive surface 68.

[0145] In this embodiment, the second internal spline face angle AG22 is equal to the first internal spline face angle AG21. However, the first internal spline face angle AG21 may differ from the second internal spline face angle AG22.

[0146] The first internal spline face angle AG21 is in the range of 0 degrees to 6 degrees. The second internal spline face angle AG22 is in the range of 0 degrees to 6 degrees. In this embodiment, the first internal spline face angle AG21 is 5 degrees. The second internal spline face angle AG22 is 5 degrees. However, the first internal spline face angle AG21 and the second internal spline face angle AG22 are not limited to this embodiment and the above ranges.

[0147] As in Fig. As seen in Fig. 37, the internal spline teeth 64 mesh with the external spline teeth 40 to transmit the driving rotational force F1 from the second sprocket SP3 to the sprocket support body 28. The internal spline drive surface 66 can be brought into contact with the internal spline drive surface 48 to transmit the driving rotational force F1 from the second sprocket SP3 to the sprocket support body 28. The internal spline non-drive surface 68 is spaced from the external spline non-drive surface 50 in a state where the internal spline drive surface 66 is in contact with the external spline drive surface 48.

[0148] The internal spline teeth 63 of the first sprocket SP2 and the internal spline teeth 65 of the second sprocket SP4 comprise substantially the same structure as the internal spline teeth 64 of the second sprocket SP3. Therefore, they will not be described in detail here for the sake of brevity.

[0149] As in Fig. 2, the sprocket support member 37 includes at least ten internal spline teeth 76 configured to engage the sprocket support body 28 of the rear bicycle hub assembly 12. The plurality of internal spline teeth 76 have substantially the same structure as the plurality of internal spline teeth 64. Therefore, for the sake of brevity, they will not be described in detail here.

[0150] As in Fig. 38, the first sprocket SP1 includes a first torque transmission structure SP1T provided on the first inward side SP1H for directly or indirectly transmitting a pedaling torque to the sprocket support body 28. In this embodiment, the first torque transmission structure SP1T includes a plurality of first torque transmission teeth SP1T1 for indirectly transmitting a pedaling torque to the sprocket support body 28. The first torque transmission structure SP1T includes at least ten first torque transmission teeth SP1T1. Preferably, a total number of the at least ten first torque transmission teeth SP1T1 is equal to or greater than 20. More preferably, a total number of the at least ten first torque transmission teeth SP1T1 is equal to or greater than 28. In this embodiment, the total number of the at least ten first torque transmission teeth SP1T1 is 29.However, the total number of at least ten first torque transmission teeth SP1T1 is not limited to this embodiment and the above ranges.

[0151] As in Fig. 38 and Fig. 39, the first sprocket SP2 includes a first inboard side SP2H and a first outboard side SP2G. The first outboard side SP2G is disposed opposite the first inboard side SP2H in the axial direction D2 with respect to the rotational center axis A1 of the rear bicycle sprocket assembly 14. The first sprocket SP2 includes a first torque transmitting structure SP2M provided on the first inboard side SP2H for directly or indirectly transmitting pedal torque to the sprocket support body 28. In this embodiment, the inner spline tooth 63 of the first sprocket SP2 may also be referred to as a first torque transmitting tooth 63. The first torque transmitting structure SP2M includes the plurality of first torque transmitting teeth 63 for directly transmitting pedal torque to the sprocket support body 28.The first torque transmission structure SP2M includes at least ten first torque transmission teeth 63. The total number of the at least ten first torque transmission teeth 63 is equal to or greater than 20. More preferably, the total number of the at least ten first torque transmission teeth 63 is equal to or greater than 28. In this embodiment, the total number of the at least ten first torque transmission teeth 63 is 29. However, the total number of the at least ten first torque transmission teeth 63 is not limited to this embodiment and the above ranges. The first torque transmission tooth 63 may also be referred to as the internal spline tooth 63.

[0152] As in Fig. 39, the first sprocket SP2 includes a second torque transmission structure SP2T for receiving pedal torque from the first sprocket SP1. The second torque transmission structure SP2T is provided on the first outward side SP2G. In this embodiment, the second torque transmission structure SP2T includes a plurality of second torque transmission teeth SP2T1. Preferably, a total number of the second torque transmission teeth SP2T1 is equal to or greater than 20. More preferably, the total number of the second torque transmission teeth SP2T1 is equal to or greater than 28. In this embodiment, the total number of the second torque transmission teeth SP2T1 is 29. However, the total number of the second torque transmission teeth SP2T1 is not limited to this embodiment and the above ranges. The first torque transmission structure SP1T is engaged with the second torque transmission structure SP2T.The plurality of first torque transmission teeth SP1T1 mesh with the plurality of second torque transmission teeth SP2T1 to transmit the driving torque F1.

[0153] As in Fig. 23 and Fig. As seen in Fig. 24, the sprocket support body 28 includes a hub indicator 28I provided at one axial end of the base bracket 41. The hub indicator 28I is provided in a range of the second outer lead angle PA12 when viewed along the rotational center axis A1. In this embodiment, the hub indicator 28I includes a dot. However, the hub indicator 28I may also include other shapes, such as a triangle and a line. Further, the hub indicator 28I may be a separate member attached to the sprocket support body 28, for example, with a bonding structure such as an adhesive. The position of the hub indicator 28I is not limited to this embodiment.

[0154] As in Fig. As seen in Fig. 7, the first sprocket SP1 includes a sprocket indicator SP1I provided at one axial end of the sprocket body SP1A. In this embodiment, the sprocket indicator SP1I includes a dot. However, the sprocket indicator SP1I may also include other shapes, such as a triangle and a line. Further, the sprocket indicator SP1I may be a separate member attached to the sprocket SP1, for example, with a bonding structure such as an adhesive. The position of the sprocket indicator SP1I is not limited to this embodiment. The sprocket indicator SP1I may be provided on any of the other sprockets SP2 to SP12. The sprocket indicator SP1I may also be provided on the sprocket support member 37.

[0155] As in Fig. 6, the rear bicycle hub assembly 12 further includes a freewheel structure 78. The sprocket support body 28 is operatively connected to the hub body 36 with the freewheel structure 78. The freewheel structure 78 is configured to connect the sprocket support body 28 to the hub body 36 in order to rotate the sprocket support body 28 together with the hub body 36 in the drive rotation direction D11 ( Fig. 5). The freewheel structure 78 is configured to allow the sprocket support body 28 to rotate relative to the hub body 36 in the reverse rotation direction D12 ( Fig. 5). Accordingly, the freewheel structure 78 can be described as a one-way clutch structure 78. The freewheel structure 78 will be described in detail later.

[0156] The rear bicycle hub assembly 12 includes a first bearing 79A and a second bearing 79B. The first bearing 79A and the second bearing 79B are provided between the sprocket support body 28 and the hub axle 30 to rotatably support the sprocket support body 28 with respect to the hub axle 30 about the rotational center axis A1.

[0157] In this embodiment, the sprocket support body 28, the brake rotor support body 34, and the hub body 36 are all made of a metallic material, such as aluminum, iron, or titanium. However, at least one of the sprocket support body 28, the brake rotor support body 34, and the hub body 36 may be made of a non-metallic material.

[0158] As in Fig. 40, the freewheel structure 78 includes a first ratchet element 80 and a second ratchet element 82. The first ratchet element 80 is configured to engage one of the hub body 36 and the sprocket support body 28 in a torque-transmitting manner. The second ratchet element 82 is configured to engage the other of the hub body 36 and the sprocket support body 28 in a torque-transmitting manner. In this embodiment, the first pawl element 80 engages the sprocket support body 28 in a torque-transmitting manner. The second pawl element 82 engages the hub body 36 in a torque-transmitting manner. However, the first pawl member 80 may be configured to engage the hub body 36 in a torque-transmitting manner.The second pawl member 82 may be configured to engage the sprocket support body 28 in a torque-transmitting manner.

[0159] The first pawl member 80 is attached to the sprocket support body 28 to rotate together with the sprocket support body 28 relative to the hub body 36 about the rotational center axis A1. The second pawl member 82 is attached to the hub body 36 to rotate together with the hub body 36 relative to the sprocket support body 28 about the rotational center axis A1. Each of the first pawl member 80 and the second pawl member 82 has an annular shape.

[0160] At least one of the first pawl member 80 and the second pawl member 82 is movable relative to the hub axle 30 in the axial direction D2 with respect to the rotational center axis A1. In this embodiment, both the first pawl member 80 and the second pawl member 82 are movable relative to the hub axle 30 in the axial direction D2. The second pawl member 82 is movable relative to the hub body 36 in the axial direction D2. The first pawl member 80 is movable relative to the sprocket support body 28 in the axial direction D2.

[0161] The hub body 36 includes a freewheel housing 36H having an annular shape. The freewheel housing 36H extends in the axial direction D2. The first pawl element 80 and the second pawl element 82 are provided in a fixed state in the freewheel housing 36H.

[0162] As in Fig. 41, the first pawl element 80 includes at least one first ratchet tooth 80A. In this embodiment, the at least one first pawl tooth 80A includes a plurality of first pawl teeth 80A. The plurality of first pawl teeth 80A are arranged in the circumferential direction D1 to provide a spline engagement.

[0163] As in Fig. 42, the second pawl element 82 comprises at least one second ratchet tooth 82A configured to engage with the at least one first pawl tooth 80A in a torque-transmitting manner. The at least one second pawl tooth 82A engages with the at least one first pawl tooth 80A to transmit the rotational force F1 from the sprocket support body 28 to the hub body 36 ( Fig. 40). In this embodiment, the at least one second ratchet tooth 82A comprises a plurality of second ratchet teeth 82A configured to engage with the plurality of first ratchet teeth 80A in a torque-transmitting manner. The plurality of second ratchet teeth 82A are arranged in the circumferential direction D1 to provide spline engagement. The plurality of second ratchet teeth 82A can be engaged with the plurality of first ratchet teeth 80A. The first pawl member 80 and the second pawl member 82 rotate together in a state where the second ratchet teeth 82A are engaged with the first ratchet teeth 80A.

[0164] As in Fig. 41 and Fig. 42, the sprocket support body 28 includes an outer peripheral surface 28P with a first helical spline 28H. The first pawl member 80 is configured to engage the sprocket support body 28 in a torque-transmitting manner and includes a second helical spline 80H that mates with the first helical spline 28H. The first pawl member 80 is movably mounted in the axial direction D2 with respect to the sprocket support body 28 via the second helical spline 80H that mates with the first helical spline 28H during drive by a first thrust force applied by the sprocket support body 28. In this embodiment, the first helical spline 28H includes the plurality of helical external splines 46.The second helical spline 80H includes a plurality of helical internal spline teeth 80H1 that mate with the plurality of helical external spline teeth 46.

[0165] As in Fig. 43, the hub body 36 includes an inner circumferential surface 36S and at least one first tooth 36T. The at least one first tooth 36T is provided on the inner circumferential surface 36S. In this embodiment, the freewheel housing 36H includes the inner circumferential surface 36S. The hub body 36 includes a plurality of first teeth 36T. The plurality of first teeth 36T are provided on the inner circumferential surface 36S and extend radially inward from the inner circumferential surface 36S with respect to the rotational center axis A1. The first teeth 36T are arranged in the circumferential direction D1 to define a plurality of recesses 36R between adjacent two teeth of the first teeth 36T.

[0166] The second pawl member 82 includes a hub body engagement portion 82E that engages the hub body 36 in a torque-transmitting manner to transmit the rotational force F1 from the first pawl member 80 to the hub body 36 via the hub body engagement portion 82E. One of the hub body engagement portion 82E and the hub body 36 includes at least one protrusion that extends radially. The other of the hub body engagement portion 82E and the hub body 36 includes at least one recess that engages the at least one protrusion. In this embodiment, the hub body engagement portion 82E includes at least one protrusion 82T that extends radially as at least one protrusion. The hub body 36 includes at least one recess 36R that engages the at least one protrusion 82T. In this embodiment, the hub body engaging portion 82E includes a plurality of projections 82T.The plurality of projections 82T engage with the plurality of recesses 36R.

[0167] As in Fig. 42, the outer peripheral surface 28P of the sprocket support body 28 has a guide portion 28G configured to guide the first pawl element 80 toward the hub body 36 during coasting. The guide portion 28G is arranged to form an obtuse angle AG28 ( Fig. 48) with the first helical spline 28H. The sprocket support body 28 includes a plurality of guide portions 28G. The guide portion 28G is configured to guide the first pawl element 80 toward the hub body 36 during coasting or freewheeling. The guide portion 28G guides the first pawl element 80 toward the hub body 36 to provide meshing engagement between the at least one first pawl tooth 80A ( Fig. 41) and the at least one second pawl tooth 82A. The guide portion 28G is configured to move the first pawl element 80 away from the second pawl element 82 in the axial direction D2. The guide portion 28G extends at least in the circumferential direction D1 with respect to the sprocket support body 28. The guide portion 28G extends from one tooth of the plurality of helical external spline teeth 46 in at least the circumferential direction D1. While the guide portion 28G is provided integrally with the helical external spline tooth 46 as a one-piece unitary member in this embodiment, the guide portion 28G may be a separate member from the plurality of helical external spline teeth 46.The first pawl element 80 and the second pawl element 82 are smoothly disengaged from each other during coasting due to the guide portion 28G, particularly in a case where the guide portion 28G is arranged to define an obtuse angle AG 28 with respect to the first spiral gear 28H. This also results in a reduction in noise during coasting because the at least one first pawl tooth 80A and the at least one second pawl tooth 82A are smoothly disengaged from each other during coasting.

[0168] As in Fig. 40, the rear bicycle hub assembly 12 further includes a biasing member 84. The biasing member 84 is disposed between the hub body 36 and the first pawl member 80 to bias the first pawl member 80 in the axial direction D2 toward the second pawl member 82. In this embodiment, the biasing member 84 is, for example, a compression spring.

[0169] As in Fig. 44, the biasing member 84 is compressed in the axial direction D2 between the hub body 36 and the first pawl member 80. The biasing member 84 biases the first pawl member 80 toward the second pawl member 82 to maintain an engaged state in which the first pawl member 80 and the second pawl member 82 are engaged with each other via the first pawl teeth 80A and the second pawl teeth 82A.

[0170] Preferably, the biasing member 84 is engaged with the hub body 36 to rotate with the hub body 36. The biasing member 84 is attached to the hub body 36 to rotate together with the hub body 36 about the rotational center axis A1 ( Fig. 40). The biasing element 84 comprises a wound body 84A and a connecting end 84B. The hub body 36 has a connecting hole 36F. The connecting end 84B is provided in the connecting hole 36F, so that the biasing element 84 rotates together with the hub body 36 about the rotational center axis A1 ( Fig. 40) turns around.

[0171] As in Fig. 44, the outer peripheral surface 28P of the sprocket support body 28 supports the first pawl member 80 and the second pawl member 82. The first pawl member 80 includes an axially directed surface 80S directed toward the axial direction D2. The at least one first pawl tooth 80A is disposed on the axially directed surface 80S of the first pawl member 80. In this embodiment, the plurality of first pawl teeth 80A are disposed on the axially directed surface 80S of the first pawl member 80. The axially directed surface 80S is substantially perpendicular to the axial direction D2. However, the axially directed surface 80S may not be perpendicular to the axial direction D2.

[0172] The second pawl member 82 includes an axially directed surface 82S directed in the axial direction D2. The at least one second pawl tooth 82A is disposed on the axially directed surface 82S of the second pawl member 82. The axially directed surface 82S of the second pawl member 82 faces the axially directed surface 80S of the first pawl member 80. In this embodiment, the plurality of second pawl teeth 82A are disposed on the axially directed surface 82S of the second pawl member 82. The axially directed surface 82S is substantially perpendicular to the axial direction D2. However, the axially directed surface 82S may not be perpendicular to the axial direction D2.

[0173] As in Fig. 40, the rear bicycle hub assembly 12 includes a spacer 86, a support member 88, a sliding member 90, an additional biasing member 92, and a receiving member 94. However, it is possible to omit at least one of the spacer member 86, the support member 88, the sliding member 90, the additional biasing member 92, and the receiving member 94 from the rear bicycle hub assembly 12.

[0174] As in Fig. 44 and Fig. 45, the spacer 86 is at least partially provided between the at least one first tooth 36T and the at least one projection 82T in the circumferential direction D1 defined around the rotational center axis A1. In this embodiment, the spacer 86 is partially provided between the first teeth 36T and the projections 82T in the circumferential direction D1. However, the spacer 86 may be entirely provided between the first teeth 36T and the projections 82T in the circumferential direction D1.

[0175] As in Fig. 45 to 47, the spacer 86 includes at least one intermediate portion 86A provided between the at least one first tooth 36T and the at least one projection 82T. The at least one intermediate portion 86A is provided between the at least one first tooth 36T and the at least one projection 82T in the circumferential direction D1. In this embodiment, the spacer 86 includes a plurality of intermediate portions 86A, each provided between the first teeth 36T and the projections 82T in the circumferential direction D1. While the spacer 86 includes the intermediate portions 86A in this embodiment, the spacer 86 may include one intermediate portion 86A.

[0176] As in Fig. 46 and Fig. As shown in Figure 47, the spacer 86 includes a connecting portion 86B. The plurality of intermediate portions 86A extend from the connecting portion 86B in the axial direction D2 parallel to the rotational center axis A1. While the spacer 86 includes the connecting portion 86B in this embodiment, the connecting portion 86B may be omitted from the spacer 86.

[0177] The spacer 86 comprises a non-metallic material. In this embodiment, the non-metallic material comprises a resin material. Examples of the resin material include synthetic resin. The non-metallic material may comprise a material other than the resin material instead of or in addition to the resin material. While in this embodiment, the intermediate portions 86A and the connecting portion 86B are provided integrally with each other as a one-piece unitary member, at least one of the intermediate portions 86A may be a separate portion from the connecting portion 86B.

[0178] As in Fig. 44 and Fig. 45, the plurality of intermediate portions 86A are provided between the inner peripheral surface 36S of the hub body 36 and an outer peripheral surface 82P of the second pawl member 82 in the radial direction.

[0179] As in Fig. 44, the support member 88 is provided in the axial direction D2 between the hub body 36 and the second pawl member 82. The support member 88 is attached to the second pawl member 82. The support member 88 is provided radially outward from the first pawl member 80. The support member 88 can be brought into contact with the first pawl member 80. The support member 88 preferably comprises a non-metallic material. The support member 88, which is made of a non-metallic material, reduces noise during operation of the rear bicycle hub assembly 12. In this embodiment, the non-metallic material comprises a resin material. The non-metallic material may comprise another material instead of the resin material or in addition to the resin material.

[0180] The sliding member 90 is provided in the axial direction D2 parallel to the rotational center axis A1 between the sprocket support body 28 and the second pawl member 82. The second pawl member 82 is provided in the axial direction D2 between the first pawl member 80 and the sliding member 90. The sliding member 90 is preferably a non-metallic material. The sliding member 90, which is made of a non-metallic material, reduces noise during operation of the rear bicycle hub assembly 12. In this embodiment, the non-metallic material comprises a resin material. The non-metallic material may comprise a material other than the resin material instead of or in addition to the resin material.

[0181] The sprocket support body 28 includes a stop 28E for abutting the second pawl element 82 to limit axial movement of the second pawl element 82 away from the hub body 36. In this embodiment, the stop 28E can abut the second pawl element 82 via the sliding element 90. Alternatively, the stop 28E can directly abut the second pawl element 82. The first pawl element 80 is arranged on an axial side of the second pawl element 82 that is opposite the stop 28E of the sprocket support body 28 in the axial direction D2. The sliding element 90 is provided in the axial direction D2 between the stop 28E of the sprocket support body 28 and the second pawl element 82.

[0182] As in Fig. 44, the additional biasing member 92 is provided in the axial direction D2 between the hub body 36 and the second pawl member 82 to bias the second pawl member 82 toward the sprocket support body 28. In this embodiment, the additional biasing member 92 biases the second pawl member 82 in the axial direction D2 via the carrier member 88. The additional biasing member 92 is provided radially outward of the biasing member 84. The additional biasing member 92 is provided radially outward of the plurality of second pawl teeth 82A in this embodiment.

[0183] The receiving member 94 comprises a non-metallic material. The receiving member 94, made of a non-metallic material, prevents the biasing member 84 from being over-preloaded during operation of the rear hub assembly 12. In this embodiment, the non-metallic material comprises a resin material. The non-metallic material may comprise a material other than the resin material instead of the resin material. The receiving member 94 includes an axially receiving portion 96 and a radially receiving portion 98. The axially receiving portion 96 is provided in the axial direction D2 between the first pawl member 80 and the biasing member 84. The radially receiving portion 98 extends from the axially receiving portion 96 in the axial direction D2. The radially receiving portion 98 is provided radially inward of the biasing member 84.The axial receiving portion 96 and the radial receiving portion 98 are provided integrally as a one-piece unitary element. However, the axial receiving portion 96 may be a separate element from the radial receiving portion 98.

[0184] As in Fig. 44, the rear hub assembly 12 includes a sealing structure 100. The sealing structure 100 is provided between the sprocket support body 28 and the hub body 36. The hub body 36 has an interior space 102. Each of the sprocket support body 28, the biasing member 84, the first pawl member 80, and the second pawl member 82 are at least partially disposed within the interior space 102 of the hub body 36. The interior space 102 is sealed by the sealing structure 100. In this embodiment, no lubricant is provided within the interior space 102. However, the rear hub assembly 12 may include a lubricant provided within the interior space 102. Any gap between the elements disposed within the interior space 102 may be reduced when no lubricant is provided, compared to a case where the rear hub assembly 12 may include a lubricant provided within the interior space 102.

[0185] The operation of the rear bicycle hub assembly is described in the Fig. 44, Fig. 48 and Fig. 49 described.

[0186] As in Fig. 44, the axial direction D2 includes a first axial direction D21 and, opposite to the first axial direction D21, a second axial direction D22. A biasing force F5 is exerted by the biasing element 84 on the receiving element 94 in the first axial direction D21. The biasing force F5 of the biasing element 84 biases the receiving element 94, the first pawl element 80, the second pawl element 82, and the sliding element 90 toward the sprocket support body 28 in the first axial direction D21. This engages the first spline teeth 80A with the second pawl teeth 82A.

[0187] As in Fig. 48, when a pedal torque T1 is input to the sprocket support body 28 in the drive rotation direction D11, the helical spline teeth 80H1 are guided by the helical spline teeth 46 with respect to the sprocket support body 28 in the first axial direction D21. This strongly engages the first spline teeth 80A with the second ratchet teeth 82A. In this state, the pedal torque T1 is transmitted from the sprocket support body 28 to the hub body 36 ( Fig. 44) via the first latch element 80 and the second latch element 82 ( Fig. 44).

[0188] As in Fig. 48, the first pawl element 80 is in contact with the guide portion 28G to roll out of the second pawl element 82 with a rotational friction force F6 acting between the biasing element 84 ( Fig. 44) and the first pawl element 80. As shown in Fig. 49, a freewheel torque T2 is applied to the hub body 36 in the direction of rotation D11 during coasting. The freewheel torque T2 is transmitted by the hub body 36 ( Fig. 44) via the second latch element 82 ( Fig. 44) is transmitted to the first pawl member 80. At this time, the helical inner spline teeth 80H1 are guided by the helical outer spline teeth 46 relative to the sprocket support body 28 in the second axial direction D22. This moves the first pawl member 80 relative to the sprocket support body 28 in the second axial direction D22 against the biasing force F5. Thus, the first pawl member 80 is moved away from the second pawl member 82 in the second axial direction D22, thereby weakening the engagement between the first pawl teeth 80A and the second pawl teeth 82A. This allows rotation of the second pawl member 82 relative to the first pawl member 80 in the drive rotation direction D11, thereby preventing the idle torque T2 from being transmitted from the hub body 36 via the first pawl member 80 and the second pawl member 82 to the sprocket support body 28.At this time, the first ratchet teeth 80A slide with the second ratchet teeth 82A in the circumferential direction D1. Modifications

[0189] As in Fig. 50, in the above embodiments and other modifications, the external spline 40 may include a groove 40G provided in the circumferential direction D1 between the external spline drive surface 48 and the external spline non-drive surface 50. The groove 40G reduces the weight of the rear bicycle hub assembly 12.

[0190] As in Fig. As seen in Fig. 51, in the above and other modifications, the internal spline 64 may have a groove 64G provided between the internal spline drive surface 66 and the internal spline non-drive surface 68 in the circumferential direction D1. The groove 64G reduces the weight of the rear bicycle sprocket assembly 14.

[0191] In the present application, at least ten internal spline teeth may be provided indirectly at a second opening of a second sprocket, while the at least ten internal spline teeth are provided directly at the second opening of each of the second sprockets SP3 and SP4 in the above embodiments. For example, instead of providing at least ten internal spline teeth directly at the second opening of the second sprocket SP3 and / or the second sprocket SP4, at least one of the second sprockets SP3 and SP4 may be attached to a sprocket support member having at least ten internal spline teeth. Alternatively, instead of providing at least ten internal spline teeth at a second opening of a second sprocket, at least one second sprocket may be integrally molded with at least one additional sprocket having at least ten internal spline teeth as a one-piece unitary member.Since such a second sprocket indirectly has at least ten internal spline teeth via a sprocket support member and / or an additional sprocket, this also means that the second sprocket has at least ten internal spline teeth configured to engage with a sprocket support body of a bicycle hub unit.

[0192] The rear bicycle sprocket assembly 14 may include only one first sprocket or more than two first sprockets, while in the above embodiments the rear bicycle sprocket assembly 14 includes two first sprockets SP1 and SP2.

[0193] The rear bicycle sprocket assembly 14 may include only one second sprocket or more than two second sprockets, whereas in the above embodiments, the rear bicycle sprocket assembly 14 includes two second sprockets SP3 and SP4.

[0194] As in Fig. 52, in the sprocket support body 28, the total number of at least ten external spline teeth 40 can be in the range of 22 to 24. For example, the total number of at least ten external spline teeth 40 can be 23. The first outer pitch angle PA11 can be in the range of 13 degrees to 17 degrees. For example, the first outer pitch angle PA11 can be 15 degrees. The second outer pitch angle PA12 can be in the range of 28 degrees to 32 degrees. For example, the second outer pitch angle PA12 can be 30 degrees. The first outer pitch angle PA11 is half of the second outer pitch angle PA12. However, the first outer pitch angle PA11 can be different from half of the second outer pitch angle PA12. The total number of at least ten external spline teeth 40 is not limited to the above modifications and ranges.The first outer pitch angle PA11 is not limited to the above modifications and ranges. The second outer pitch angle PA12 is not limited to the above modifications and ranges.

[0195] As in Fig. 53, in the sprocket support body 28, the sum of the radial lengths RL11 of the plurality of external spline drive surfaces 48 can range from 11 mm to 14 mm. The sum of the radial lengths RL11 of the plurality of external spline drive surfaces 48 can be 12.5 mm. The sum of the additional radial lengths RL12 can be between 26 mm and 30 mm. For example, the sum of the additional radial lengths RL12 can be 28.2 mm. However, the sum of the additional radial lengths RL12 is not limited to the above modifications and ranges.

[0196] As in Fig. 54, in the first torque transmission structure SP1T of the first sprocket SP1, the total number of the at least ten first torque transmission teeth SP1T1 may be in the range of 22 to 24. For example, the total number of the at least ten first torque transmission teeth SP1T1 may be 23. However, the total number of the at least ten first torque transmission teeth SP1T1 is not limited to the above modification and range.

[0197] As in Fig.As can be seen in FIG. 55, in the second torque transmission structure SP2T of the first sprocket SP2, the total number of the at least ten second torque transmission teeth SP2T1 may be in the range of 22 to 24. The total number of the at least ten second torque transmission teeth SP2T1 may be, for example, 23. However, the total number of the at least ten second torque transmission teeth SP2T1 is not limited to the above modification and range.

[0198] As in Fig. 56, in the first sprocket SP2, the total number of at least ten internal spline teeth 63 of the first sprocket SP2 may be in the range of 22 to 24. For example, the total number of at least ten internal spline teeth 63 of the first sprocket SP2 may be 23. However, the total number of at least ten internal spline teeth 63 is not limited to the above modification and range.

[0199] As in Fig. 57, in the second sprocket SP3, the total number of at least ten internal spline teeth 64 of the second sprocket SP3 may be in the range of 22 to 24. The total number of at least ten internal spline teeth 64 of the second sprocket SP3 may be, for example, 23. However, the total number of at least ten internal spline teeth 64 is not limited to the above modification and range.

[0200] As in Fig. 58, in the second sprocket SP4, the total number of at least ten internal spline teeth 65 of the second sprocket SP4 may be in the range of 22 to 24. The total number of at least ten internal spline teeth 65 of the second sprocket SP4 may be, for example, 23. However, the total number of at least ten internal spline teeth 65 is not limited to the above modification and range.

[0201] As in Fig. 59, in the at least ten internal spline teeth 64 of the second sprocket SP3, the first inner lead angle PA21 may be in the range of 13 degrees to 17 degrees. The first inner lead angle PA21 may be, for example, 15 degrees. The second inner lead angle PA22 may be between 28 degrees and 32 degrees. The second inner lead angle PA22 may be, for example, 30 degrees. The first inner lead angle PA21 may be half of the second inner lead angle PA22. However, the first inner lead angle PA21 may deviate from half of the second inner lead angle PA22. The first inner lead angle PA21 is not limited to the above modification and range. The second inner lead angle PA22 is not limited to the above modification and range.

[0202] As in Fig. 60, in the internal spline teeth 64 of the second sprocket SP3, the sum of the radial lengths RL21 of the plurality of internal spline drive surfaces 66 can range from 11 mm to 14 mm. The sum of the radial lengths RL21 of the plurality of internal spline drive surfaces 66 can be, for example, 12.5 mm. However, the sum of the radial lengths RL21 is not limited to the above modification and range. The sum of the additional radial lengths RL22 can range from 26 mm to 29 mm. The sum of the additional radial lengths RL22 is, for example, 27.6 mm. However, the sum of the additional radial lengths RL22 is not limited to this embodiment and the above ranges. The internal spline teeth 63 of the first sprocket SP2 and the internal spline teeth 65 of the second sprocket SP4 comprise the same structures as the internal spline teeth 64 of the second sprocket SP3.

[0203] As in Fig. 61, the internal spline teeth 76 of the sprocket support member 37 may have the same structures as the internal spline teeth 64 of the second sprocket SP3 shown in the Fig. 57, Fig. 59 and Fig. 60. The total number of at least ten internal spline teeth 76 of the sprocket support member 37 may be in the range of 22 to 24. The total number of at least ten internal spline teeth 76 of the sprocket support member 37 may be, for example, 23. However, the total number of at least ten internal spline teeth 76 is not limited to the above modification and range. The structure of the internal spline teeth 64 shown in Fig. 60 can be applied to the internal spline teeth 76 of the sprocket support member 37.

[0204] As in Fig. 62, the rear bicycle sprocket assembly 14 may include an additional sprocket SP13. The additional sprocket SP13 is connected to the additional sprocket SP12 with a plurality of coupling elements SP13R. The additional sprocket SP13 includes a sprocket body SP13A and at least one sprocket tooth SP13B. The sprocket body SP13A of the additional sprocket SP13 is connected to the sprocket body SP12A of the additional sprocket SP12 with the plurality of coupling elements SP13R. The at least one sprocket tooth SP13B extends radially outward from the sprocket body SP13A. A total number of at least one sprocket tooth SP13B is greater than the total number of the at least one sprocket tooth SP12B. Preferably, the total number of teeth of the at least one sprocket tooth SP13B is equal to or greater than 46. More preferably, the total number of teeth of the at least one sprocket tooth SP13B is equal to or greater than 50.For example, the total number of teeth of at least one sprocket tooth SP13B is 54.

[0205] The tooth profile of the sprocket teeth SP1B to SP13B of the sprockets SP1 to SP13 can have a conventional tooth profile and / or a narrow / wide tooth profile. In particular, the sprocket teeth SP1B to SP13B of the sprockets SP1 to SP13 can also have, as a narrow / wide tooth profile, at least one first tooth, each with a first axial maximum chain engagement width, and at least one second tooth, each with a second axial maximum chain engagement width that is smaller than the first axial maximum chain engagement width. The first axial maximum chain engagement width and the second axial maximum chain engagement width are measured along the axial direction D2.The first axial maximum chain engagement width is larger than an axial inner connection space defined by a pair of inner connection plates of the bicycle chain 20 and smaller than an axial outer connection space defined by a pair of outer connection plates of the bicycle chain 20, the pair of outer connection plates facing each other in the axial direction D2 when the bicycle chain 20 is engaged with one of the sprockets SP1B to SP13B. The second axial maximum chain engagement width is smaller than the axial inner connection space defined by the pair of inner connection plates of the bicycle chain 20.Accordingly, the at least one first tooth is configured to engage with a pair of outer link plates of the bicycle chain 20, wherein the pair of outer link plates face each other in the axial direction D2 when the bicycle chain 20 is engaged with one of the sprockets SP1B to SP13B, and the at least one second tooth is configured to engage with a pair of inner link plates of the bicycle chain 20, wherein the pair of inner link plates face each other in the axial direction D2. Preferably, the at least one first tooth and the at least one second tooth are arranged alternately on an outer circumference of at least one of the sprockets SP1B to SP13B.Preferably, the sprocket teeth SP1B to SP13B of the sprockets SP1 to SP13 include a plurality of first teeth each having the above-mentioned first maximum chain engagement width and a plurality of second teeth each having the above-mentioned second maximum chain engagement width. Preferably, the plurality of first teeth and the plurality of second teeth are alternately arranged on an outer periphery of at least one of the sprockets SP1B to SP13B. Preferably, sprocket teeth of a largest sprocket may have such a narrow / wide tooth profile. Accordingly, it is preferable that the sprocket teeth SP12B of the sprocket SP12 in . Fig. 6 or the sprocket teeth SP13B of the sprocket SP13 in Fig. 62 have at least one first tooth with the above-mentioned first axially maximum chain engagement width and at least one second tooth with the above-mentioned second axially maximum chain engagement width.

[0206] The term "comprising" and its derivatives, as used herein, are to be understood as open-ended terms that specify the presence of the stated features, elements, components, groups, integers, and / or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers, and / or steps. This concept also applies to words with similar meanings, such as the terms "having," "including," and their derivatives.

[0207] The terms “member”, “section”, “portion”, “part”, “element”, “body” and “structure”, when used in the singular, can have the dual meaning of a single part or of multiple parts.

[0208] The ordinal numbers such as "first" and "second" as used in the present application are merely identifiers and have no other meaning, such as a specific order or the like. Furthermore, for example, the term "first element" itself does not imply the existence of a "second element," and the term "second element" itself does not imply the existence of a "first element."

[0209] The term “pair of” as used herein may include the configuration in which the pair of elements have different shapes or structures from each other in addition to the configuration in which the pair of elements have the same shapes or structures.

[0210] The terms “a” (or “an”), “one or more” and “at least one” may be used interchangeably herein.

[0211] Finally, the extent terms such as "substantially," "by," and "approximately," as used herein, mean a reasonable amount of variation from the modified term such that the final result is not significantly altered. All numerical values ​​described in this application can be interpreted to include "substantially," "by," and "approximately."

[0212] Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

[1] A rear bicycle sprocket assembly (14) adapted to be attached to a sprocket support body (28) of a rear bicycle hub assembly (12), the rear bicycle sprocket assembly (14) comprising: several bicycle sprockets, including: a first sprocket (SP1; SP2), comprising: a first opening (SP1K; SP2K) having a first minimum diameter (MD1; MD2) that is smaller than a minimum outer diameter (MD28) of the sprocket support body (28) of the rear bicycle hub assembly (12); and a second sprocket (SP3; SP4), comprising: a second opening (SP3K; SP4K) having a second minimum diameter (MD3; MD4) equal to or greater than the minimum outer diameter (MD28) of the sprocket support body (28) of the rear bicycle hub assembly (12); and at least ten internal spline teeth (63; 64; 65) adapted to engage the sprocket support body (28) of the rear bicycle hub assembly (12), the first sprocket (SP1; SP2) comprising: a first inward-facing side (SP1H; SP2H); and a first outwardly directed side opposite the first inwardly directed side (SP1H; SP2H) in an axial direction with respect to a rotational center axis (A1) of the rear bicycle sprocket assembly (14); and the first sprocket (SP1; SP2) has a first torque transmission structure (SP1T) provided on the first inward-facing side (SP1H; SP2H) for transmitting a pedal actuation torque directly or indirectly to the sprocket support body (28). [2] A rear bicycle sprocket assembly (14) according to claim 1, wherein the total number of said at least ten internal spline teeth (63; 64; 65) of said second sprocket (SP3; SP4) is in the range of 22 to 24. [3] A rear bicycle sprocket assembly (14) according to claim 1 or 2, further comprising a locking element (32) comprising: a tubular body extending through the first opening (SP1K; SP2K) of the first sprocket (SP1; SP2) in a state in which the rear bicycle sprocket assembly (14) is attached to the rear bicycle hub assembly (12), the tubular body (32A) comprising: a first axial end (32D); and a second axial end (32E) opposite the first axial end (32D) in an axial direction with respect to a rotational center axis of the rear bicycle sprocket assembly (14), wherein, in the state in which the rear bicycle sprocket assembly (14) is attached to the rear bicycle hub assembly (12), the first axial end (32D) is positioned closer to an axial center plane of the rear bicycle hub assembly (12) than the second axial end (32E); an externally threaded portion (32B) provided at the first axial end (32D) for engaging with an internally threaded portion (28A) of the sprocket support body (28) of the rear bicycle hub assembly (12) in the state in which the rear bicycle sprocket assembly (14) is attached to the rear bicycle hub assembly (12); and a radial projection (32C) extending radially outward from the second axial end (32E) with respect to the rotational center axis for restricting axial movement of the first sprocket (SP1; SP2) with respect to the sprocket support body (28) of the rear bicycle hub assembly (12) in the state in which the rear bicycle sprocket assembly (14) is attached to the rear bicycle hub assembly (12). [4] The bicycle rear sprocket assembly (14) according to claim 3, wherein the locking member (32) has a tool engagement portion (32F). [5] A rear bicycle sprocket assembly (14) according to claim 3 or 4, wherein the radial projection (32C) is configured to abut / come into contact with the first sprocket (SP1; SP2) on the first outwardly directed side. [6] The bicycle rear sprocket assembly (14) of claim 5, wherein the tubular body (32A) has a first outer diameter (ED1) equal to or less than 27 mm. [7] Rear bicycle sprocket assembly (14) according to claim 6, wherein the first outer diameter (ED1) is equal to or less than 26 mm [8] A bicycle rear sprocket assembly (14) according to any one of claims 3 to 7, wherein the radial projection (32C) comprises a second outer diameter (ED2) equal to or less than 32 mm. [9] Rear bicycle sprocket assembly (14) according to claim 8, wherein the second outer diameter (ED2) is equal to or greater than 30 mm [10] The rear bicycle sprocket assembly (14) according to any one of claims 1 to 9, wherein the second sprocket (SP3; SP4) is arranged adjacent to the first sprocket (SP1; SP2) in an axial direction with respect to a rotational center axis (A1) of the rear bicycle sprocket assembly (14) without another sprocket between the first sprocket (SP1; SP2) and the second sprocket (SP3; SP4). [11] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 10, wherein the first torque transmitting structure (SP1T) comprises at least ten first torque transmitting teeth (SP1T1). [12] A rear bicycle sprocket assembly (14) according to claim 11, wherein a total number of said at least ten first torque transmitting teeth (SP1T1) is equal to or greater than 20 [13] The rear bicycle sprocket assembly (14) of claim 11, wherein a total number of said at least ten first teeth ranges from 22 to 24. [14] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 13, wherein a total number of said at least ten internal spline teeth (63; 64; 65) of said second sprocket (SP3; SP4) is equal to or greater than 20. [15] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 14, wherein the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) have a first inner pitch angle (PA21) and a second inner pitch angle (PA22) different from the first inner pitch angle (PA21). [16] A rear sprocket assembly according to any one of claims 1 to 15, wherein at least one of the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) has a first spline shape that is different from a second spline shape of another of the at least ten internal spline teeth (63; 64; 65). [17] A rear sprocket assembly according to any one of claims 1 to 16, wherein at least one of the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) has a first spline size that is different from a second spline size of another of the at least ten internal spline teeth (63; 64; 65). [18] Rear sprocket assembly according to one of claims 1 to 17, wherein a total number of teeth of the first sprocket (SP1; SP2) is equal to or less than 10 and / or the first sprocket (SP1; SP2) is the smallest sprocket in the rear sprocket assembly of the bicycle. [19] Rear bicycle sprocket assembly (14) according to one of claims 1 to 18, further comprising a sprocket support element (37) having at least ten internal spline teeth (63; 64; 65) adapted to engage the sprocket support body (28) of the rear bicycle hub assembly (12), wherein the plurality of bicycle sprockets comprise an additional sprocket (SP5, SP6, SP7, SP8, SP9, SP10, SP11, SP12, SP13) adapted to be attached to the sprocket support member (37). [20] A rear bicycle sprocket assembly (14) according to claim 19, wherein the additional sprocket (SP5, SP6, SP7, SP8, SP9, SP10, SP11, SP12, SP13) is / is fixed to the sprocket support member (37) by adhesive. [21] A rear bicycle sprocket assembly (14) according to claim 19 or 20, wherein the sprocket support member (37) is made of a non-metallic material comprising a resin material [22] Rear bicycle sprocket assembly (14) according to one of claims 1 to 21, wherein the plurality of bicycle sprockets comprise a plurality of second sprockets provided as the second sprocket (SP3; SP4), and the plurality of second sprockets each comprise at least ten internal spline teeth (63; 64; 65) configured to engage the sprocket support body (28) of the rear bicycle hub assembly (12). [23] Rear bicycle sprocket assembly (14) according to claim 22, further comprising a sprocket support member (37) having at least ten internal spline teeth (63; 64; 65) adapted to engage the sprocket support body (28) of the rear bicycle hub assembly (12), wherein the plurality of bicycle sprockets comprise an additional sprocket (SP5, SP6, SP7, SP8, SP9, SP10, SP11, SP12, SP13) which is adapted to be / be attached to the sprocket support member (37). [24] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 23, wherein the plurality of bicycle sprockets comprise: a plurality of first sprockets provided as the first sprocket (SP1; SP2), the plurality of first sprockets each comprising the first opening (SP1K; SP2K); and a plurality of second sprockets provided as the second sprocket (SP3; SP4), the plurality of second sprockets each having the second opening (SP3K; SP4K) and the at least ten internal spline teeth (63; 64; 65) configured to engage the sprocket support body (28) of the rear bicycle hub assembly (12). [25] Rear bicycle sprocket assembly (14) according to one of claims 1 to 24, wherein at least two internal spline teeth of the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) are arranged circumferentially at a first inner pitch angle (PA21) with respect to a rotational center axis (A1) of the rear bicycle sprocket assembly (14), and the first inner pitch angle (PA21) is in the range of 5 degrees to 36 degrees. [26] A rear bicycle sprocket assembly (14) according to claim 25, wherein the first inner pitch angle (PA21) is in the range of 10 degrees to 20 degrees. [27] A rear bicycle sprocket assembly (14) according to claim 25, wherein the first inner pitch angle (PA21) is equal to or less than 15 degrees. [28] Rear bicycle sprocket assembly (14) according to one of claims 25 to 27, wherein at least two other internal spline teeth of the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) are arranged circumferentially at a second inner pitch angle (PA22) with respect to the rotational center axis (A1), and the second inner pitch angle (PA22) differs from the first inner pitch angle (PA21). [29] A rear bicycle sprocket assembly (14) according to claim 28, wherein the first inner pitch angle (PA21) is half of the second inner pitch angle (PA22). [30] A rear bicycle sprocket assembly (14) according to claim 28 or 29, wherein the second inner pitch angle (PA22) is in the range of 28 degrees to 32 degrees. [31] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 30, wherein the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) have an internal spline major diameter equal to or less than 34 mm. [32] A rear bicycle sprocket assembly (14) according to claim 31, wherein the internal spline major diameter of the second sprocket (SP3; SP4) is equal to or greater than 29 mm. [33] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 32, wherein the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) have an internal spline minor diameter (DM22) equal to or less than 32 mm. [34] A rear bicycle sprocket assembly (14) according to claim 33, wherein the internal spline minor diameter (DM22) is equal to or greater than 28 mm. [35] Rear bicycle sprocket assembly (14) according to one of claims 1 to 34, wherein the at least ten internal spline teeth (63; 64; 65) have a plurality of internal spline drive surfaces (66) for receiving a driving torque from the rear bicycle hub assembly (12) during pedaling, the plurality of internal spline drive surfaces (66) each comprise a radially outermost edge (66A), a radially innermost edge (66B), and a radial length (RL21) defined from the radially outermost edge (66A) to the radially innermost edge (66B), and a sum of the radial lengths (RL21) of the plurality of internal spline drive surfaces (66) is equal to or greater than 7 mm. [36] The rear bicycle sprocket assembly (14) of claim 35, wherein the sum of the radial lengths (RL21) of the plurality of internal spline drive surfaces (66) is equal to or greater than 10 mm. [37] A rear bicycle sprocket assembly (14) according to claim 35 or 36, wherein the sum of the radial lengths (RL21) of the plurality of internal spline drive surfaces (66) is equal to or greater than 15 mm [38] A rear bicycle sprocket assembly (14) according to any one of claims 35 to 37, wherein the sum of the radial lengths (RL21) is equal to or less than 36 mm. [39] Rear bicycle sprocket assembly (14) according to one of claims 1 to 38, wherein at least one of the at least ten internal spline teeth (63; 64; 65) comprises an internal spline drive surface (66) having a first internal spline surface angle (AG21) defined between the internal spline drive surface (66) and a first radial line (L11) extending from a rotational center axis (A1) of the rear bicycle sprocket assembly (14) to a radially outermost edge (66A) of the internal spline drive surface (66), and the first internal spline face angle (AG21) is in the range of 0 degrees to 6 degrees. [40] Rear bicycle sprocket assembly (14) according to claim 39, wherein which comprises at least one of the at least ten internal spline teeth (63; 64; 65) an internal spline non-drive surface (68) having a second internal spline surface angle (AG22) defined between the internal spline non-drive surface (68) and a second radial line (L21) extending from the rotational center axis (A1) of the rear bicycle sprocket assembly (14) to a radially outermost edge (68A) of the internal spline non-drive surface (68), and the second internal spline face angle (AG22) is in the range of 0 degrees to 6 degrees. [41] A rear bicycle sprocket assembly (14) according to any one of claims 1 to 40, wherein at least one of the at least ten internal spline teeth (63; 64; 65) of the second sprocket (SP3; SP4) is circumferentially symmetrical with respect to a reference line (CL1) extending from the rotational center axis (A1) to a circumferential center point (CP1) of a radially outermost end (40A) of the at least one of the at least ten internal spline teeth (63; 64; 65) in a radial direction with respect to the rotational center axis (A1).

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