Bicycle sprocket assembly and bicycle sprocket

Abstract

A bicycle sprocket assembly includes a first sprocket and a second sprocket. The first sprocket includes a plurality of first sprocket teeth, a first sprocket inward-facing surface, a first sprocket outward-facing surface, and an axial space. The second sprocket includes a plurality of second sprocket teeth, a second sprocket inward-facing surface, and a second sprocket outward-facing surface. When one of the plurality of second sprocket teeth is axially engaged between an axially inward inner link plate and an axially outward inner link plate, and when the second sprocket outward-facing surface contacts the axially outward inner link plate, an axial space is defined as the space between the first sprocket outward-facing surface and the axially outward inner link plate in the axial direction. The axial space is greater than 0 mm and equal to or less than 0.15 mm.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of August 19, 2021, application number 2021109550420, and invention name “Bicycle Sprocket Assembly and Bicycle Sprocket”. Technical Field

[0002] The present invention relates to a bicycle sprocket assembly and a bicycle sprocket. Background Art

[0003] Human-powered vehicles include a sprocket assembly configured to engage with a chain. Such sprocket assemblies are known, for example, from U.S. Patent Nos. 4,889,521 and 6,340,338. Based on this prior art, the present invention provides a bicycle sprocket assembly with smooth shifting performance. Another object of the present invention is to provide a bicycle sprocket with high rigidity. The bicycle sprocket assembly and bicycle sprocket according to the present invention can be used in an electric-assisted bicycle in which not only human torque but also motor torque is applied to the bicycle sprocket. Summary of the Invention

[0004] According to a first aspect of the present invention, a bicycle sprocket assembly includes a first sprocket and a second sprocket. The first sprocket includes a first sprocket body, a plurality of first sprocket teeth, a first sprocket inward-facing surface, and a first sprocket outward-facing surface. The plurality of first sprocket teeth are disposed on the outer periphery of the first sprocket body. The plurality of first sprocket teeth define a first maximum tooth tip diameter. The first sprocket inward-facing surface is configured to face the axial center plane of the bicycle when the bicycle sprocket assembly is mounted on the bicycle. The first sprocket outward-facing surface is disposed on the opposite side of the first sprocket inward-facing surface in the axial direction relative to the rotational axis of the bicycle sprocket. The second sprocket is axially adjacent to the first sprocket with no other sprocket therebetween. The second sprocket includes a second sprocket body, a plurality of second sprocket teeth, a second sprocket inward-facing surface, and a second sprocket outward-facing surface. The plurality of second sprocket teeth are disposed on the outer periphery of the second sprocket body. The plurality of second sprocket teeth define a second maximum tooth tip diameter that is smaller than the first maximum tooth tip diameter. The second sprocket inward-facing surface is configured to face the axial center plane of the bicycle when the bicycle sprocket assembly is mounted on the bicycle. The second sprocket outward-facing surface is disposed axially opposite the second sprocket inward-facing surface. The first sprocket includes an upshift facilitating section and an axial space. The upshift facilitating section is configured to facilitate an upshift operation of the bicycle chain from the first sprocket to the second sprocket. When one of the plurality of second sprocket teeth is axially positioned between an axially inward inner plate and an axially outward inner plate of a pair of opposing inner link plates, and the second sprocket outward-facing surface of the one of the plurality of second sprocket teeth contacts the axially outward inner plate of the pair of opposing inner link plates, an axial space is defined axially between the first sprocket outward-facing surface of the one of the plurality of first sprocket teeth and the axially outward inner plates of the pair of opposing outer link plates. In an assembled state of the bicycle chain, the axially inward inner plate and the axially outward outer plate of the pair of opposing outer link plates are axially spaced apart from each other. In an assembled state of the bicycle chain, the axially inward inner plate and the axially outward inner plate of the pair of opposing inner link plates are axially spaced apart from each other. The axial space is greater than 0 mm and equal to or less than 0.15 mm.

[0005] With the bicycle sprocket assembly according to the first aspect, if the axial clearance is equal to or less than 0 mm, a downshift operation, in which the bicycle sprocket shifts from the second sprocket to the first sprocket, may occur unintentionally. This unintentional downshift operation may cause a greater shock. If the axial clearance is greater than 0.15 mm, the downshift operation is likely to fail unexpectedly. Therefore, compared to a first sprocket with an axial clearance of equal to or less than 0 mm or greater than 0.15 mm, if a cyclist performs a downshift operation, the shock during the downshift operation can be reduced while ensuring the downshift operation.

[0006] In accordance with a second aspect of the present invention, the bicycle sprocket assembly according to the first aspect is configured so that the first sprocket includes a downshift facilitating section configured to facilitate a downshift operation of shifting the bicycle chain from the second sprocket toward the first sprocket.

[0007] With the bicycle sprocket assembly in accordance with the second aspect, compared to a first sprocket without the downshift facilitating section, it is possible to effectively reduce shock during a downshift operation while reducing unintentional downshift operations.

[0008] According to a third aspect of the present invention, a bicycle sprocket includes a sprocket body, an inner sprocket side, an outer sprocket side, and a plurality of sprocket teeth. The inner sprocket side is configured to be closer to the axial center plane of the bicycle than the outer sprocket side when the bicycle sprocket is mounted on the bicycle. The outer sprocket side is located on the opposite side of the inner sprocket side in the axial direction relative to the rotational axis of the bicycle sprocket. The plurality of sprocket teeth are disposed on the outer circumference of the sprocket body. The plurality of sprocket teeth include at least one recessed tooth having at least one recessed portion recessed from the outer sprocket side toward the inner sprocket side. The at least one recessed portion has a circumferential upstream end and a circumferential downstream end opposite the circumferential upstream end in the circumferential direction relative to the rotational axis and relative to the driving rotational direction. The circumferential upstream end has a first axial thickness defined on the pitch circle of the bicycle sprocket. The circumferential downstream end has a second axial thickness defined on the pitch circle of the bicycle sprocket. The second axial thickness is less than the first axial thickness. The first axial thickness is equal to or greater than 1.3 mm. The third aspect can be combined with the first or second aspect.

[0009] With the bicycle sprocket according to the third aspect, the at least one recessed tooth suppresses an increase in the weight of the bicycle sprocket because the at least one recessed tooth has a second axial thickness that is smaller than the first axial thickness. Furthermore, the first axial thickness is equal to or greater than 1.3 mm, ensuring the strength of the at least one recessed tooth compared to bicycle sprockets having a first axial thickness of less than 1.3 mm. Therefore, the strength of the at least one recessed tooth can be ensured while suppressing an increase in the weight of the bicycle sprocket.

[0010] In accordance with a fourth aspect of the present invention, the bicycle sprocket according to the third aspect of the present invention is configured so that each of the plurality of sprocket teeth is configured to enter each of an outer chain space defined between a pair of opposing outer link plates of the bicycle chain and an inner chain space defined between a pair of opposing inner link plates of the bicycle chain.

[0011] With the bicycle sprocket in accordance with the fourth aspect, the total number of the plurality of sprocket teeth can be an odd number.

[0012] In accordance with a fifth aspect of the present invention, the bicycle sprocket according to the third or fourth aspect is configured so that the at least one recessed portion has an inclined surface extending between a circumferential upstream end and a circumferential downstream end.

[0013] With the bicycle sprocket according to the fifth aspect, the inclined surface can make the downshift operation smoother, reduce noise during the downshift operation and / or reduce wear of the bicycle sprocket.

[0014] In accordance with a sixth aspect of the present invention, the bicycle sprocket according to the third or fourth aspect is configured so that the at least one recessed portion has at least one step surface provided between a circumferential upstream end portion and a circumferential downstream end portion.

[0015] With the bicycle sprocket according to the sixth aspect, the dimensional accuracy of the at least one concave portion can be improved, thereby improving the manufacturing efficiency of the bicycle sprocket.

[0016] In accordance with a seventh aspect of the present invention, the bicycle sprocket according to the sixth aspect is configured so that at least one step surface of at least one recess forms at least three steps.

[0017] With the bicycle sprocket according to the seventh aspect, the dimensional accuracy of the at least one concave portion can be improved, thereby improving the manufacturing efficiency of the bicycle sprocket.

[0018] According to an eighth aspect of the present invention, the bicycle sprocket according to any one of the third to seventh aspects further includes an upshift facilitating section and a downshift facilitating section. The upshift facilitating section is configured to facilitate an upshift operation of shifting the bicycle chain from the bicycle sprocket toward a smaller sprocket that is adjacent to the bicycle sprocket in an axial direction without another sprocket therebetween. The downshift facilitating section is configured to facilitate a downshift operation of shifting the bicycle chain from the smaller sprocket toward the bicycle sprocket. The downshift facilitating section is disposed upstream of the upshift facilitating section in a circumferential direction.

[0019] With the bicycle sprocket according to the eighth aspect, the width of some sprocket teeth among the plurality of sprocket teeth can be increased, thereby improving the strength of the bicycle sprocket.

[0020] According to a ninth aspect of the present invention, the bicycle sprocket according to the eighth aspect is configured so that the upshift facilitation section is formed by a first tooth group among the plurality of sprocket teeth, and the downshift facilitation section is formed by a second tooth group among the plurality of sprocket teeth. The second tooth group is completely different from the first tooth group.

[0021] With the bicycle sprocket according to the ninth aspect, the thickness of some sprocket teeth among the plurality of sprocket teeth can be increased, thereby improving the strength of the bicycle sprocket.

[0022] According to a tenth aspect of the present invention, a bicycle sprocket includes a sprocket body, a plurality of sprocket teeth, an upshift facilitating section, and a downshift facilitating section. The plurality of sprocket teeth are disposed on an outer circumferential edge of the sprocket body. The upshift facilitating section is configured to facilitate an upshift operation of the bicycle chain from a bicycle sprocket to a smaller sprocket, the smaller sprocket being adjacent to the bicycle sprocket in an axial direction relative to the rotational axis of the bicycle sprocket with no other sprocket therebetween. The upshift facilitating section is formed by a first set of teeth among the plurality of sprocket teeth. The downshift facilitating section is configured to facilitate a downshift operation of the bicycle chain from the smaller sprocket to the bicycle sprocket. The downshift facilitating section is formed by a second set of teeth among the plurality of sprocket teeth. The second set of teeth is completely different from the first set of teeth. The downshift facilitating section is disposed upstream of the upshift facilitating section in a circumferential direction relative to the rotational axis of the bicycle sprocket and in a driving rotational direction. At least one sprocket tooth among the plurality of sprocket teeth has an axial tooth root thickness equal to or greater than 1.7 mm. The tenth aspect can be combined with any one of the first to ninth aspects.

[0023] With the bicycle sprocket according to the tenth aspect, it is possible to improve the durability of the bicycle sprocket while reducing shock in at least one of an upshift operation and a downshift operation.

[0024] In accordance with an eleventh aspect of the present invention, the bicycle sprocket according to the tenth aspect is configured so that the first tooth set of the upshift promotion section is adjacent to the second tooth set of the downshift promotion section without another tooth therebetween.

[0025] With the bicycle sprocket in accordance with the eleventh aspect, it is possible to further improve the durability of the bicycle sprocket while reducing shock in at least one of an upshift operation and a downshift operation.

[0026] In accordance with a twelfth aspect of the present invention, the bicycle sprocket according to the tenth or eleventh aspect of the present invention is configured so that each of the plurality of sprocket teeth is configured to enter each of an outer chain space defined between a pair of opposing outer link plates of the bicycle chain and an inner chain space defined between a pair of opposing inner link plates of the bicycle chain.

[0027] With the bicycle sprocket in accordance with the twelfth aspect, the total number of the plurality of sprocket teeth can be an odd number.

[0028] According to a thirteenth aspect of the present invention, a bicycle sprocket includes a sprocket body, an inner sprocket side, an outer sprocket side, and a plurality of sprocket teeth. The inner sprocket side is configured to be closer to the axial center plane of the bicycle than the outer sprocket side when the bicycle sprocket is mounted on the bicycle. The outer sprocket side is located on the opposite side of the inner sprocket side in the axial direction relative to the rotational axis of the bicycle sprocket. The plurality of sprocket teeth are disposed on the outer peripheral edge of the sprocket body. At least one of the plurality of sprocket teeth has a tooth tip, a tooth root, and at least one tooth tip chamfer formed on the tooth tip on at least one of the outer sprocket side and the inner sprocket side. The at least one tooth tip chamfer has a radially outermost end and a radially innermost end relative to the rotational axis of the bicycle sprocket. A radial tooth tip distance from the tooth root to the tooth tip in the radial direction relative to the rotational axis is defined as being equal to or greater than 4.5 mm. A radial chamfer distance from the tooth root to the radially innermost end of the at least one tooth tip chamfer is defined as being equal to or greater than 3 mm. The thirteenth aspect can be combined with any one of the first to twelfth aspects.

[0029] With the bicycle sprocket according to the thirteenth aspect, the radial addendum distance and the radial chamfer distance maintain the thickness of at least one of the plurality of sprocket teeth, while the addendum chamfer ensures smooth engagement of at least one of the plurality of sprocket teeth with the bicycle chain. Therefore, the durability of the bicycle sprocket can be improved.

[0030] In accordance with a fourteenth aspect of the present invention, the bicycle sprocket according to the thirteenth aspect is configured so that the tooth tip has a circumferentially upstream tooth tip portion and a circumferentially downstream tooth tip portion opposite to the circumferential upstream tooth tip portion in a circumferential direction relative to the rotational center axis and relative to the driving rotational direction. The circumferential upstream tooth tip portion has a convexly curved portion configured to contact a chain roller of a bicycle chain during a running operation of the bicycle.

[0031] With the bicycle sprocket according to the fourteenth aspect, the convex curved portion further reduces wear of at least one of the plurality of sprocket teeth. Therefore, the durability of the bicycle sprocket can be reliably improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] A fuller understanding of the present invention together with many of its attendant advantages may be readily obtained by reference to the following detailed description taken in conjunction with the accompanying drawings.

[0033] Figure 1 is a schematic diagram of a bicycle including a bicycle sprocket assembly according to one embodiment.

[0034] Figure 2 yes Figure 1 is a side elevation view of a bicycle sprocket assembly for the bicycle shown in .

[0035] Figure 3It is along Figure 2 An exploded sectional view of a bicycle sprocket assembly taken along line III-III.

[0036] Figures 4 to 13 yes Figure 2 A side elevation view of a bicycle sprocket of the bicycle sprocket assembly is shown in FIG.

[0037] Figure 14 yes Figures 11 to 13 A side elevation view of a bicycle sprocket of the bicycle sprocket assembly is shown in FIG.

[0038] Figure 15 It is along Figure 14 A cross-sectional view of a bicycle sprocket assembly taken along line XV-XV.

[0039] Figure 16 yes Figure 11 Another side elevation view of the bicycle sprocket shown in .

[0040] Figure 17 yes Figure 12 Another side elevation view of the bicycle sprocket shown in .

[0041] Figure 18 yes Figure 13 Another side elevation view of the bicycle sprocket shown in .

[0042] Figure 19 yes Figure 11 An enlarged side elevation view of a bicycle sprocket is shown in FIG.

[0043] Figure 20 It is along Figure 19 A cross-sectional view of a bicycle sprocket taken along line XX-XX.

[0044] Figure 21 It is a cross-sectional view of a bicycle sprocket according to a modification.

[0045] Figure 22 It is along Figure 11 A cross-sectional view of a bicycle sprocket taken along line XXII-XXII.

[0046] Figure 23 It is along Figure 19 A cross-sectional view of a bicycle sprocket taken along line XXIII-XXIII.

[0047] Figure 24 It is along Figure 19 A cross-sectional view of a bicycle sprocket taken along line XXIV-XXIV.

[0048] Figure 25 yes Figure 2A side elevation view of a bicycle sprocket of the bicycle sprocket assembly is illustrated in FIG.

[0049] Figure 26 It is along Figure 25 A cross-sectional view of a bicycle sprocket taken along line XXVI-XXVI.

[0050] Figure 27 yes Figure 25 An enlarged side elevation view of a bicycle sprocket is shown in FIG.

[0051] Figure 28 yes Figure 25 Another enlarged side elevation view of the bicycle sprocket shown in . DETAILED DESCRIPTION

[0052] The embodiments will now be described with reference to the drawings, wherein like reference numerals designate corresponding or identical elements throughout the various views.

[0053] like Figure 1 As shown, a bicycle 2 includes a bicycle drive train 10. The bicycle drive train 10 includes a bicycle hub assembly 12 and a bicycle sprocket assembly 14. The bicycle hub assembly 12 is fixed to a bicycle frame BF. The bicycle sprocket assembly 14 is mounted on the bicycle hub assembly 12. The bicycle sprocket assembly 14 is rotatably supported by the bicycle hub assembly 12 relative to the bicycle frame BF about a rotational center axis A1. The bicycle 2 has an axial center plane CP.

[0054] The bicycle drivetrain 10 also includes a crank assembly 18 and a bicycle chain 20. The crank assembly 18 includes a crank axle 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 fixed to the crank axle 22. The front sprocket 27 is fixed to at least one of the crank axle 22 and the right crank arm 24. The bicycle chain 20 engages with the front sprocket 27 and the bicycle sprocket assembly 14 to transmit pedaling force from the front sprocket 27 to the bicycle sprocket assembly 14. The crank assembly 18 includes the front sprocket 27 as a single sprocket in this embodiment. However, the crank assembly 18 may include multiple front sprockets. The bicycle sprocket assembly 14 is a rear sprocket assembly. However, the structure of the bicycle sprocket assembly 14 can also be applied to the front sprocket.

[0055] As used herein, the following directional terms, such as "front," "rear," "forward," "backward," "left," "right," "lateral," "upward," and "downward," and any other similar directional terms, refer to directions based on a user (e.g., a rider) sitting on a bicycle seat (not shown) and facing handlebars (not shown). Accordingly, these terms, as utilized to describe the bicycle sprocket assembly 14, should be interpreted relative to a bicycle equipped with the bicycle sprocket assembly 14 as used in an upright riding position on a horizontal surface.

[0056] like Figure 2 As shown, the bicycle sprocket assembly 14 is configured to engage with the bicycle chain 20 to transmit a driving rotational force F1 between the bicycle chain 20 and the bicycle sprocket assembly 14 during pedaling. The bicycle sprocket assembly 14 rotates in a driving rotational direction D11 about a rotational center axis A1 during pedaling. The driving rotational direction D11 is defined as being along a circumferential direction D1 of the bicycle hub assembly 12 or the bicycle sprocket assembly 14. The counter-rotational direction D12 is the opposite direction of the driving rotational direction D11 and is defined as being along the circumferential direction D1.

[0057] The bicycle sprocket assembly 14 includes a plurality of bicycle sprockets SP. The plurality of bicycle sprockets SP is configured to engage with the bicycle chain 20 to transmit a driving rotational force F1 between the bicycle chain 20 and the bicycle sprocket assembly 14 during pedaling. In the present embodiment, the plurality of bicycle sprockets SP includes bicycle sprockets SP1 to SP11. Each of the bicycle sprockets SP1 to SP11 is configured to engage with the bicycle chain 20 to transmit a driving rotational force F1 between the bicycle chain 20 and the bicycle sprocket assembly 14 during pedaling. However, the total number of bicycle sprockets SP is not limited to the present embodiment.

[0058] like Figure 3 As shown, the bicycle sprockets SP1 to SP11 are arranged in an axial direction D2 relative to the rotation center axis A1. The bicycle sprockets are coupled to each other by fasteners. The bicycle sprocket assembly 14 further includes a locking member 32. The locking member 32 is fixed to the bicycle hub assembly 12 ( Figure 1 ) of the sprocket support body, with the sprocket support body ( Figure 1 ) holds the bicycle sprocket assembly 14.

[0059] The bicycle sprocket assembly 14 includes a plurality of coupling rods 34, a plurality of coupling members 35, and a plurality of spacers 36. The plurality of coupling rods 34 are configured to couple at least two of the bicycle sprockets SP1 to SP11. In this embodiment, the plurality of coupling rods 34 are configured to couple sprockets SP2 to SP8. The plurality of coupling members 35 are configured to connect sprockets SP1 and SP2. The spacers 36 are disposed between adjacent two of the plurality of sprockets SP2 to SP9 in the axial direction D2 to provide an appropriate axial space between the two adjacent sprockets.

[0060] In this embodiment, the bicycle sprockets SP1 and SP2 may also be referred to as the first sprocket SP1 and the second sprocket SP2. The bicycle sprockets SP2 and SP3 may also be referred to as the first sprocket SP2 and the second sprocket SP3. The bicycle sprockets SP3 and SP4 may also be referred to as the first sprocket SP3 and the second sprocket SP4. The bicycle sprockets SP4 and SP5 may also be referred to as the first sprocket SP4 and the second sprocket SP5. The bicycle sprockets SP5 and SP6 may also be referred to as the first sprocket SP5 and the second sprocket SP6. The bicycle sprockets SP6 and SP7 may also be referred to as the first sprocket SP6 and the second sprocket SP7. The bicycle sprockets SP7 and SP8 may also be referred to as the first sprocket SP7 and the second sprocket SP8. The bicycle sprockets SP8 and SP9 may also be referred to as the first sprocket SP8 and the second sprocket SP9. The bicycle sprockets SP9 and SP10 may also be referred to as the first sprocket SP9 and the second sprocket SP10. The bicycle sprockets SP10 and SP11 may also be referred to as the first sprocket SP10 and the second sprocket SP11.

[0061] In other words, the bicycle sprocket assembly 14 includes a first sprocket SP1 and a second sprocket SP2. The bicycle sprocket assembly 14 includes a first sprocket SP2 and a second sprocket SP3. The bicycle sprocket assembly 14 includes a first sprocket SP3 and a second sprocket SP4. The bicycle sprocket assembly 14 includes a first sprocket SP4 and a second sprocket SP5. The bicycle sprocket assembly 14 includes a first sprocket SP5 and a second sprocket SP6. The bicycle sprocket assembly 14 includes a first sprocket SP6 and a second sprocket SP7. The bicycle sprocket assembly 14 includes a first sprocket SP7 and a second sprocket SP8. The bicycle sprocket assembly 14 includes a first sprocket SP8 and a second sprocket SP9. The bicycle sprocket assembly 14 includes a first sprocket SP9 and a second sprocket SP10. The bicycle sprocket assembly 14 includes a first sprocket SP10 and a second sprocket SP11.

[0062] like Figure 4 As shown, a bicycle 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. The plurality of sprocket teeth SP1B are disposed on the outer periphery of the sprocket body SP1A. The plurality of sprocket teeth SP1B define a maximum tooth tip diameter DM1. The sprocket body SP1A may also be referred to as the first or second sprocket body SP1A. The plurality of sprocket teeth SP1B may also be referred to as the first or second sprocket teeth SP1B.

[0063] like Figure 5As shown, a bicycle 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. The plurality of sprocket teeth SP2B are disposed on the outer periphery of the sprocket body SP2A. The plurality of sprocket teeth SP2B define a maximum tooth tip diameter DM2. The sprocket body SP2A may also be referred to as the first or second sprocket body SP2A. The plurality of sprocket teeth SP2B may also be referred to as the first or second sprocket teeth SP2B.

[0064] like Figure 6 As shown, a bicycle 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. The plurality of sprocket teeth SP3B are disposed on the outer periphery of the sprocket body SP3A. The plurality of sprocket teeth SP3B define a maximum tooth tip diameter DM3. The sprocket body SP3A may also be referred to as the first or second sprocket body SP3A. The plurality of sprocket teeth SP3B may also be referred to as the first or second sprocket teeth SP3B.

[0065] like Figure 7 As shown, a bicycle 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. The plurality of sprocket teeth SP4B are disposed on the outer periphery of the sprocket body SP4A. The plurality of sprocket teeth SP4B define a maximum tooth tip diameter DM4. The sprocket body SP4A may also be referred to as the first or second sprocket body SP4A. The plurality of sprocket teeth SP4B may also be referred to as the first or second sprocket teeth SP4B.

[0066] like Figure 8 As shown, a bicycle 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. The plurality of sprocket teeth SP5B are disposed on the outer periphery of the sprocket body SP5A. The plurality of sprocket teeth SP5B define a maximum tooth tip diameter DM5. The sprocket body SP5A may also be referred to as the first or second sprocket body SP5A. The plurality of sprocket teeth SP5B may also be referred to as the first or second sprocket teeth SP5B.

[0067] like Figure 9 As shown, a bicycle 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. The plurality of sprocket teeth SP6B are disposed on the outer periphery of the sprocket body SP6A. The plurality of sprocket teeth SP6B define a maximum tooth tip diameter DM6. The sprocket body SP6A may also be referred to as the first or second sprocket body SP6A. The plurality of sprocket teeth SP6B may also be referred to as the first or second sprocket teeth SP6B.

[0068] like Figure 10As shown, a bicycle 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. The plurality of sprocket teeth SP7B are disposed on the outer periphery of the sprocket body SP7A. The plurality of sprocket teeth SP7B define a maximum tooth tip diameter DM7. The sprocket body SP7A may also be referred to as the first or second sprocket body SP7A. The plurality of sprocket teeth SP7B may also be referred to as the first or second sprocket teeth SP7B.

[0069] like Figure 2 and Figures 4 to 10 As shown, the maximum tooth tip diameter DM1 is larger than each of the maximum tooth tip diameters DM2 to DM7. The maximum tooth tip diameter DM2 is larger than each of the maximum tooth tip diameters DM3 to DM7. The maximum tooth tip diameter DM3 is larger than each of the maximum tooth tip diameters DM4 to DM7. The maximum tooth tip diameter DM4 is larger than each of the maximum tooth tip diameters DM5 to DM7. The maximum tooth tip diameter DM5 is larger than each of the maximum tooth tip diameters DM6 and DM7. The maximum tooth tip diameter DM6 is larger than the maximum tooth tip diameter DM7.

[0070] like Figure 11 As shown, the first sprocket SP8 includes a first sprocket body SP8A and a plurality of first sprocket teeth SP8B. The plurality of first sprocket teeth SP8B extend radially outward from the first sprocket body SP8A. The plurality of first sprocket teeth SP8B are arranged on the outer periphery of the first sprocket body SP8A. The plurality of first sprocket teeth SP8B define a first maximum tooth tip diameter DM8. The first maximum tooth tip diameter DM8 is smaller than each of the maximum tooth tip diameters DM1 to DM7 (e.g., see Figures 4 to 10 ).

[0071] The first sprocket body SP8A may also be referred to as the sprocket body SP8A. The first sprocket teeth SP8B may also be referred to as the sprocket teeth SP8B. Thus, the bicycle 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. The plurality of sprocket teeth SP8B are disposed on the outer periphery of the sprocket body SP8A.

[0072] The bicycle sprocket SP8 has a pitch circle PC8. When viewed along the rotational center axis A1, the pitch circle PC8 is defined by the center of the rollers of the bicycle chain 20 that contact the plurality of sprocket teeth SP8B during pedaling. The pitch circle PC8 has a pitch circle diameter PC8D.

[0073] like Figure 12As shown, the second sprocket SP9 includes a second sprocket body SP9A and a plurality of second sprocket teeth SP9B. The plurality of second sprocket teeth SP9B extend radially outward from the second sprocket body SP9A. The plurality of second sprocket teeth SP9B are arranged on the outer periphery of the second sprocket body SP9A. The plurality of second sprocket teeth SP9B define a second maximum tooth tip diameter DM9.

[0074] The second sprocket body SP9A may also be referred to as the sprocket body SP9A. The second sprocket teeth SP9B may also be referred to as the sprocket teeth SP9B. Thus, the bicycle 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. The plurality of sprocket teeth SP9B are disposed on the outer periphery of the sprocket body SP9A.

[0075] The bicycle sprocket SP9 has a pitch circle PC9. When viewed along the rotational center axis A1, the pitch circle PC9 is defined by the center of the rollers of the bicycle chain 20 that contact the plurality of sprocket teeth SP9B during pedaling. The pitch circle PC9 has a pitch circle diameter PC9D.

[0076] like Figure 12 As shown, if the bicycle sprockets SP9 and SP10 are referred to as a first sprocket SP9 and a second sprocket SP10, the first sprocket SP9 includes a first sprocket body SP9A and a plurality of first sprocket teeth SP9B. The plurality of first sprocket teeth SP9B are arranged on the outer periphery of the first sprocket body SP9A. The plurality of first sprocket teeth SP9B define a first maximum tooth tip diameter DM9.

[0077] like Figure 13 As shown, if the bicycle sprockets SP9 and SP10 are referred to as a first sprocket SP9 and a second sprocket SP10, the second sprocket SP10 includes a second sprocket body SP10A and a plurality of second sprocket teeth SP10B. The plurality of second sprocket teeth SP10B extend radially outward from the second sprocket body SP10A. The plurality of second sprocket teeth SP10B are arranged on an outer periphery of the second sprocket body SP10A. The plurality of second sprocket teeth SP10B define a second maximum tooth tip diameter DM10.

[0078] The second sprocket body SP10A may also be referred to as the sprocket body SP10A. The second sprocket teeth SP10B may also be referred to as the sprocket teeth SP10B. Thus, the bicycle 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. The plurality of sprocket teeth SP10B are disposed on the outer periphery of the sprocket body SP10A.

[0079] The bicycle sprocket SP10 has a pitch circle PC10. The pitch circle PC10 is defined by the center of the rollers of the bicycle chain 20 that contact the plurality of sprocket teeth SP10B during pedaling, as viewed along the rotational center axis A1. The pitch circle PC10 has a pitch circle diameter PC10D.

[0080] like Figure 14 As shown, the second maximum tooth tip diameter DM9 is smaller than the first maximum tooth tip diameter DM8. The second maximum tooth tip diameter DM10 is smaller than the first maximum tooth tip diameter DM9. The total number of sprocket teeth SP8B is 17. The total number of sprocket teeth SP9B is 15. The total number of sprocket teeth SP10B is 13. However, the total number of sprocket teeth SP8B is not limited to 17. The total number of sprocket teeth SP9B is not limited to 15. The total number of sprocket teeth SP10B is not limited to 13.

[0081] like Figure 15 As shown, the first sprocket SP8 includes a first sprocket inward surface SP8C and a first sprocket outward surface SP8D. The first sprocket inward surface SP8C is configured to face the axial center plane CP of the bicycle 2 (e.g., see FIG. 1 ) when the bicycle sprocket assembly 14 is mounted on the bicycle 2. Figure 1 The first sprocket outward surface SP8D is disposed on an opposite side of the first sprocket inward surface SP8C in the axial direction D2 with respect to the rotational center axis A1 of the bicycle sprocket SP8.

[0082] The bicycle sprocket SP8 includes an inboard sprocket side SP8E and an outboard sprocket side SP8F. The inboard sprocket side SP8E is located closer to the axial center plane CP of the bicycle 2 than the outboard sprocket side SP8F when the bicycle sprocket SP8 is mounted on the bicycle 2. The outboard sprocket side SP8F is located on the opposite side of the inboard sprocket side SP8E in the axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP8. A first inboard sprocket surface SP8C is located on the inboard sprocket side SP8E. A first outboard sprocket surface SP8D is located on the outboard sprocket side SP8F.

[0083] The second sprocket SP9 is adjacent to the first sprocket SP8 in the axial direction D2, with no other sprocket interposed therebetween. The second sprocket SP9 includes a second sprocket inwardly facing surface SP9C and a second sprocket outwardly facing surface SP9D. The second sprocket inwardly facing surface SP9C is configured to face the axial center plane CP of the bicycle when installed. The second sprocket outwardly facing surface SP9D is located on the opposite side of the second sprocket inwardly facing surface SP9C in the axial direction D2.

[0084] The bicycle sprocket SP9 includes an inboard sprocket side SP9E and an outboard sprocket side SP9F. The inboard sprocket side SP9E is located closer to the axial center plane CP of the bicycle 2 than the outboard sprocket side SP9F when the bicycle sprocket SP9 is mounted on the bicycle 2. The outboard sprocket side SP9F is located on the opposite side of the inboard sprocket side SP9E in the axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP9. A second inboard sprocket surface SP9C is located on the inboard sprocket side SP9E. A second outboard sprocket surface SP9D is located on the outboard sprocket side SP9F.

[0085] If the bicycle sprockets SP9 and SP10 are referred to as a first sprocket SP9 and a second sprocket SP10, the first sprocket SP9 includes a first sprocket inwardly facing surface SP9C and a first sprocket outwardly facing surface SP9D. The first sprocket inwardly facing surface SP9C is configured to face an axial center plane CP (see FIG. 1 ) of the bicycle 2 when the bicycle sprocket assembly 14 is mounted on the bicycle 2. Figure 1 The first sprocket outward surface SP9D is disposed on an opposite side of the first sprocket inward surface SP9C in the axial direction D2 with respect to the rotational center axis A1 of the bicycle sprocket SP9.

[0086] The second sprocket SP10 is adjacent to the first sprocket SP9 in the axial direction D2, with no other sprocket interposed therebetween. The second sprocket SP10 includes a second sprocket inwardly facing surface SP10C and a second sprocket outwardly facing surface SP10D. The second sprocket inwardly facing surface SP10C is configured to face the axial center plane CP of the bicycle 2 when mounted. The second sprocket outwardly facing surface SP10D is located on the opposite side of the second sprocket inwardly facing surface SP10C.

[0087] The bicycle sprocket SP10 includes an inboard sprocket side SP10E and an outboard sprocket side SP10F. The inboard sprocket side SP10E is located closer to the axial center plane CP of the bicycle 2 than the outboard sprocket side SP10F when the bicycle sprocket SP10 is mounted on the bicycle 2. The outboard sprocket side SP10F is located on the opposite side of the inboard sprocket side SP10E in the axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP10. A second inboard sprocket surface SP10C is located on the inboard sprocket side SP10E. A second outboard sprocket surface SP10D is located on the outboard sprocket side SP10F.

[0088] The bicycle chain 20 includes a pair of opposing outer link plates 20A and a pair of opposing inner link plates 20B. The pair of opposing outer link plates 20A includes an axially inner link plate 20C and an axially outer link plate 20D. The pair of opposing inner link plates 20B includes an axially inner link plate 20E and an axially outer link plate 20F. When the bicycle chain 20 is assembled, the axially inner link plates 20C and the axially outer link plates 20D of the pair of opposing outer link plates 20A are spaced apart from each other in the axial direction D2. When the bicycle chain 20 is assembled, the axially inner link plates 20E and the axially outer link plates 20F of the pair of opposing inner link plates 20B are spaced apart from each other in the axial direction D2.

[0089] Each of the plurality of sprocket teeth SP8B is configured to enter each of an outer chain space 20G defined between a pair of opposing outer link plates 20A of the bicycle chain 20 and an inner chain space 20H defined between a pair of opposing inner link plates 20B of the bicycle chain 20. Each of the plurality of sprocket teeth SP9B is configured to enter each of the outer chain space 20G and the inner chain space 20H. Each of the plurality of sprocket teeth SP10B is configured to enter each of the outer chain space 20G and the inner chain space 20H.

[0090] In this embodiment, the axial length 20J of the inner link space 20H is equal to or greater than 2.32 mm. The bicycle chain 20 has an outer distance 20K defined as the distance between the axially outer surfaces of the pair of opposing outer link plates 20A in the axial direction D2. The outer distance 20K of the bicycle chain 20 is 5.62 mm. However, the axial length 20J and the outer distance 20K of the inner link space 20H are not limited to the above values.

[0091] The first sprocket SP8 includes an axial space AS8. When one of the plurality of second sprocket teeth SP9B is engaged between the axially inward inner link plate 20E and the axially outward inner link plate 20F of a pair of opposing inner link plates 20B in the axial direction D2, and the second sprocket-outward surface SP9D of the one of the plurality of second sprocket teeth SP9B contacts the axially outward inner link plate 20F of the pair of opposing inner link plates 20B of the bicycle chain 20, the axial space AS8 is defined as the space between the first sprocket-outward surface SP8D of the one of the plurality of first sprocket teeth SP8B and the axially outward inner link plates 20C of the pair of opposing outer link plates 20A of the bicycle chain 20 in the axial direction D2. In the present embodiment, the axial space AS8 is greater than 0 mm and equal to or less than 0.15 mm. In the present embodiment, the axial space AS8 is 0.08 mm. However, the axial space AS8 is not limited to the present embodiment and the above range. The value and range of the axial space AS8 can be applied to other first and second sprockets in the plurality of bicycle sprockets SP.

[0092] The first sprocket SP9 includes an axial space AS9. When one of the plurality of second sprocket teeth SP10B is engaged in the axial direction D2 between the axially inward inner link plate 20E and the axially outward inner link plate 20F of a pair of opposing inner link plates 20B, and the second sprocket-outward surface SP10D of the one of the plurality of second sprocket teeth SP10B contacts the axially outward inner link plate 20F of the pair of opposing inner link plates 20B of the bicycle chain 20, the axial space AS9 is defined as the space between the first sprocket-outward surface SP9D of the one of the plurality of first sprocket teeth SP9B and the axially outward inner link plates 20C of the pair of opposing outer link plates 20A of the bicycle chain 20 in the axial direction D2. In the present embodiment, the axial space AS9 is greater than 0 mm and equal to or less than 0.15 mm. In the present embodiment, the axial space AS9 is 0.08 mm. However, the axial space AS9 is not limited to the above value and range. The value and range of the axial space AS9 can also be applied to other first and second sprockets in the plurality of bicycle sprockets SP.

[0093] An axial distance AD8 is defined between the sprocket outward surface SP8D of the bicycle sprocket SP8 and the sprocket inward surface SP9C of the bicycle sprocket SP9 in the axial direction D2. An axial distance AD9 is defined between the sprocket outward surface SP9D of the bicycle sprocket SP9 and the sprocket inward surface SP10C of the bicycle sprocket SP10 in the axial direction D2. An additional axial distance AD89 is defined between the sprocket outward surface SP8D of the bicycle sprocket SP8 and the sprocket inward surface SP10C of the bicycle sprocket SP10 in the axial direction D2. An axial sprocket pitch PT8 is defined between the axial center plane AP8 of the bicycle sprocket SP8 and the axial center plane AP9 of the bicycle sprocket SP9 in the axial direction D2. An axial sprocket pitch PT9 is defined between the axial center plane AP9 of the bicycle sprocket SP9 and the axial center plane AP10 of the bicycle sprocket SP10 in the axial direction D2.

[0094] An axial center plane AP8 of the bicycle sprocket SP8 is defined as bisecting the axial width of the sprocket body SP8A of the bicycle sprocket SP8 in the axial direction D2 and being perpendicular to the axial direction D2. An axial center plane AP9 of the bicycle sprocket SP9 is defined as bisecting the axial width of the sprocket body SP9A of the bicycle sprocket SP9 in the axial direction D2 and being perpendicular to the axial direction D2. An axial center plane AP10 of the bicycle sprocket SP10 is defined as bisecting the axial width of the sprocket body SP10A of the bicycle sprocket SP10 in the axial direction D2 and being perpendicular to the axial direction D2.

[0095] In this embodiment, the axial distance AD8 is 2.1 mm. The axial distance AD9 is 2.1 mm. The additional axial distance AD89 is 6.15 mm. The axial sprocket pitch PT8 is 4.05 mm. The difference between the additional axial distance AD89 and the outer distance 20K of the bicycle chain 20 is 0.53 mm. However, the axial distance AD8, the axial distance AD9, the axial sprocket pitch PT8, and the difference between the additional axial distance AD89 and the outer distance 20K are not limited to the above values. The values ​​of the axial distance AD8, the axial distance AD9, the axial sprocket pitch PT8, and the difference between the additional axial distance AD89 and the outer distance 20K can be applied to other sprockets among the plurality of bicycle sprockets SP.

[0096] like Figure 11 As shown, the bicycle sprocket SP8 further includes an upshift facilitating section SP8G and a downshift facilitating section SP8H. The first sprocket SP8 includes the upshift facilitating section SP8G and the downshift facilitating section SP8H.

[0097] The upshift promoting section SP8G is configured to promote the bicycle chain 20 from the first sprocket SP8 toward the second sprocket SP9 (see, for example, FIG. Figure 15 ) upshift operation of the bicycle chain 20. The upshift promoting section SP8G is intentionally designed to promote the upshift operation of the bicycle chain 20 from the first sprocket SP8 to the second sprocket SP9. The second sprocket SP9 may also be referred to as the small sprocket SP9. Therefore, the upshift promoting section SP8G is configured to promote the bicycle chain 20 from the bicycle sprocket SP8 to the small sprocket SP9 (see, for example, FIG. Figure 15 In an upshift operation of a gear shift, the small sprocket SP9 is adjacent to the bicycle sprocket SP8 in an axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP8 without another sprocket therebetween. The upshift promoting section SP8G is intentionally designed to promote an upshift operation of shifting the bicycle chain 20 from the bicycle sprocket SP8 toward the small sprocket SP9.

[0098] The downshift facilitating section SP8H is configured to facilitate the bicycle chain 20 to shift from the second sprocket SP9 (see, for example, Figure 15 ) toward the first sprocket SP8. The downshift facilitating section SP8H is intentionally designed to facilitate a downshifting operation of the bicycle chain 20 from the second sprocket SP9 toward the first sprocket SP8. Therefore, the downshift facilitating section SP8H is configured to facilitate the bicycle chain 20 from the small sprocket SP9 (see, for example, Figure 15 The downshift promoting section SP8H is intentionally designed to promote a downshifting operation of the bicycle chain 20 from the small sprocket SP9 toward the bicycle sprocket SP8.

[0099] The downshift facilitating section SP8H is positioned upstream of the upshift facilitating section SP8G in the circumferential direction D1. The downshift facilitating section SP8H is positioned upstream of the upshift facilitating section SP8G in the circumferential direction D1 relative to the rotational center axis A1 of the bicycle sprocket and in the drive rotational direction D11. The downshift facilitating section SP8H is positioned upstream of the upshift facilitating section SP8G in the drive rotational direction D11, and no other shift facilitating section exists between the upshift facilitating section SP8G and the downshift facilitating section SP8H.

[0100] The upshift facilitation section SP8G is formed by the first teeth group TG8A of the plurality of sprocket teeth SP8B. The downshift facilitation section SP8H is formed by the second teeth group TG8B of the plurality of sprocket teeth SP8B. The second teeth group TG8B is completely different from the first teeth group TG8A. The first teeth group TG8A of the upshift facilitation section SP8G and the second teeth group TG8B of the downshift facilitation section SP8H are adjacent to each other, with no teeth interposed therebetween.

[0101] The first teeth group TG8A includes upshift teeth SP8G1 and SP8G2, and upshift facilitating teeth SP8G3 and SP8G4. The second teeth group TG8B includes downshift facilitating teeth SP8H1 and SP8H2, and downshift teeth SP8H3 and SP8H4. The total number of sprocket teeth SP8B in the second teeth group TG8B is equal to the total number of sprocket teeth SP8B in the first teeth group TG8A. However, the total number of sprocket teeth SP8B in the second teeth group TG8B may differ from the total number of sprocket teeth SP8B in the first teeth group TG8A.

[0102] The total number of sprocket teeth SP8B arranged from the downstream end of the downshift promotion section SP8H to the upstream end of the upshift promotion section SP8G in the reverse rotational direction D12 is greater than the total number of sprocket teeth SP8B arranged from the downstream end of the downshift promotion section SP8H to the upstream end of the upshift promotion section SP8G in the driving rotational direction D11. In the present embodiment, the total number of sprocket teeth SP8B arranged from the downstream end of the downshift promotion section SP8H to the upstream end of the upshift promotion section SP8G in the reverse rotational direction D12 is nine. The total number of sprocket teeth SP8B arranged from the downstream end of the downshift promotion section SP8H to the upstream end of the upshift promotion section SP8G in the driving rotational direction D11 is zero. However, the positional relationship between the upshift promotion section SP8G and the downshift promotion section SP8H is not limited to the present embodiment.

[0103] The upshift teeth SP8G2 are configured to engage with the outer chain spaces 20G (see FIG. 2 ) of the opposite outer link plates 20A of the bicycle chain 20 when the upshift facilitating teeth SP8G3 are engaged with the outer chain spaces 20G (see FIG. 2 ) of the opposite outer link plates 20A of the bicycle chain 20. Figure 15 ), in the first state of the bicycle chain 20, the opposing inner link plates 20B of the bicycle chain 20 are first derailed from the bicycle sprocket SP8 during an upshift operation.

[0104] The upshift tooth SP8G1 includes an upshift recess SP8G1R disposed on the sprocket-outward side SP8F to facilitate an upshift operation. The upshift recess SP8G1R is configured to derail the opposing outer link plates 20A of the bicycle chain 20 during an upshift operation after the upshift tooth SP8G2 derails the opposing inner link plates 20B of the bicycle chain 20 from the bicycle sprocket SP8.

[0105] The upshift teeth SP8G2 include an upshift recess SP8G2R disposed on the sprocket-outward side SP8F to facilitate an upshift operation. The upshift recess SP8G2R is configured to first derail the opposing inner link plates 20B of the bicycle chain 20 during an upshift operation.

[0106] like Figure 16 As shown, the upshift promoting tooth SP8G3 includes an upshift promoting recess SP8G3R disposed on the inner side SP8E of the sprocket to promote upshifting. The upshift promoting recess SP8G3R is configured to promote the bicycle chain 20 to move toward the small sprocket SP9 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP8.

[0107] The upshift promoting tooth SP8G4 includes an upshift promoting recess SP8G4R disposed on the inner side SP8E of the sprocket to promote upshifting. The upshift promoting recess SP8G4R is configured to promote the bicycle chain 20 to move toward the small sprocket SP9 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP8.

[0108] like Figure 11 As shown, the downshift facilitating tooth SP8H1 includes a downshift facilitating recess SP8H1R disposed on the outer side SP8F of the sprocket to facilitate downshifting. The downshift facilitating recess SP8H1R is configured to reduce interference between the bicycle sprocket SP8 and the bicycle chain 20 during downshifting. The downshift facilitating recess SP8H1R is configured to facilitate movement of the bicycle chain 20 from the small sprocket SP9 toward the bicycle sprocket SP8 during downshifting, while the bicycle chain 20 is engaged with the small sprocket SP9.

[0109] The downshift facilitating tooth SP8H2 includes a downshift facilitating recess SP8H2R disposed on the sprocket's outer side SP8F to facilitate downshifting. The downshift facilitating recess SP8H2R is configured to reduce interference between the bicycle sprocket SP8 and the bicycle chain 20 during downshifting. The downshift facilitating recess SP8H2R is configured to facilitate movement of the bicycle sprocket from the small sprocket SP9 toward the bicycle sprocket SP8 during downshifting, while the bicycle chain 20 is meshed with the small sprocket SP9.

[0110] The downshift teeth SP8H3 include a downshift recess SP8H3R disposed on the outer side SP8F of the sprocket to facilitate downshifting. The downshift recess SP8H3R is configured to facilitate meshing of the bicycle sprocket SP8 with the bicycle chain 20 during downshifting.

[0111] like Figure 16 As shown, the downshift tooth SP8H4 is configured to catch the opposing outer link plate 20A of the bicycle chain 20 during a downshift operation if one of the opposing inner link plates 20B contacts the downshift tooth SP8H3 during the downshift operation. The downshift tooth SP8H4 includes a downshift recess SP8H4R disposed on the sprocket inner side SP8E to facilitate the downshift operation. The downshift recess SP8H4R is configured to facilitate catching the opposing outer link plate 20A of the bicycle chain 20 at the downshift tooth SP8H4 during a downshift operation.

[0112] like Figure 11 As shown, the bicycle sprocket SP8 further includes an additional upshift facilitating section SP8P. The additional upshift facilitating section SP8P is configured to facilitate the bicycle chain 20 from the first sprocket SP8 toward the second sprocket SP9 (see, for example, FIG. Figure 15 ) upshift operation of the bicycle chain 20 from the first sprocket SP8 toward the second sprocket SP9. The additional upshift facilitating section SP8P is intentionally designed to facilitate the upshift operation of the bicycle chain 20 from the first sprocket SP8 toward the second sprocket SP9. The additional upshift facilitating section SP8P is configured to facilitate the bicycle chain 20 from the bicycle sprocket SP8 toward the small sprocket SP9 (see, for example, FIG. Figure 15 In an upshifting operation of a gear shift, the small sprocket SP9 is adjacent to the bicycle sprocket SP8 in an axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP8 without another sprocket therebetween. The additional upshift promoting section SP8P is intentionally designed to promote an upshifting operation of a gear shift from the bicycle sprocket SP8 toward the small sprocket SP9.

[0113] The additional upshift facilitation section SP8P is formed by the third tooth group TG8C of the plurality of sprocket teeth SP8B. The first tooth group TG8A is completely different from the third tooth group TG8C. The second tooth group TG8B is completely different from the third tooth group TG8C. The third tooth group TG8C of the additional upshift facilitation section SP8P is adjacent to the second tooth group TG8B of the downshift facilitation section SP8H, with no other teeth therebetween.

[0114] The third teeth group TG8C includes additional upshift teeth SP8P1 to SP8P4. The total number of sprocket teeth SP8B in the first teeth group TG8A is equal to the total number of sprocket teeth SP8B in the third teeth group TG8C. The total number of sprocket teeth SP8B in the second teeth group TG8B is equal to the total number of sprocket teeth SP8B in the third teeth group TG8C. However, the total number of sprocket teeth SP8B in the first teeth group TG8A may differ from the total number of sprocket teeth SP8B in the third teeth group TG8C. The total number of sprocket teeth SP8B in the second teeth group TG8B may also differ from the total number of sprocket teeth SP8B in the third teeth group TG8C.

[0115] The upshift facilitating teeth SP8P3 are configured to engage with the outer chain spaces 20G of the opposing outer link plates 20A of the bicycle chain 20 (see, for example, FIG. 2 ). Figure 15 ), the opposing inner link plates 20B of the bicycle chain 20 are derailed from the bicycle sprocket SP8 during an upshift operation.

[0116] The upshift tooth SP8P1 includes an upshift recess SP8P1R disposed on the sprocket-outward side SP8F to facilitate an upshift operation. The upshift recess SP8P1R is configured to derail the opposing outer link plates 20A of the bicycle chain 20 during an upshift operation after the upshift facilitating tooth SP8P3 derails the opposing inner link plates 20B of the bicycle chain 20 from the bicycle sprocket SP8.

[0117] The upshift teeth SP8P2 include an upshift recess SP8P2R disposed on the sprocket-outward side SP8F to facilitate upshifting. The upshift recess SP8P2R is configured to first derail the opposing inner link plates 20B of the bicycle chain 20 during an upshift operation when the upshift facilitating teeth SP8P3 are engaged in the outer chain spaces 20G of the opposing outer link plates 20A of the bicycle chain 20.

[0118] like Figure 16 As shown, the upshift promoting tooth SP8P3 includes an upshift promoting recess SP8P3R disposed on the inner side SP8E of the sprocket to promote upshifting. The upshift promoting recess SP8P3R is configured to promote the bicycle chain 20 to move toward the small sprocket SP9 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP8.

[0119] The upshift promoting tooth SP8P4 includes an upshift promoting recess SP8P4R disposed on the inner side SP8E of the sprocket to promote upshifting. The upshift promoting recess SP8P4R is configured to promote the bicycle chain 20 to move toward the small sprocket SP9 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP8.

[0120] In the present embodiment, the bicycle sprocket SP8 further includes an additional upshift facilitating section SP8P. However, the additional upshift facilitating section SP8P may be omitted from the bicycle sprocket SP8.

[0121] like Figure 12 As shown, the bicycle sprocket SP9 further includes an upshift facilitating section SP9G and a downshift facilitating section SP9H. The first sprocket SP9 includes the upshift facilitating section SP9G and the downshift facilitating section SP9H.

[0122] The upshift promoting section SP9G is configured to promote the bicycle chain 20 from the first sprocket SP9 toward the second sprocket SP10 (see, for example, FIG. Figure 15 ) upshift operation. The upshift promoting section SP9G is intentionally designed to promote the upshift operation of the bicycle chain 20 from the first sprocket SP9 to the second sprocket SP10. The second sprocket SP10 may also be referred to as the small sprocket SP10. Therefore, the upshift promoting section SP9G is configured to promote the bicycle chain 20 from the bicycle sprocket SP9 to the small sprocket SP10 (see, for example, FIG. Figure 15 In an upshift operation of a gear shift, the small sprocket SP10 is adjacent to the bicycle sprocket SP9 in an axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP9 without another sprocket therebetween. The upshift promoting section SP9G is intentionally designed to promote an upshift operation of shifting the bicycle chain 20 from the bicycle sprocket SP9 toward the small sprocket SP10.

[0123] The downshift facilitating section SP9H is configured to facilitate the bicycle chain 20 to shift from the second sprocket SP10 (see, for example, Figure 15 ) toward the first sprocket SP9. The downshift facilitating section SP9H is intentionally designed to facilitate a downshifting operation of the bicycle chain 20 from the second sprocket SP10 toward the first sprocket SP9. Therefore, the downshift facilitating section SP9H is configured to facilitate the bicycle chain 20 from the small sprocket SP10 (see, for example, Figure 15 The downshift promoting section SP9H is intentionally designed to promote a downshifting operation of the bicycle chain 20 from the small sprocket SP10 toward the bicycle sprocket SP9.

[0124] The downshift facilitating section SP9H is positioned upstream of the upshift facilitating section SP9G in the circumferential direction D1. The downshift facilitating section SP9H is positioned upstream of the upshift facilitating section SP9G in the circumferential direction D1 relative to the rotational center axis A1 of the bicycle sprocket and in the driving rotational direction D11. The downshift facilitating section SP9H is positioned upstream of the upshift facilitating section SP9G in the driving rotational direction D11, and there is no other shift facilitating section between the upshift facilitating section SP9G and the downshift facilitating section SP9H.

[0125] The upshift facilitation section SP9G is formed by the first teeth group TG9A of the plurality of sprocket teeth SP9B. The downshift facilitation section SP9H is formed by the second teeth group TG9B of the plurality of sprocket teeth SP9B. The second teeth group TG9B is completely different from the first teeth group TG9A. The first teeth group TG9A of the upshift facilitation section SP9G and the second teeth group TG9B of the downshift facilitation section SP9H are adjacent to each other, with no teeth interposed therebetween.

[0126] The first teeth group TG9A includes upshift teeth SP9G1 and SP9G2 and upshift facilitating teeth SP9G3 and SP9G4. The second teeth group TG9B includes downshift facilitating teeth SP9H1 and SP9H2 and downshift teeth SP9H3 and SP9H4. The total number of sprocket teeth SP9B of the second teeth group TG9B is equal to the total number of sprocket teeth SP9B of the first teeth group TG9A. However, the total number of sprocket teeth SP9B of the second teeth group TG9B may differ from the total number of sprocket teeth SP9B of the first teeth group TG9A.

[0127] The total number of sprocket teeth SP9B arranged from the downstream end of the downshift promotion section SP9H to the upstream end of the upshift promotion section SP9G in the reverse rotational direction D12 is greater than the total number of sprocket teeth SP9B arranged from the downstream end of the downshift promotion section SP9H to the upstream end of the upshift promotion section SP9G in the drive rotational direction D11. In the present embodiment, the total number of sprocket teeth SP9B arranged from the downstream end of the downshift promotion section SP9H to the upstream end of the upshift promotion section SP9G in the reverse rotational direction D12 is seven. The total number of sprocket teeth SP9B arranged from the downstream end of the downshift promotion section SP9H to the upstream end of the upshift promotion section SP9G in the drive rotational direction D11 is zero. However, the positional relationship between the upshift promotion section SP9G and the downshift promotion section SP9H is not limited to the present embodiment.

[0128] The upshift teeth SP9G2 are configured to engage with the outer chain spaces 20G of the opposing outer link plates 20A of the bicycle chain 20 (see, for example, FIG. 2 ). Figure 15 ), in the first state of the bicycle chain 20, the opposing inner link plates 20B of the bicycle chain 20 are first derailed from the bicycle sprocket SP9 during an upshift operation.

[0129] The upshift tooth SP9G1 includes an upshift recess SP9G1R disposed on the sprocket-outward side SP9F to facilitate an upshift operation. The upshift recess SP9G1R is configured to derail the opposing outer link plates 20A of the bicycle chain 20 during an upshift operation if the upshift tooth SP9G2 derails the opposing inner link plates 20B of the bicycle chain 20 from the bicycle sprocket SP9.

[0130] The upshift teeth SP9G2 include an upshift recess SP9G2R disposed on the sprocket-outward side SP9F to facilitate an upshift operation. The upshift recess SP9G2R is configured to first derail the opposing inner link plates 20B of the bicycle chain 20 during an upshift operation.

[0131] like Figure 17 As shown, the upshift promoting tooth SP9G3 includes an upshift promoting recess SP9G3R disposed on the inner side SP9E of the sprocket to promote upshifting. The upshift promoting recess SP9G3R is configured to promote the bicycle chain 20 to move toward the small sprocket SP10 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP9.

[0132] The upshift promoting tooth SP9G4 includes an upshift promoting recess SP9G4R disposed on the inner side SP9E of the sprocket to promote upshifting. The upshift promoting recess SP9G4R is configured to promote the bicycle chain 20 to move toward the small sprocket SP10 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP9.

[0133] like Figure 12 As shown, the downshift facilitating tooth SP9H1 includes a downshift facilitating recess SP9H1R disposed on the outer side SP9F of the sprocket to facilitate downshifting. The downshift facilitating recess SP9H1R is configured to reduce interference between the bicycle sprocket SP9 and the bicycle chain 20 during downshifting. The downshift facilitating recess SP9H1R is configured to facilitate movement of the bicycle chain 20 from the small sprocket SP10 toward the bicycle sprocket SP9 during downshifting, while the bicycle chain 20 is engaged with the small sprocket SP10.

[0134] The downshift-facilitating tooth SP9H2 includes a downshift-facilitating recess SP9H2R disposed on the sprocket-outward side SP9F to facilitate downshifting. The downshift-facilitating recess SP9H2R is configured to reduce interference between the bicycle sprocket SP9 and the bicycle chain 20 during downshifting. The downshift-facilitating recess SP9H2R is configured to facilitate movement of the bicycle chain 20 from the small sprocket SP10 toward the bicycle sprocket SP9 during downshifting, while the bicycle chain 20 is engaged with the small sprocket SP10.

[0135] The downshift teeth SP9H3 include a downshift recess SP9H3R disposed on the sprocket outer side SP9F to facilitate downshifting. The downshift recess SP9H3R is configured to facilitate engagement of the bicycle sprocket SP9 with the bicycle chain 20 during a downshifting operation.

[0136] like Figure 17As shown, the downshift tooth SP9H4 is configured to catch the opposing outer link plate 20A of the bicycle chain 20 if one of the opposing inner link plates 20B contacts the downshift tooth SP9H3 during a downshift operation. The downshift tooth SP9H4 includes a downshift recess SP9H4R disposed on the sprocket inner side SP9E to facilitate the downshift operation. The downshift recess SP9H4R is configured to facilitate catching the opposing outer link plate 20A of the bicycle chain 20 at the downshift tooth SP9H4 during a downshift operation.

[0137] like Figure 13 As shown, the bicycle sprocket SP10 further includes an upshift facilitating section SP10G and a downshift facilitating section SP10H. The first sprocket SP10 includes the upshift facilitating section SP10G and the downshift facilitating section SP10H.

[0138] The upshift promoting section SP10G is configured to promote the bicycle chain 20 from the first sprocket SP10 toward the second sprocket SP11 (see, for example, FIG. Figure 3 ) upshift operation of shifting. The upshift facilitating section SP10G is intentionally designed to facilitate the upshift operation of the bicycle chain 20 from the first sprocket SP10 to the second sprocket SP11. The second sprocket SP11 may also be referred to as the small sprocket SP11. Therefore, the upshift facilitating section SP10G is configured to facilitate the bicycle chain 20 from the bicycle sprocket SP10 to the small sprocket SP11 (see, for example, FIG. Figure 3 In an upshift operation of a gear shift, the small sprocket SP11 is adjacent to the bicycle sprocket SP10 in an axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP10 without another sprocket therebetween. The upshift promoting section SP10G is intentionally designed to promote an upshift operation of shifting the bicycle chain 20 from the bicycle sprocket SP10 toward the small sprocket SP11.

[0139] The downshift facilitating section SP10H is configured to facilitate the bicycle chain 20 to shift from the second sprocket SP11 (see, for example, Figure 3 ) toward the first sprocket SP10. The downshift facilitating section SP10H is intentionally designed to facilitate a downshifting operation of the bicycle chain 20 from the second sprocket SP11 toward the first sprocket SP10. Therefore, the downshift facilitating section SP10H is configured to facilitate the bicycle chain 20 from the small sprocket SP11 (see, for example, Figure 3 The downshift promoting section SP10H is intentionally designed to promote a downshifting operation of the bicycle chain 20 from the small sprocket SP11 to the bicycle sprocket SP10.

[0140] The downshift facilitating section SP10H is positioned upstream of the upshift facilitating section SP10G in the circumferential direction D1. The downshift facilitating section SP10H is positioned upstream of the upshift facilitating section SP10G in the circumferential direction D1 relative to the rotational center axis A1 of the bicycle sprocket and in the driving rotational direction D11. The downshift facilitating section SP10H is positioned upstream of the upshift facilitating section SP10G in the driving rotational direction D11, and there is no other shift facilitating section between the upshift facilitating section SP10G and the downshift facilitating section SP10H.

[0141] The upshift facilitation section SP10G is formed by a first teeth group TG10A among the plurality of sprocket teeth SP10B. The downshift facilitation section SP10H is formed by a second teeth group TG10B among the plurality of sprocket teeth SP10B. The second teeth group TG10B is completely different from the first teeth group TG10A. The first teeth group TG10A of the upshift facilitation section SP10G and the second teeth group TG10B of the downshift facilitation section SP10H are adjacent to each other, with no teeth interposed therebetween.

[0142] The first teeth group TG10A includes upshift teeth SP10G1 and SP10G2 and upshift facilitating teeth SP10G3 and SP10G4. The second teeth group TG10B includes downshift facilitating teeth SP10H1 and SP10H2 and downshift teeth SP10H3 and SP10H4. The total number of sprocket teeth SP10B of the second teeth group TG10B is equal to the total number of sprocket teeth SP10B of the first teeth group TG10A. However, the total number of sprocket teeth SP10B of the second teeth group TG10B may differ from the total number of sprocket teeth SP10B of the first teeth group TG10A.

[0143] The total number of sprocket teeth SP10B provided from the downstream end of the downshift promotion section SP10H to the upstream end of the upshift promotion section SP10G in the reverse rotational direction D12 is greater than the total number of sprocket teeth SP10B provided from the downstream end of the downshift promotion section SP10H to the upstream end of the upshift promotion section SP10G in the drive rotational direction D11. In the present embodiment, the total number of sprocket teeth SP10B provided from the downstream end of the downshift promotion section SP10H to the upstream end of the upshift promotion section SP10G in the reverse rotational direction D12 is five. The total number of sprocket teeth SP10B provided from the downstream end of the downshift promotion section SP10H to the upstream end of the upshift promotion section SP10G in the drive rotational direction D11 is zero. However, the positional relationship between the upshift promotion section SP10G and the downshift promotion section SP10H is not limited to the present embodiment.

[0144] The upshift teeth SP10G2 are configured to engage with the outer chain spaces 20G of the opposing outer link plates 20A of the bicycle chain 20 (see, for example, FIG. 1 ). Figure 15), in an upshift operation, the opposing inner link plates 20B of the bicycle chain 20 are first derailed from the bicycle sprocket SP10.

[0145] The upshift tooth SP10G1 includes an upshift recess SP10G1R disposed on the sprocket-outward side SP10F to facilitate an upshift operation. The upshift recess SP10G1R is configured to derail the opposing outer link plates 20A of the bicycle chain 20 during an upshift operation if the upshift tooth SP10G2 derails the opposing inner link plates 20B of the bicycle chain 20 from the bicycle sprocket SP10.

[0146] The upshift tooth SP10G2 includes an upshift recess SP10G2R disposed on the sprocket outer side SP10F to facilitate an upshift operation. The upshift recess SP10G2R is configured to first derail the opposing inner link plates 20B of the bicycle chain 20 during an upshift operation.

[0147] like Figure 18 As shown, the upshift promoting tooth SP10G3 includes an upshift promoting recess SP10G3R provided on the inner side SP10E of the sprocket to promote upshifting. The upshift promoting recess SP10G3R is configured to promote the bicycle chain 20 to move toward the small sprocket SP11 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP10.

[0148] The upshift promoting tooth SP10G4 includes an upshift promoting recess SP10G4R disposed on the inner side SP10E of the sprocket to promote upshifting. The upshift promoting recess SP10G4R is configured to promote the bicycle chain 20 to move toward the small sprocket SP11 during an upshift operation when the bicycle chain 20 is engaged with the bicycle sprocket SP10.

[0149] like Figure 13 As shown, the downshift facilitating tooth SP10H1 includes a downshift facilitating recess SP10H1R disposed on the outer side SP10F of the sprocket to facilitate downshifting. The downshift facilitating recess SP10H1R is configured to reduce interference between the bicycle sprocket SP10 and the bicycle chain 20 during downshifting. The downshift facilitating recess SP10H1R is configured to facilitate movement of the bicycle chain 20 from the small sprocket SP11 toward the bicycle sprocket SP10 during downshifting, when the bicycle chain 20 is engaged with the small sprocket SP11.

[0150] The downshift facilitating tooth SP10H2 includes a downshift facilitating recess SP10H2R disposed on the sprocket's outer side SP10F to facilitate downshifting. The downshift facilitating recess SP10H2R is configured to reduce interference between the bicycle sprocket SP10 and the bicycle chain 20 during downshifting. The downshift facilitating recess SP10H2R is configured to facilitate movement of the bicycle chain 20 from the small sprocket SP11 toward the bicycle sprocket SP10 during downshifting, while the bicycle chain 20 is engaged with the small sprocket SP11.

[0151] The downshift teeth SP10H3 include a downshift recess SP10H3R disposed on the sprocket outer side SP10F to facilitate a downshift operation. The downshift recess SP10H3R is configured to facilitate engagement of the bicycle sprocket SP10 with the bicycle chain 20 during a downshift operation.

[0152] like Figure 18 As shown, the downshift tooth SP10H4 is configured to catch the opposing outer link plate 20A of the bicycle chain 20 during a downshift operation if one of the opposing inner link plates 20B contacts the downshift tooth SP10H3 during the downshift operation. The downshift tooth SP10H4 includes a downshift recess SP10H4R disposed on the sprocket inner side SP10E to facilitate the downshift operation. The downshift recess SP10H4R is configured to facilitate catching the opposing outer link plate 20A of the bicycle chain 20 at the downshift tooth SP10H4 during the downshift operation.

[0153] Figures 11 to 13 and Figures 16 to 18 The upshift facilitation sections SP8G, SP9G, and SP10G and the downshift facilitation sections SP8H, SP9H, and SP10H of the bicycle sprockets SP8, SP9, and SP10 shown in FIG. 1 can be applied to Figures 4 to 10 The bicycle sprockets SP1 to SP7 are shown in FIG.

[0154] like Figure 11 As shown, the plurality of sprocket teeth SP8B include at least one recessed tooth T8. In this embodiment, the plurality of sprocket teeth SP8B include recessed teeth T8. One of the recessed teeth T8 corresponds to the upshift tooth SP8G1 of the first tooth group TG8A. Another of the recessed teeth T8 corresponds to the upshift tooth SP8P1 of the third tooth group TG8C. The total number of recessed teeth T8 is not limited to this embodiment. The recessed teeth T8 have the same structure as one another. The recessed teeth may be any of the teeth SP8G2, SP8H1, SP8H2, SP8P2, SP9G1, SP9G2, SP9H1, SP9H2, SP10G1, SP1OG2, SP10H1, SP10H2, and the recessed teeth provided on the sprockets SP1 to SP7 and SP11.

[0155] like Figure 19As shown, at least one recessed tooth T8 has at least one recessed portion T8R. In the present embodiment, the recessed tooth T8 has one recessed portion T8R. However, if needed and / or desired, the recessed tooth T8 may have a plurality of recessed portions T8R.

[0156] At least one recessed portion T8R has a circumferential upstream end portion T8A and a circumferential downstream end portion T8B. Circumferential downstream end portion T8B is opposite to circumferential upstream end portion T8A in circumferential direction D1 relative to rotational center axis A1 and in driving rotational direction D11. Circumferential downstream end portion T8B is located downstream of circumferential upstream end portion T8A in driving rotational direction D11.

[0157] The recessed portion T8R includes a drive surface T8E and a non-drive surface T8F. The non-drive surface T8F is located on the opposite side of the drive surface T8E in the circumferential direction D1. The non-drive surface T8F is located downstream of the drive surface T8E in the driving rotational direction D11. The drive surface T8E is configured to receive the driving rotational force F1 from the bicycle chain 20 during pedaling. The drive surface T8E is located in the circumferential upstream end portion T8A. The non-drive surface T8F is located in the circumferential downstream end portion T8B.

[0158] like Figure 20 As shown, at least one recessed portion T8R is recessed from the sprocket outer side SP8F toward the sprocket inner side SP8E. The recessed portion T8R includes an upshift recessed portion SP8G1R. At least one recessed portion T8R has an inclined surface T8S. The inclined surface T8S extends between a circumferential upstream end T8A and a circumferential downstream end T8B. The inclined surface T8S is inclined relative to the rotational center axis. The inclined surface T8S is inclined relative to the circumferential direction D1.

[0159] The circumferential upstream end portion T8A has a first axial thickness AT81 defined at the pitch diameter PC81 of the bicycle sprocket SP8. The first axial thickness AT81 is defined in the axial direction D2. The circumferential downstream end portion T8B has a second axial thickness AT82 defined at the pitch diameter PC81 of the bicycle sprocket SP8. The second axial thickness AT82 is defined in the axial direction D2. The second axial thickness AT82 is smaller than the first axial thickness AT81. The first axial thickness AT81 is equal to or greater than 1.3 mm. The first axial thickness AT81 is preferably equal to or greater than 1.4 mm. In the present embodiment, the first axial thickness AT81 is equal to 1.5 mm. The second axial thickness AT82 is equal to 0.87 mm. However, the first axial thickness AT81 and the second axial thickness AT82 are not limited to the present embodiment.

[0160] In this embodiment, the inclined surface T8S does not have a stepped surface. Figure 21As shown, at least one recessed portion T8R may have at least one stepped surface T8C disposed between a circumferential upstream end portion T8A and a circumferential downstream end portion T8B. The at least one stepped surface T8C of the at least one recessed portion T8R may form at least three steps T8D. The at least one stepped surface T8C of the at least one recessed portion T8R may form three steps T8D.

[0161] like Figure 22 As shown, at least one of the plurality of sprocket teeth SP8B has an axial root thickness AT83 equal to or greater than 1.7 mm. The axial root thickness AT83 is defined as the tooth root SP8T of the sprocket tooth SP8B in the axial direction D2. The axial root thickness AT83 is greater than Figure 20 The first axial thickness AT81 and the second axial thickness AT82 are shown in FIG.

[0162] The first sprocket body SP8A has an axial thickness AT86 defined in the axial direction D2. The axial thickness AT86 is equal to or less than 2.0 mm. The axial thickness AT86 is equal to the axial tooth root thickness AT83. The range of each of the axial tooth root thickness AT83 and the axial thickness AT86 is from 1.7 mm to 2.0 mm. In the present embodiment, each of the axial tooth root thickness AT83 and the axial thickness AT86 is 1.95 mm. However, each of the axial tooth root thickness AT83 and the axial thickness AT86 is not limited to the present embodiment and the above-described ranges.

[0163] like Figure 23 As shown, the recessed tooth T8 has a first axial root thickness AT84 defined at the first root T8T1 of the recessed tooth T8. The first axial root thickness AT84 is less than the axial root thickness AT83.

[0164] like Figure 24 As shown, the recessed tooth T8 has a second axial root thickness AT85 defined at the second root T8T2 of the recessed tooth T8. The second axial root thickness AT85 is less than the axial root thickness AT83.

[0165] Figures 19 to 24 The structure of the bicycle sprocket SP8 shown in FIG. Figures 4 to 10 、 Figure 12 and Figure 13 The bicycle sprockets SP1 to SP7, SP9 and SP10 shown in FIG. Figure 4 As shown, the plurality of sprocket teeth SP1B include at least one recessed tooth T1. Figure 5 As shown, the plurality of sprocket teeth SP2B include at least one recessed tooth T2. Figure 6 As shown, the plurality of sprocket teeth SP3B include at least one recessed tooth T3. Figure 7As shown, the plurality of sprocket teeth SP4B include at least one recessed tooth T4. Figure 8 As shown, the plurality of sprocket teeth SP5B include at least one recessed tooth T5. Figure 9 As shown, the plurality of sprocket teeth SP6B include at least one recessed tooth T6. Figure 10 As shown, the plurality of sprocket teeth SP7B include at least one recessed tooth T7. Figure 12 As shown, the plurality of sprocket teeth SP9B include at least one recessed tooth T9. Figure 13 As shown, the plurality of sprocket teeth SP10B include at least one recessed tooth T10. The recessed teeth T1 to T7, T9, and T10 have substantially the same structure as the recessed tooth T8 of the bicycle sprocket SP8. Therefore, for the sake of brevity, they will not be described in detail here.

[0166] like Figure 25 As shown, a bicycle 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. The plurality of sprocket teeth SP11B are disposed on the outer periphery of the sprocket body SP11A. The plurality of sprocket teeth SP11B define a maximum tooth tip diameter DM11. The maximum tooth tip diameter DM11 is smaller than the maximum tooth tip diameter DM10 of the bicycle sprocket SP10.

[0167] like Figure 26 As shown, the bicycle sprocket SP11 includes an inboard sprocket side SP11E and an outboard sprocket side SP11F. The inboard sprocket side SP11E is configured to be closer to the axial center plane CP of the bicycle 2 than the outboard sprocket side SP11F when the bicycle sprocket SP11 is mounted on the bicycle 2. The outboard sprocket side SP11F is located on the opposite side of the inboard sprocket side SP11E in the axial direction D2 relative to the rotational center axis A1 of the bicycle sprocket SP11.

[0168] like Figure 27 and Figure 28 As shown, at least one of the plurality of sprocket teeth SP11B has a tooth tip SP11G, a tooth root SP11H, and at least one tooth tip chamfer SP11K and / or SP11L. The at least one tooth tip chamfer SP11K is formed on the tooth tip SP11G on at least one of the sprocket outer side SP11F and the sprocket inner side SP11E. The at least one tooth tip chamfer SP11K and / or SP11L has a radially outermost end SP11M and a radially innermost end SP11N relative to the rotational center axis A1 of the bicycle sprocket SP11.

[0169] In this embodiment, if Figure 25 As shown, the plurality of sprocket teeth SP11B include a plurality of chamfered teeth SP11S. Figure 27 and Figure 28As shown, each chamfered tooth SP11S has a tooth top SP11G, a tooth root SP11H, and at least one tooth top chamfer SP11K and / or SP11L. However, the total number of chamfered teeth SP11S is not limited to this embodiment.

[0170] like Figure 27 As shown, the tooth top chamfer SP11K is arranged on the outer side SP11F of the sprocket. The tooth top chamfer SP11K has a radially outermost end SP11M and a radially innermost end SP11N. Figure 28 As shown, the tooth top chamfer SP11L is provided on the inner side SP11E of the sprocket. The tooth top chamfer SP11L has a radially outermost end SP11M and a radially innermost end SP11N.

[0171] like Figure 27 and Figure 28 As shown, radial tooth tip distance RD11 is defined as the distance from tooth root SP11H to tooth tip SP11G in radial direction D4 relative to rotational center axis A1. Radial tooth tip distance RD11 is equal to or greater than 4.5 mm. Radial chamfer distance RD12 is defined as the distance from tooth root SP11H to the radially innermost end SP11N of at least one tooth tip chamfer SP11K in radial direction D4. Radial chamfer distance RD12 is equal to or greater than 3 mm.

[0172] In this embodiment, the radial tooth tip distance RD11 is 4.95 mm. The radial chamfer distance RD12 of the tooth tip chamfer SP11K is 3.45 mm. The radial chamfer distance RD12 of the tooth tip chamfer SP11L is 3.45 mm. However, the radial tooth tip distance RD11, the radial chamfer distance RD12 of the tooth tip chamfer SP11K, and the radial chamfer distance RD12 of the tooth tip chamfer SP11L are not limited to the present embodiment and the above ranges.

[0173] like Figure 27 As shown, the tooth tip SP11G has a circumferentially upstream tooth tip portion SP11G1 and a circumferentially downstream tooth tip portion SP11G2. The circumferentially downstream tooth tip portion SP11G2 is opposite to the circumferentially upstream tooth tip portion SP11G1 in the circumferential direction D1 relative to the rotational center axis A1 and in the drive rotational direction D11. The circumferentially downstream tooth tip portion SP11G2 is located downstream of the circumferentially upstream tooth tip portion SP11G1 in the drive rotational direction D11.

[0174] The circumferentially upstream tooth tip portion SP11G1 has a convexly curved portion SP11G3 configured to contact the chain roller 20R of the bicycle chain 20 during traveling operation of the bicycle 2. The convexly curved portion SP11G3 is configured to contact the chain roller 20R of the bicycle chain 20 during pedaling. The convexly curved portion SP11G3 has a curved profile when viewed along the rotational center axis A1. Figures 25 to 28 The structure of the bicycle sprocket SP11 shown in FIG. 1 can be applied to the bicycle sprockets SP1 to SP10 .

[0175] As used herein, the term "comprise" and its derivatives are intended to be open-ended terms that specify the presence of stated features, elements, components, groups, integers, and / or steps, but do not preclude the presence of other unstated features, elements, components, groups, integers, and / or steps. This concept also applies to words of similar meaning, for example, the terms "have," "include," and their derivatives.

[0176] 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 a plurality of parts.

[0177] Ordinal numbers such as "first" and "second" listed in this application are merely labels and do not have other meanings, such as a specific order, etc. In addition, 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".

[0178] The term "a pair" used herein may include a configuration in which a pair of elements have shapes or structures that are different from each other, in addition to a configuration in which a pair of elements have the same shape or structure as each other.

[0179] The terms "a" (or "an"), "one or more" and "at least one" are used interchangeably herein.

[0180] The phrase "at least one of which" as used in this disclosure means "one or more" of the desired options. For example, if the number of its options is two, the phrase "at least one of which" as used in this disclosure means "only a single option" or "both of the two options". For another example, if the number of its options is equal to or greater than three, the phrase "at least one of which" as used in this disclosure means "only one option" or "any combination of equal to or greater than two options". For example, the phrase "at least one of A and B" covers (1) A alone, (2) B alone, and (3) both A and B. The phrase "at least one of A, B, and C" covers (1) A alone, (2) B alone, (3) C alone, (4) both A and B, (5) both B and C, (6) both A and C, and (7) all of A, B, and C. In other words, in this disclosure, the phrase "at least one of A and B" does not mean "at least one of A and at least one of B".

[0181] Finally, as used herein, terms of degree such as "substantially," "approximately," and "approximately" mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. All numerical values ​​described in this application can be interpreted as including terms such as "substantially," "approximately," and "approximately."

[0182] Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings, and it is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.

Claims

1. A bicycle sprocket comprising: Sprocket body; The sprocket faces inboard; a sprocket outward side, the sprocket inward side being configured to be closer to an axial center plane of the bicycle than the sprocket outward side when the bicycle sprocket is mounted to the bicycle, the sprocket outward side being disposed on an opposite side of the sprocket inward side in an axial direction relative to a rotational center axis of the bicycle sprocket; and a plurality of sprocket teeth disposed on an outer circumference of the sprocket body, the plurality of sprocket teeth including at least one recessed tooth having at least one recessed portion recessed from an outer side of the sprocket toward an inner side of the sprocket, the at least one recessed portion having a circumferential upstream end and a circumferential downstream end opposite to the circumferential upstream end in a circumferential direction relative to the rotational center axis and relative to a driving rotational direction, the circumferential upstream end having a first axial thickness defined on a pitch circle of the bicycle sprocket, the circumferential downstream end having a second axial thickness defined on the pitch circle of the bicycle sprocket, the second axial thickness being smaller than the first axial thickness, the first axial thickness being equal to or greater than 1.3 mm.

2. The bicycle sprocket according to claim 1, wherein Each of the plurality of sprocket teeth is configured to enter each of an outer chain space defined between a pair of opposing outer link plates of a bicycle chain and an inner chain space defined between a pair of opposing inner link plates of the bicycle chain.

3. The bicycle sprocket according to claim 1, wherein The at least one recessed portion has an inclined surface extending between the circumferential upstream end and the circumferential downstream end.

4. The bicycle sprocket according to claim 1, wherein The at least one recessed portion has at least one stepped surface provided between the circumferential upstream end portion and the circumferential downstream end portion.

5. The bicycle sprocket according to claim 4, wherein The at least one stepped surface of the at least one concave portion forms at least three steps.

6. The bicycle sprocket according to claim 1 , further comprising: an upshift facilitating section configured to facilitate an upshifting operation of shifting a bicycle chain from the bicycle sprocket toward a small sprocket that is adjacent to the bicycle sprocket in the axial direction without another sprocket therebetween; and a downshift facilitation section configured to facilitate a downshift operation of shifting the bicycle chain from the small sprocket toward the bicycle sprocket, wherein The downshift promotion section is provided on an upstream side of the upshift promotion section in the circumferential direction.

7. The bicycle sprocket according to claim 6, wherein The upshift facilitation section is formed by a first set of teeth of the plurality of sprocket teeth, The downshift facilitation section is formed by a second set of teeth of the plurality of sprocket teeth, and The second set of teeth is completely different from the first set of teeth.

8. The bicycle sprocket according to claim 1, wherein At least one sprocket tooth of the plurality of sprocket teeth has an axial root thickness equal to or greater than 1.7 mm.

9. The bicycle sprocket according to claim 7, wherein The first set of teeth of the upshift facilitation section is adjacent to the second set of teeth of the downshift facilitation section without another tooth therebetween.

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