Rear sprocket for human-powered vehicle

Abstract

This invention provides a rear sprocket for a human-powered vehicle that improves strength and rigidity while achieving lightweight design. The rear sprocket (47) is used in a bicycle (1). The rear sprocket (47) has an outer ring (57), a plurality of sprocket teeth (59), an inner ring (61), and a connecting arm (63). The connecting arm (63) has a radially outer half (65) and a radially inner half (67). The second circumferential width (W2) of the radially inner half (67) is smaller than the first circumferential width (W1) of the radially outer half (65). The connecting arm (63) is tapered from a first radial position (RP1) toward a second radial position (RP2).

Description

Technical Field

[0001] This invention relates to a rear sprocket for a human-powered vehicle. Background Technology

[0002] The rear sprocket disclosed in Patent Document 1 has an outer ring body, multiple sprocket teeth, an inner ring body, and multiple connecting arms. The multiple sprocket teeth extend radially outward from the outer periphery of the outer ring body. In the assembled state where the rear sprocket is mounted on the hub assembly, the inner ring body is connected to the sprocket support.

[0003] Each of the multiple connecting arms extends radially between the outer and inner annular bodies. The circumferential width of each of the multiple connecting arms has a shape that decreases from the radially inner side to the radially outer side.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Chinese Patent Application Publication No. 102328724. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In existing rear sprockets, a rivet hole for connecting a rear sprocket to an adjacent rear sprocket is provided on the radially outer portion of the connecting arm. Therefore, when the circumferential width of the radially outer portion is small, the strength and rigidity around the rivet hole of the connecting arm are sometimes insufficient.

[0009] The purpose of this invention is to provide a rear sprocket for human-powered vehicles that can improve strength and rigidity and achieve lightweight design.

[0010] means for solving problems

[0011] Regarding a first aspect of the invention, a rear sprocket for a manually operated vehicle is used in a manually operated vehicle having an axial center plane. The rear sprocket for a manually operated vehicle has a rotation center axis, an axial outer surface, and an axial inner surface. The axial inner surface is located axially opposite to the axial outer surface about the rotation center axis. The axial inner surface is configured such that, in its mounted state on the manually operated vehicle, it is axially opposite to the axial center plane.

[0012] The rear sprocket for a manually driven vehicle has an outer ring, multiple sprocket teeth, an inner ring, and at least one connecting arm. The multiple sprocket teeth extend radially outward from the outer periphery of the outer ring about the axis of rotation. The inner ring is configured to connect to the sprocket support of the hub assembly when the rear sprocket is mounted on the hub assembly, so as to transmit torque.

[0013] At least one connecting arm extends radially between the outer annulus and the inner annulus. The at least one connecting arm has a radially outer half and a radially inner half. The radially inner half is located radially from the radially outer half towards the radially inner side.

[0014] Each of the multiple sprocket teeth has a maximum radial length and a maximum axial length. The maximum radial length is defined radially. The maximum axial length is defined axially. The maximum axial length is shorter than the maximum radial length.

[0015] The outer radial half has a first circumferential width. This first circumferential width is defined by a first radial position about the axis of rotation. The inner radial half has a second circumferential width. This second circumferential width is defined by a second radial position about the axis of rotation. The second circumferential width is smaller than the first circumferential width.

[0016] At least one connecting arm is formed in a tapered shape from a first radial position toward a second radial position. The outer annular body, multiple sprocket teeth, inner annular body, and at least one connecting arm are formed as a single integral component.

[0017] In the rear sprocket for a manually operated vehicle according to the first aspect, since the second circumferential width of the radially inner half is smaller than the first circumferential width of the radially outer half, the rear sprocket can be lightweight in the radially inner half. Furthermore, since the first circumferential width of the radially outer half is larger than the second circumferential width of the radially inner half, the strength and rigidity of the radially outer half can be improved. In other words, the rear sprocket for a manually operated vehicle achieves both improved strength and rigidity while also being lightweight.

[0018] Regarding a second aspect of the invention, the rear sprocket of the human-powered vehicle according to the first aspect is configured such that at least one connecting arm includes a plurality of connecting arms.

[0019] In the second aspect, for the rear sprocket of a human-powered vehicle, in each of the multiple connecting arms, the second circumferential width of the radially inner half is smaller than the first circumferential width of the radially outer half. According to this structure, the strength and rigidity of the radially outer half can be improved, while weight reduction can be achieved in the radially inner half.

[0020] Regarding the third aspect of the invention, the rear sprocket of the human-powered vehicle according to the second aspect is configured such that the total number of multiple connecting arms is 4 or more.

[0021] In the third aspect, for the rear sprocket of a human-powered vehicle, the strength and rigidity of the radially outer half can be appropriately improved, while the weight reduction of the radially inner half can be appropriately achieved.

[0022] Regarding a fourth aspect of the invention, the rear sprocket of a manually driven vehicle according to any one of the first to third aspects is configured such that at least one connecting arm has a rivet hole. The rivet hole is located at a first radial position within a first circumferential width.

[0023] In the fourth aspect of the rear sprocket for a human-powered vehicle, since the rivet hole is located at the first radial position of the first circumferential width, the required strength and rigidity around the rivet hole can be ensured even if the rivet hole is located in the radially outer half. Furthermore, by fixing the rear sprocket to the adjacent rear sprocket through the rivet hole in the radially outer half, the axial strength and rigidity of the rear sprocket assembly can be improved.

[0024] Regarding the fifth aspect of the invention, the rear sprocket of the manually driven vehicle according to the fourth aspect is configured as follows: The rivet hole has a diameter. The ratio of the first circumferential width to the hole diameter is 2.5 or more.

[0025] In the fifth aspect, for the rear sprocket of a human-powered vehicle, even if the rivet hole is located in the radially outer half, the required strength and rigidity around the rivet hole can be ensured by setting the ratio of the first circumferential width to the hole diameter to be 2.5 or more.

[0026] Regarding the sixth aspect of the invention, the rear sprocket of a manually driven vehicle according to any one of the first to fifth aspects is configured as follows: The inner annular body has a spline portion. The spline portion is configured to engage with a sprocket support body of the hub assembly in the assembled state.

[0027] In the sixth aspect, the rear sprocket for a human-powered vehicle can reliably transmit the driving torque from the rear sprocket to the hub assembly via the spline of the inner annular body.

[0028] Regarding the seventh aspect of the present invention, the rear sprocket of the human-powered vehicle according to any one of the first to sixth aspects is configured such that the first circumferential width is 11 mm or more.

[0029] In the seventh aspect, the rear sprocket for human-powered vehicles, by setting the first circumferential width to 11 mm or more, can appropriately improve the strength and rigidity of the radially outer half.

[0030] Regarding the eighth aspect of the present invention, the rear sprocket of the human-powered vehicle according to any one of the first to seventh aspects is configured such that the first circumferential width is 20 mm or less.

[0031] In the eighth aspect, for the rear sprocket of a human-powered vehicle, by setting the first circumferential width to less than 20 mm, it is possible to suppress the increase in weight of the radially outer half.

[0032] Regarding the ninth aspect of the present invention, the rear sprocket of the human-powered vehicle according to any one of the first to eighth aspects is configured such that the second circumferential width is 5 mm or more.

[0033] In the rear sprocket for human-powered vehicles in the ninth aspect, by setting the second circumferential width to 5mm or more, the strength and rigidity of the radial inner half can be ensured.

[0034] Regarding the tenth aspect of the present invention, the rear sprocket of the human-powered vehicle according to any one of the first to ninth aspects is configured such that the second circumferential width is 10 mm or less.

[0035] In the tenth aspect, the rear sprocket for human-powered vehicles, by setting the second circumferential width to less than 10 mm, can be appropriately lightweighted in the radially inner half.

[0036] Regarding the eleventh aspect of the present invention, the rear sprocket of the manually driven vehicle according to any one of the first to tenth aspects is configured as follows: A plurality of sprocket teeth include a plurality of downshift actuating teeth. The plurality of downshift actuating teeth are configured to actuate a downshifting action by moving the drive chain from a small sprocket adjacent to the rear sprocket to the rear sprocket.

[0037] The multiple downshift actuating teeth include a downshift initiation tooth and a downshift recessed tooth. The downshift initiation tooth is configured to engage with the drive chain first during the downshifting action. The downshift recessed tooth is located downstream of the downshift initiation tooth in the drive rotation direction with respect to the rear sprocket and is positioned adjacent to the downshift initiation tooth.

[0038] In the circumferential direction about the rotation center axis, no other sprocket teeth are arranged between the downshift initiation tooth and the downshift recess tooth. The downshift recess tooth has a downshift recess. The downshift recess is provided on the axially outer side of the downshift recess tooth in such a way that it is recessed from the axially outer side to the axially inner side.

[0039] In the rear sprocket of the human-powered vehicle in the eleventh aspect, since multiple sprocket teeth include the aforementioned multiple downshifting actuation teeth, the impact during downshifting can be mitigated and the downshifting action can be performed smoothly.

[0040] Regarding the twelfth aspect of the present invention, the rear sprocket of the manually driven vehicle according to the eleventh aspect is configured as follows: A first axial recess is provided on the axial inner side of the downshift initiation tooth, such that it is recessed axially from the axial inner side to the axial outer side. The first axial recess is disposed at least at the tooth tip of the downshift initiation tooth.

[0041] In the twelfth aspect of the rear sprocket for a human-powered vehicle, since the first axial recess is provided on the axial inner side of the downshift initiation tooth, the impact during downshifting can be appropriately mitigated and the downshifting action can be performed more smoothly.

[0042] Regarding the thirteenth aspect of the present invention, the rear sprocket of the manually driven vehicle according to the eleventh or twelfth aspect is configured as follows: The downshift recess has a first downshift recess and a second downshift recess. The first downshift recess and the second downshift recess are respectively provided on the axially outer side of the downshift recess teeth in such a way that they are recessed from the axially outer side to the axially inner side.

[0043] The first recess for downshifting has a first recess bottom surface. The second recess for downshifting has a second recess bottom surface. A first axial depth is defined axially from the axially outer side of the outer annulus to the bottom surface of the first recess. A second axial depth is defined axially from the axially outer side of the outer annulus to the bottom surface of the second recess. The first axial depth is smaller than the second axial depth.

[0044] In the rear sprocket for a human-powered vehicle in the thirteenth aspect, since the downshift recess has a first downshift recess and a second downshift recess, the impact during downshifting can be appropriately mitigated and the downshifting action can be performed more smoothly.

[0045] Regarding the fourteenth aspect of the invention, the rear sprocket of the manually driven vehicle according to the thirteenth aspect is configured as follows: The downshift recess tooth has a first tooth tip. The downshift first recess reaches the first tooth tip of the downshift recess tooth.

[0046] In the fourteenth aspect of the rear sprocket for a human-powered vehicle, since the first downshift recess reaches the first tooth tip of the downshift recess tooth, the impact during downshifting can be appropriately mitigated and the downshifting action can be performed more smoothly.

[0047] Regarding the fifteenth aspect of the invention, the rear sprocket of the manually driven vehicle according to the thirteenth or fourteenth aspect is configured as follows: The downshift recess tooth has a driving surface and a non-driving surface, the non-driving surface being disposed circumferentially opposite to the driving surface. The first downshift recess reaches the driving surface of the downshift recess tooth.

[0048] In the rear sprocket for a human-powered vehicle in the fifteenth aspect, since the first downshift recess reaches the drive surface of the downshift recess teeth, the impact during downshifting can be appropriately mitigated and the downshifting action can be performed more smoothly.

[0049] Regarding the sixteenth aspect of the present invention, the rear sprocket of the human-powered vehicle according to the fifteenth aspect is configured such that the second downshift recess does not reach the drive surface of the downshift recess teeth.

[0050] In the rear sprocket for a human-powered vehicle in the sixteenth aspect, since the second downshift recess does not reach the drive surface of the downshift recess teeth, the impact during downshifting can be appropriately mitigated and the downshifting action can be performed more smoothly.

[0051] Regarding the seventeenth aspect of the present invention, the rear sprocket of the human-powered vehicle according to any one of the thirteenth to sixteenth aspects is configured such that no other recess is provided between the downshift first recess and the downshift second recess, and the downshift first recess and the downshift second recess are arranged adjacent to each other.

[0052] In the seventeenth aspect of the rear sprocket for a human-powered vehicle, since the first downshift recess and the second downshift recess are arranged adjacent to each other, the impact during downshifting can be appropriately mitigated and the downshifting action can be performed more smoothly.

[0053] Regarding the eighteenth aspect of the invention, the rear sprocket of a manually driven vehicle according to any one of the first to seventeenth aspects is configured as follows: A plurality of sprocket teeth include a plurality of upshift actuating teeth. The plurality of upshift actuating teeth are configured to actuate an upshifting action. The upshifting action is the action of driving the chain to move from the rear sprocket to a small sprocket adjacent to the rear sprocket.

[0054] In the rear sprocket for a human-powered vehicle in the eighteenth aspect, since multiple sprocket teeth include multiple upshift facilitating teeth, the impact during upshifting can be mitigated and the upshifting action can be performed smoothly.

[0055] Regarding the nineteenth aspect of the present invention, the rear sprocket of the manually driven vehicle according to the eighteenth aspect is configured as follows: A plurality of upshift actuating teeth include upshift displacement teeth, upshift initiation teeth, and upshift recess teeth. The upshift displacement teeth are configured to displace the drive chain toward the small sprocket during upshifting. The upshift initiation teeth are configured to be the first to disengage from the drive chain during upshifting.

[0056] The upshift initiation tooth has an upshift first recess. This first recess is provided on the axially outer side of the upshift initiation tooth, recessed axially from the axially outer side to the axially inner side. In the circumferential direction about the rotation center axis, no other sprocket teeth are arranged between the upshift initiation tooth and the upshift displacement tooth, and the upshift initiation tooth is positioned adjacent to the upshift displacement tooth on the upstream side of the upshift displacement tooth in the drive rotation direction about the rear sprocket.

[0057] The upshift recess tooth has a second upshift recess. The second upshift recess is provided on the axially outer side of the upshift recess tooth in such a way that it is recessed from the axially outer side to the axially inner side. In the circumferential direction, no other sprocket teeth are arranged between the upshift recess tooth and the upshift initiation tooth, and the upshift recess tooth is arranged adjacent to the upshift initiation tooth on the upstream side with respect to the drive rotation direction.

[0058] In the rear sprocket for a human-powered vehicle in the nineteenth aspect, since multiple upshifting actuation teeth, including upshifting displacement teeth, upshifting initiation teeth, and upshifting recess teeth, can appropriately mitigate the impact during upshifting and enable smoother upshifting.

[0059] Regarding the twentieth aspect of the present invention, the rear sprocket of the manually driven vehicle according to the nineteenth aspect is configured as follows: A second axial recess is provided on the axial inner side of the upshift displacement tooth, such that it is recessed axially from the axial inner side to the axial outer side. The second axial recess is disposed at least at the tooth tip of the upshift displacement tooth.

[0060] In the twentieth aspect of the rear sprocket for a human-powered vehicle, since the second axial recess is provided on the axial inner side of the upshift displacement tooth, the impact during upshifting can be appropriately mitigated and the upshifting action can be performed more smoothly.

[0061] Invention Effects

[0062] According to the present invention, the strength and rigidity of the rear sprocket for human-powered vehicles can be improved, and the weight reduction of the rear sprocket for human-powered vehicles can be achieved. Attached Figure Description

[0063] Figure 1 This is a side view of a bicycle according to an embodiment of the present invention;

[0064] Figure 2 This is a diagram showing the bicycle as viewed from above.

[0065] Figure 3 This is a 3D view of the rear sprocket assembly;

[0066] Figure 4 This is a cross-sectional view of the rear sprocket assembly;

[0067] Figure 5 It is a 3D diagram of the seventh and eighth sprockets;

[0068] Figure 6A This is a front view of the seventh sprocket;

[0069] Figure 6B This is a view of the back of the seventh sprocket;

[0070] Figure 6C This is a partially enlarged sectional view of the tooth tips in the seventh and eighth sprockets;

[0071] Figure 7A This is a front view of the seventh sprocket used to illustrate the gear shifting action;

[0072] Figure 7B This is a back view of the seventh sprocket used to illustrate the shifting action;

[0073] Figure 8A This is a front view of the eighth sprocket;

[0074] Figure 8B This is a view of the back of the eighth sprocket;

[0075] Figure 9A This is a front view of the eighth sprocket used to illustrate the gear shifting action;

[0076] Figure 9B This is a back view of the eighth sprocket used to illustrate the shifting action. Detailed Implementation

[0077] like Figure 1 As shown, the bicycle 1 according to an embodiment of the present invention includes a drive chain 3, a frame 5, handlebars 7, a front wheel 9, a rear wheel 11, a gear shifting mechanism 13, a drive unit 15, and a front fork 17. The bicycle 1 also includes a front derailleur 21 and a rear derailleur 23. The bicycle 1 is an example of a human-powered vehicle according to the present invention. Figure 2 As shown, bicycle 1 has an axial center plane P.

[0078] like Figure 1 As shown, the front fork 17 is rotatably mounted to the frame 5. The handlebars 7 are fixed to the front fork 17. The front wheel 9 is rotatably mounted to the front fork 17 via the front hub assembly 18. The rear wheel 11 is rotatably mounted to the rear of the frame 5 via the rear hub assembly 19. The front tire 9a is mounted to the front wheel 9. The rear tire 11a is mounted to the rear wheel 11.

[0079] The shifting mechanism 13 is mounted on the handlebars 7. The shifting mechanism 13 actuates the front derailleur 21 and the rear derailleur 23 via cables. For example, the rear derailleur 23 is mounted on the frame 5. The rear derailleur 23 moves the drive chain 3 from one rear sprocket to the other rear sprockets via the shifting mechanism 13.

[0080] The front derailleur 21 is mounted on the frame 5. The front derailleur 21 moves the drive chain 3 from one front sprocket to another via the shifting mechanism 13. That is, the operation of the shifting mechanism 13 actuates the front derailleur 21, thereby performing upshifting and downshifting actions.

[0081] The drive unit 15 mainly includes a rear hub assembly 19, a rear sprocket assembly 27, and a crank assembly 29. The drive unit 15 may include a drive chain 3. The rear hub assembly 19 is mounted on the frame 5.

[0082] The rear hub assembly 19 is connected to the rear wheel 11. The rear hub assembly 19 rotates integrally with the rear wheel 11. The rear hub assembly 19 rotates relative to the frame 5 via a hub axle (not shown). The rear hub assembly 19 is configured to rotate together with the rear sprocket assembly 27.

[0083] like Figure 1 and Figure 2As shown, the rear sprocket assembly 27 has a rotational center axis X. The rear sprocket assembly 27 rotates about the rotational center axis X. For example, the rear sprocket assembly 27 is rotatably supported on the rear hub assembly 19. The driving force input from the rider of the bicycle 1 to the crank assembly 29 is transmitted to the rear sprocket assembly 27 via the drive chain 3. Details of the rear sprocket assembly 27 will be described later.

[0084] like Figure 1 As shown, the crank assembly 29 has a crank arm 31 and a front sprocket assembly 33. The crank arm 31 is rotatably supported on the lower part of the frame 5. The front sprocket assembly 33 is mounted on the crank arm 31 in a manner that allows it to rotate integrally with the crank arm 31. The front sprocket assembly 33 has at least one front sprocket.

[0085] like Figure 3 As shown, the rear sprocket assembly 27 has multiple rear sprockets 41-51. These multiple rear sprockets 41-51 are used in the bicycle 1. Each of the multiple rear sprockets 41-51 engages with the drive chain 3. The driving force transmitted from the crank assembly 29 to the drive chain 3 is transmitted to each of the multiple rear sprockets 41-51.

[0086] like Figure 4 As shown, each of the plurality of rear sprockets 41 to 51 is mounted on the sprocket support 19a of the rear hub assembly 19 in such a way that it rotates integrally with the sprocket support 19a of the rear hub assembly 19.

[0087] In this embodiment, an example is shown where the plurality of rear sprockets 41 to 51 include 11 rear sprockets. The first rear sprockets 41 to the eleventh rear sprockets 51 are arranged coaxially about the rotational axis X. The first rear sprockets 41 to the eleventh rear sprockets 51 are arranged axially about the rotational axis X. In the third rear sprockets 43 to the ninth rear sprockets 49, spacers 28a to 28f are arranged between adjacent sprockets.

[0088] The seventh to ninth rear sprockets 47 are connected to each other by the first rivet 53a. The eighth to tenth rear sprockets 50 are connected to each other by the second rivet 53b. The ninth and tenth rear sprockets 49 are connected to each other by the third rivet 53c. The tenth and eleventh rear sprockets 50 are connected to each other by the fourth rivet 53d. The first to eleventh rear sprockets 41 and the washers 28a to 28f are connected to each other by the connecting part 53e.

[0089] In this embodiment, the seventh rear sprocket 47 and the eighth rear sprocket 48 have the characteristic structure of the present invention. Hereinafter, the seventh rear sprocket 47 and the eighth rear sprocket 48 will be described in detail.

[0090] ·Seventh rear sprocket

[0091] like Figure 5 , Figure 6A and Figure 6B As shown, the seventh rear sprocket 47 has a rotation center axis X, a first axial outer surface 47a, and a first axial inner surface 47b. The rotation center axis X is concentric with the rotation center axis of the aforementioned rear sprocket assembly 27. Figure 5 and Figure 6A As shown, the first axial outer surface 47a forms the outer surface of the seventh rear sprocket 47 in the axial direction about the rotation center axis X.

[0092] like Figure 5 and Figure 6B As shown, the first axial inner surface 47b forms the inner surface of the seventh rear sprocket 47 in the axial direction about the rotation center axis X. The first axial inner surface 47b is located on the opposite side of the first axial outer surface 47a in the axial direction about the rotation center axis X. The first axial inner surface 47b is configured such that, in the mounted state on the bicycle 1, in the axial direction about the rotation center axis X, it is adjacent to... Figure 2 The axial center plane P shown is positioned relative to each other.

[0093] like Figure 6A and Figure 6B As shown, the seventh rear sprocket 47 includes a first outer ring 57, a plurality of first sprocket teeth 59, a first inner ring 61, and at least one first connecting arm 63. The first outer ring 57, the plurality of first sprocket teeth 59, the first inner ring 61, and at least one first connecting arm 63 are formed as a single integral component.

[0094] A plurality of first sprocket teeth 59 extend radially outward from the outer periphery 57a of the first outer annular body 57 about the rotation center axis X. In this embodiment, the total number of teeth of the plurality of first sprocket teeth 59 is 26.

[0095] like Figure 6C As shown, each of the plurality of first sprocket teeth 59 has a first maximum radial length L1 and a first maximum axial length L2. The first maximum radial length L1 is defined radially about the axis of rotation X. For example, the first maximum radial length L1 is the length in the radial direction about the axis of rotation X, from the outer periphery 57a of the first outer annulus 57 to the tooth tip 59a of the plurality of first sprocket teeth 59. The outer periphery 57a of the first outer annulus 57 is defined by the tooth root circle 57b of the plurality of first sprocket teeth 59.

[0096] The first maximum axial length L2 is defined in the axial direction about the rotation center axis X. For example, the first maximum axial length L2 is the maximum length between the first axial outer surface 47a and the first axial inner surface 47b of the plurality of first sprocket teeth 59 in the axial direction about the rotation center axis X.

[0097] The first maximum axial length L2 is the maximum length between the first axial outer surface 47a and the first axial inner surface 47b at the position of the outer periphery 57a of the first outer annular body 57. The first maximum axial length L2 is shorter than the first maximum radial length L1.

[0098] like Figure 4 As shown, the first inner ring 61 is configured to connect to the sprocket support 19a of the rear hub assembly 19 when the seventh rear sprocket 47 is mounted on the rear hub assembly 19, so as to transmit torque.

[0099] like Figure 5 , Figure 6A and Figure 6B As shown, the first inner annular body 61 has a first spline hole 61a. The first spline hole 61a forms the inner circumferential surface of the first inner annular body 61. Figure 4 As shown, the first spline hole 61a is configured to engage with the sprocket support 19a of the rear hub assembly 19 when the seventh rear sprocket 47 is mounted on the rear hub assembly 19. For example, the sprocket support 19a is a cylindrical spline shaft.

[0100] like Figure 5 , Figure 6A and Figure 6B As shown, at least one first connecting arm 63 extends radially about the rotation center axis X between the first outer annulus 57 and the first inner annulus 61.

[0101] like Figure 6A and Figure 6B As shown, at least one first connecting arm 63 is formed in a tapered shape from a first radial position RP1 toward a second radial position RP2. For example, at least one first connecting arm 63 is formed in a tapered shape such that the first circumferential width W1 of the first connecting arm 63 gradually decreases as it moves from the first radial position RP1 toward the second radial position RP2. Details of the first circumferential width W1 will be described later.

[0102] like Figure 6A and Figure 6B As shown, at least one first connecting arm 63 has a first radially outer half 65 and a first radially inner half 67. At least one first connecting arm 63 has a first rivet hole 69. The first rivet hole 69 provides... Figure 4 The first rivet 53a shown is inserted.

[0103] At least one first connecting arm 63 includes a plurality of first connecting arms 63. Preferably, the total number of the plurality of first connecting arms 63 is 4 or more. In this embodiment, the total number of the plurality of first connecting arms 63 is 7.

[0104] like Figure 6A and Figure 6B As shown, the first radially outer half 65 is disposed radially between the first outer annular body 57 and the first radially inner half 67 about the rotation center axis X. The first radially outer half 65 is integrally formed with the first outer annular body 57 and the first radially inner half 67.

[0105] The first radially outer half 65 has a first circumferential width W1. The first circumferential width W1 is defined by a first radial position RP1 about the axis of rotation X. The first circumferential width W1 is the length of an arc extending circumferentially about the axis of rotation X at the first radial position RP1. For example, the first circumferential width W1 is 11 mm or more. The first circumferential width W1 is 20 mm or less. That is, the first circumferential width W1 is 11 mm or more and 20 mm or less.

[0106] like Figure 6A and Figure 6B As shown, the first radially inner half 67 is located radially inward from the first radially outer half 65 about the rotation center axis X. The first radially inner half 67 is disposed between the first radially outer half 65 and the first inner annular body 61 about the rotation center axis X. The first radially inner half 67, the first radially outer half 65, and the first inner annular body 61 are integrally formed.

[0107] The first radial inner half 67 has a second circumferential width W2. The second circumferential width W2 is defined by a second radial position RP2 about the axis of rotation X. The second circumferential width W2 is the length of the arc extending circumferentially about the axis of rotation X at the second radial position RP2.

[0108] For example, the second circumferential width W2 is smaller than the first circumferential width W1. The second circumferential width W2 is 5mm or more. The second circumferential width W2 is 10mm or less. That is, the second circumferential width W2 is 5mm or more and 10mm or less.

[0109] like Figure 6A and Figure 6B As shown, a first rivet hole 69 is provided at a first radial position RP1 of a first circumferential width W1. The first rivet hole 69 has a hole diameter D1. For example, the ratio of the first circumferential width W1 to the hole diameter D1, W1 / D1, is 2.5 or more. The ratio of the first circumferential width W1 to the hole diameter D1, W1 / D1, is 5.0 or less.

[0110] That is, the ratio of the first circumferential width W1 to the aperture D1, W1 / D1, is 2.5 or more and 5.0 or less. In this embodiment, the first circumferential width W1 is 13.8 mm and the aperture D1 is 4.73 mm. In this case, the ratio of the first circumferential width W1 to the aperture D1, W1 / D1, is approximately 2.9.

[0111] The aforementioned seventh rear sprocket 47 is configured as follows to smoothly facilitate downshifting. For example... Figure 7A and Figure 7B As shown, the plurality of first sprocket teeth 59 include a plurality of downshifting actuating teeth 59D1 and 59D2. The plurality of first sprocket teeth 59 may also include an additional downshifting actuating tooth 59D3. The plurality of downshifting actuating teeth 59D1, 59D2, and the additional downshifting actuating tooth 59D3 constitute a mechanism for actuating a downshifting action. The downshifting action is the action of driving the chain 3 to move from the sixth rear sprocket 46 adjacent to the seventh rear sprocket 47 to the seventh rear sprocket 47. That is, in this embodiment, the downshifting action is the action of driving the chain 3 to move from the small sprocket 46 adjacent to the rear sprocket 47 to the rear sprocket 47.

[0112] Multiple downshifting actuating teeth 59D1 and 59D2 include a downshift initiation tooth 59D1 and a downshifting recessed tooth 59D2. An additional downshifting actuating tooth 59D3 includes an additional downshifting recessed tooth 59D3. The downshift initiation tooth 59D1 is configured to engage with the drive chain 3 first during the downshifting operation.

[0113] For example, during downshifting, when the outer link of the drive chain 3 is in the position of the additional downshifting facilitator tooth 59D3 and the inner link of the drive chain 3 is in the position of the downshifting facilitator tooth 59D2, the outer link of the drive chain 3 engages with the downshifting initiation tooth 59D1 first.

[0114] The downshift initiation tooth 59D1 is located on the upstream side of the drive rotation direction RD of the seventh rear sprocket 47, among multiple downshift promoting teeth 59D1, 59D2, and additional downshift promoting tooth 59D3.

[0115] like Figure 7A As shown, the downshift initiation tooth 59D1 has a driving surface 59D1a and a non-driving surface 59D1b. The driving surface 59D1a is located upstream of the seventh rear sprocket 47 in the driving rotation direction RD. The non-driving surface 59D1b is located on the opposite side of the driving surface 59D1a in the circumferential direction about the rotation center axis X. The axially outer surface of the tooth tip 59D1c is inclined such that the tooth tip 59D1c on the driving surface 59D1a side is positioned further axially inward than the tooth tip 59D1d on the non-driving surface 59D1b side.

[0116] like Figure 7BAs shown, the downshift initiation tooth 59D1 has a first axial recess 59D1e. The first axial recess 59D1e is provided on the first axial inner surface 47b of the downshift initiation tooth 59D1. For example, the first axial recess 59D1e is provided on the first axial inner surface 47b of the downshift initiation tooth 59D1 in such a way that it is recessed from the first axial inner surface 47b to the first axial outer surface 47a in the axial direction about the rotation center axis X. The first axial recess 59D1e is disposed at least on the tooth tip 59D1f of the downshift initiation tooth 59D1.

[0117] The first axial recess 59D1e can be a recess or an inclined portion. The first axial recess 59D1e can extend radially inward from the tooth tip 59D1c of the downshift starting tooth 59D1 about the rotation center axis X.

[0118] like Figure 7A As shown, the downshift recessed tooth 59D2 is arranged adjacent to the downshift initiation tooth 59D1 on the downstream side of the downshift initiation tooth 59D1 in the drive rotation direction RD with respect to the seventh rear sprocket 47. In the circumferential direction with respect to the rotation center axis X, no other first sprocket teeth 59 are arranged between the downshift initiation tooth 59D1 and the downshift recessed tooth 59D2.

[0119] like Figure 7A As shown, the downshift recess tooth 59D2 has a driving surface 59D2a and a non-driving surface 59D2b. The driving surface 59D2a is located upstream of the driving rotation direction RD of the seventh rear sprocket 47 relative to the non-driving surface 59D2b. The non-driving surface 59D2b is located on the opposite side of the driving surface 59D2a in the circumferential direction about the rotation center axis X.

[0120] like Figure 7A As shown, the downshift recessed tooth 59D2 has a first tooth tip 59D2c. The downshift recessed tooth 59D2 has a downshift recess 71D2. The downshift recess 71D2 is provided on the first axial outer surface 47a of the downshift recessed tooth 59D2. For example, the downshift recess 71D2 is provided on the first axial outer surface 47a of the downshift recessed tooth 59D2 in an axial direction about the rotation center axis X, in a manner that it is recessed from the first axial outer surface 47a to the first axial inner surface 47b.

[0121] In detail, the downshift recess 71D2 has a first downshift recess 71D2a and a second downshift recess 71D2b. Each of the first downshift recess 71D2a and the second downshift recess 71D2b is provided on the first axial outer surface 47a of the downshift recess tooth 59D2 in an axial direction about the rotation center axis X, in a manner that it is recessed from the first axial outer surface 47a to the first axial inner surface 47b.

[0122] like Figure 7AAs shown, the first downshift recess 71D2a and the second downshift recess 71D2b are arranged circumferentially about the rotation center axis X. No other recesses are arranged between the first downshift recess 71D2a and the second downshift recess 71D2b, and the first downshift recess 71D2a and the second downshift recess 71D2b are arranged adjacent to each other.

[0123] The first recess 71D2a of the downshift reaches the first tooth tip 59D2c of the downshift recess tooth 59D2. The first recess 71D2a of the downshift reaches the driving surface 59D2a of the downshift recess tooth 59D2.

[0124] like Figure 7A As shown, the first recess 71D2a has a first recess bottom surface 71D2c. ​​The first axial depth is defined as the distance along the axial direction about the rotation center axis X, from the first axially outer surface 47a of the first outer annulus 57 to the first recess bottom surface 71D2c. ​​For example, the first axial depth along the axial direction about the rotation center axis X is defined by the maximum distance from the first axially outer surface 47a of the first outer annulus 57 to the first recess bottom surface 71D2c.

[0125] like Figure 7A As shown, the second downshift recess 71D2b does not reach the drive surface 59D2a of the downshift recess tooth 59D2. The second downshift recess 71D2b has a second recess bottom surface 71D2d. The second axial depth is defined as the distance from the first axially outer surface 47a of the first outer annulus 57 to the bottom surface 71D2d of the second recess in the axial direction about the rotation center axis X. For example, the second axial depth in the axial direction about the rotation center axis X is defined by the maximum distance from the first axially outer surface 47a of the first outer annulus 57 to the bottom surface 71D2d of the second recess. The first axial depth is smaller than the second axial depth.

[0126] The additional downshift recessed tooth 59D3 is arranged adjacent to the downshift recessed tooth 59D2 on the downstream side of the downshift recessed tooth 59D2 in the drive rotation direction RD of the seventh rear sprocket 47. In this embodiment, the downshift recessed tooth 59D2 and the additional downshift recessed tooth 59D3 are arranged in the drive rotation direction RD of the seventh rear sprocket 47.

[0127] The additional downshift recessed tooth 59D3 has a driving surface 59D3a and a non-driving surface 59D3b. The driving surface 59D3a is located upstream of the driving rotation direction RD of the seventh rear sprocket 47 relative to the non-driving surface 59D3b. The non-driving surface 59D3b is located on the opposite side of the driving surface 59D3a in the circumferential direction about the rotation center axis X.

[0128] like Figure 7AAs shown, the additional downshift recessed tooth 59D3 has a second tooth tip 59D3c. The additional downshift recessed tooth 59D3 has an additional downshift recess 71D3. The additional downshift recess 71D3 is provided on the first axial outer surface 47a of the additional downshift recessed tooth 59D3. For example, the additional downshift recess 71D3 is provided on the first axial outer surface 47a of the additional downshift recessed tooth 59D3 in such a way that it is recessed from the first axial outer surface 47a to the first axial inner surface 47b in the axial direction about the rotation center axis X.

[0129] The additional downshift recess 71D3 reaches the second tooth tip 59D3c of the additional downshift recess tooth 59D3. The additional downshift recess 71D3 reaches the driving surface 59D3a and the non-driving surface 59D3b of the additional downshift recess tooth 59D3.

[0130] The aforementioned seventh rear sprocket 47 is configured as follows to smoothly facilitate upshifting. For example... Figure 7A and Figure 7B As shown, the plurality of first sprocket teeth 59 include a plurality of upshift promoting teeth 59U1, 59U2, and 59U3. The plurality of first sprocket teeth 59 may include an additional upshift promoting tooth 59U0.

[0131] Multiple upshifting actuating teeth 59U1, 59U2, and 59U3 constitute an upshifting actuation. An additional upshifting actuating tooth 59U0 constitutes an upshifting actuation. The upshifting actuation is the movement of the drive chain 3 from the seventh rear sprocket 47 to the sixth rear sprocket 46 adjacent to the seventh rear sprocket 47. That is, in this embodiment, the upshifting actuation is the movement of the drive chain 3 from the rear sprocket 47 to the small sprocket 46 adjacent to the rear sprocket 47.

[0132] Multiple upshift promoting teeth 59U1, 59U2, and 59U3 include an upshift displacement tooth 59U1, an upshift initiation tooth 59U2, and an upshift recess tooth 59U3. An additional upshift promoting tooth 59U0 includes an additional upshift displacement tooth 59U0.

[0133] like Figure 7A As shown, the upshift displacement tooth 59U1 and the additional upshift displacement tooth 59U0 are configured to cause the drive chain 3 to move toward the sixth rear sprocket 46 during the upshift operation.

[0134] For example, during upshifting, when the inner link of the drive chain 3 is located at the additional upshift displacement tooth 59U0 and the outer link of the drive chain 3 is located at the upshift displacement tooth 59U1, the drive chain 3 is closer to the sixth rear sprocket 46 in both the additional upshift displacement tooth 59U0 and the upshift displacement tooth 59U1.

[0135] like Figure 7BAs shown, the upshift displacement tooth 59U1 has a second axial recess 59U1a. The second axial recess 59U1a is provided on the first axial inner surface 47b of the upshift displacement tooth 59U1. For example, the second axial recess 59U1a is provided on the first axial inner surface 47b of the upshift displacement tooth 59U1 in such a way that it is recessed from the first axial inner surface 47b to the first axial outer surface 47a in the axial direction about the rotation center axis X. The second axial recess 59U1a is disposed at least on the tooth tip 59U1b of the upshift displacement tooth 59U1.

[0136] The additional upshift displacement tooth 59U0 is located downstream of the upshift displacement tooth 59U1 in the drive rotation direction RD, and is configured adjacent to the upshift displacement tooth 59U1. The additional upshift displacement tooth 59U0 can be a regular drive tooth that does not have the function of an upshift displacement tooth.

[0137] The additional shifting gear tooth 59U0 has a third axial recess 59U0a. The third axial recess 59U0a is provided on the first axial inner surface 47b of the additional shifting gear tooth 59U0. The third axial recess 59U0a is provided on the first axial inner surface 47b of the additional shifting gear tooth 59U0 in such a way that it is recessed from the first axial inner surface 47b to the first axial outer surface 47a in the axial direction about the rotation center axis X. The third axial recess 59U0a is disposed at least on the tooth tip 59U0b of the additional shifting gear tooth 59U0.

[0138] The second axial recess 59U1a and the third axial recess 59U0a can be either recesses or inclined portions. The second axial recess 59U1a can extend radially inward from the tooth tip 59U1b of the lifting displacement tooth 59U1 about the rotation center axis X. The third axial recess 59U0a can extend radially inward from the tooth tip 59U0b of the additional lifting displacement tooth 59U0 about the rotation center axis X.

[0139] like Figure 7A As shown, the upshift initiation tooth 59U2 is configured to be the first to disengage from the drive chain 3 during the upshift operation. For example, during the upshift operation, when the inner link of the drive chain 3 is located at the upshift initiation tooth 59U2, the drive chain 3 begins to disengage from the upshift initiation tooth 59U2.

[0140] The upshift initiation tooth 59U2 is located upstream of the upshift displacement tooth 59U1 in the drive rotation direction RD of the seventh rear sprocket 47, and is configured adjacent to the upshift displacement tooth 59U1.

[0141] For example, in the circumferential direction about the rotation center axis X, no other first sprocket teeth 59 are arranged between the upshift initiation tooth 59U2 and the upshift displacement tooth 59U1, and the upshift initiation tooth 59U2 is arranged adjacent to the upshift displacement tooth 59U1 on the upstream side of the upshift displacement tooth 59U1 about the drive rotation direction RD of the seventh rear sprocket 47.

[0142] like Figure 7A As shown, the upshift initiation tooth 59U2 has an upshift first recess 59U2a. The upshift first recess 59U2a is provided on the first axial outer surface 47a of the upshift initiation tooth 59U2. For example, the upshift first recess 59U2a is provided on the first axial outer surface 47a of the upshift initiation tooth 59U2 in such a way that it is recessed from the first axial outer surface 47a to the first axial inner surface 47b in the axial direction about the rotation center axis X.

[0143] like Figure 7A As shown, the upshift recessed tooth 59U3 is used to assist the drive chain 3 in disengaging from the upshift initiation tooth 59U2 during the upshifting operation. For example, when the inner link of the drive chain 3 disengages from the upshift initiation tooth 59U2, the upshift recessed tooth 59U3 is configured such that the outer link of the drive chain 3 does not engage with the upshift recessed tooth 59U3.

[0144] The upshift recessed tooth 59U3 is positioned upstream of the upshift initiation tooth 59U2 in the drive rotation direction RD, adjacent to the upshift initiation tooth 59U2. For example, in the circumferential direction about the rotation center axis X, no other first sprocket teeth 59 are arranged between the upshift recessed tooth 59U3 and the upshift initiation tooth 59U2, and the upshift recessed tooth 59U3 is positioned upstream of the upshift initiation tooth 59U2 in the drive rotation direction RD.

[0145] like Figure 7A As shown, the shifting recess 59U3 has a second shifting recess 59U3a. The second shifting recess 59U3a is provided on the first axial outer surface 47a of the shifting recess 59U3. For example, the second shifting recess 59U3a is provided on the first axial outer surface 47a of the shifting recess 59U3 in such a way that it is recessed from the first axial outer surface 47a to the first axial inner surface 47b in the axial direction about the rotation center axis X.

[0146] ·Eighth rear sprocket

[0147] like Figure 5 , Figure 8A and Figure 8B As shown, the eighth rear sprocket 48 has a rotation center axis X, a second axial outer surface 48a, and a second axial inner surface 48b. The rotation center axis X is concentric with the rotation center axis of the aforementioned rear sprocket assembly 27. Figure 5 and Figure 8A As shown, the second axial outer surface 48a forms the outer surface of the eighth rear sprocket 48 in the axial direction about the rotation center axis X.

[0148] like Figure 5 and Figure 8B As shown, the second axial inner surface 48b forms the inner surface of the eighth rear sprocket 48 in the axial direction about the rotation center axis X. The second axial inner surface 48b is located on the opposite side of the second axial outer surface 48a in the axial direction about the rotation center axis X. The second axial inner surface 48b is configured such that, in its mounted state on the bicycle 1, it is located axially about the rotation center axis X... Figure 2 The axial center plane P shown is positioned relative to each other.

[0149] like Figure 8A and Figure 8B As shown, the eighth rear sprocket 48 includes a second outer ring 58, a plurality of second sprocket teeth 60, a second inner ring 62, and at least one second connecting arm 64. The second outer ring 58, the plurality of second sprocket teeth 60, the second inner ring 62, and at least one second connecting arm 64 are formed as a single integral component.

[0150] A plurality of second sprocket teeth 60 extend radially outward from the outer periphery 58a of the second outer annulus 58 about the rotation center axis X. In this embodiment, the total number of teeth of the plurality of second sprocket teeth 60 is 30.

[0151] like Figure 6C As shown, each of the plurality of second sprocket teeth 60 has a second maximum radial length L3 and a second maximum axial length L4. The second maximum radial length L3 is defined radially about the axis of rotation X. For example, the second maximum radial length L3 is the length in the radial direction about the axis of rotation X from the outer periphery 58a of the second outer annulus 58 to the tooth tip 60a of the plurality of second sprocket teeth 60. The outer periphery 58a of the second outer annulus 58 is defined by the tooth root circle 58b of the plurality of second sprocket teeth 60.

[0152] The second maximum axial length L4 is defined in the axial direction about the rotation center axis X. For example, the second maximum axial length L4 is the maximum length between the second axial outer surface 48a and the second axial inner surface 48b of the plurality of second sprocket teeth 60 in the axial direction about the rotation center axis X.

[0153] The second maximum axial length L4 is the maximum length between the second axial outer surface 48a and the second axial inner surface 48b at the position of the outer periphery 58a of the second outer annulus 58. The second maximum axial length L4 is shorter than the second maximum radial length L3.

[0154] like Figure 4 As shown, the second inner ring 62 is configured to connect to the sprocket support 19a of the rear hub assembly 19 when the eighth rear sprocket 48 is installed on the rear hub assembly 19, so as to transmit torque.

[0155] like Figure 5 , Figure 8A and Figure 8B As shown, the second inner annular body 62 has a second spline hole 62a. The second spline hole 62a forms the inner circumferential surface of the second inner annular body 62. Figure 4 As shown, the second spline hole 62a is configured to engage with the sprocket support 19a of the rear hub assembly 19 when the eighth rear sprocket 48 is mounted on the rear hub assembly 19. For example, the sprocket support 19a is a cylindrical spline shaft.

[0156] like Figure 8A and Figure 8B As shown, at least one second connecting arm 64 extends radially between the second outer annulus 58 and the second inner annulus 62. The at least one second connecting arm 64 is formed in a tapered shape from a third radial position RP3 toward a fourth radial position RP4. For example, the at least one second connecting arm 64 is formed in a tapered shape such that the third circumferential width W3 of the second connecting arm 64 gradually decreases as it moves from the third radial position RP3 toward the fourth radial position RP4. Details of the third circumferential width W3 will be described later.

[0157] like Figure 8A and Figure 8B As shown, at least one second connecting arm 64 has a second radially outer half 66 and a second radially inner half 68. At least one second connecting arm 64 has a second rivet hole 70. At least one second connecting arm 64 has a third rivet hole 72. The second rivet hole 70 provides... Figure 4 The first rivet 53a is inserted. The third rivet hole 72 is for... Figure 4 The second rivet 53b shown is inserted.

[0158] For example, at least one second connecting arm 64 includes a plurality of second connecting arms 64. Preferably, the total number of the plurality of second connecting arms 64 is 4 or more. In this embodiment, the total number of the plurality of second connecting arms 64 is 7.

[0159] like Figure 8A and Figure 8B As shown, the second radially outer half 66 is disposed radially about the rotation center axis X between the second radially outer annular body 58 and the second radially inner half 68. The second radially outer half 66 is integrally formed with the second radially outer annular body 58 and the second radially inner half 68.

[0160] The second radially outer half 66 has a third circumferential width W3. The third circumferential width W3 is defined by a third radial position RP3 about the rotation center axis X. The third circumferential width W3 is the length of the arc extending circumferentially about the rotation center axis X at the third radial position RP3. For example, the third circumferential width W3 is 11 mm or more. The third circumferential width W3 is 20 mm or less. That is, the third circumferential width W3 is 11 mm or more and 20 mm or less.

[0161] like Figure 8A and Figure 8B As shown, the second radially inner half 68 is located radially inward from the second radially outer half 66 about the rotation center axis X. The second radially inner half 68 is disposed between the second radially outer half 66 and the second inner annular body 62 about the rotation center axis X. The second radially inner half 68, the second radially outer half 66, and the second inner annular body 62 are integrally formed.

[0162] The second radial inner half 68 has a fourth circumferential width W4. The fourth circumferential width W4 is defined by the fourth radial position RP4 about the axis of rotation X. The fourth circumferential width W4 is the length of the arc extending circumferentially about the axis of rotation X at the fourth radial position RP4.

[0163] For example, the fourth circumferential width W4 is smaller than the third circumferential width W3. The fourth circumferential width W4 is 5 mm or more. The fourth circumferential width W4 is 10 mm or less. That is, the fourth circumferential width W4 is 5 mm or more and 10 mm or less.

[0164] like Figure 8A and Figure 8B As shown, the second rivet hole 70 is provided at the third radial position RP3 of the third circumferential width W3. The second rivet hole 70 has a hole diameter D2. For example, the ratio of the third circumferential width W3 to the hole diameter D2, W3 / D2, is 2.5 or more. The ratio of the third circumferential width W3 to the hole diameter D2, W3 / D2, is 5.0 or less.

[0165] That is, the ratio of the third circumferential width W3 to the aperture D2, W3 / D2, is 2.5 or more and 5.0 or less. In this embodiment, the third circumferential width W3 is 12.6 mm and the aperture D2 is 4.23 mm. In this case, the ratio of the third circumferential width W3 to the aperture D2, W3 / D2, is approximately 3.0.

[0166] The aforementioned eighth rear sprocket 48 is configured in the following way to smoothly facilitate downshifting. For example... Figure 9A and Figure 9BAs shown, the plurality of second sprocket teeth 60 include a plurality of downshift facilitating teeth 60D1, 60D2. The plurality of second sprocket teeth 60 may also include an additional downshift facilitating tooth 60D3.

[0167] Multiple downshifting actuating teeth 60D1, 60D2, and an additional downshifting actuating tooth 60D3 constitute a downshifting action that promotes the movement of the drive chain 3 from the seventh rear sprocket 47 adjacent to the eighth rear sprocket 48 to the eighth rear sprocket 48. That is, the downshifting action in this embodiment is the action of moving the drive chain 3 from the small sprocket 47 adjacent to the rear sprocket 48 to the rear sprocket 48.

[0168] The structure shown includes multiple downshift accelerator teeth 60D1, 60D2, and an additional downshift accelerator tooth 60D3. Figure 9A and Figure 9B In the middle, Figure 7A and Figure 7B The symbol “59D” is replaced with the symbol “60D”. Figure 7A The symbol “71D” in the text is replaced with the symbol “73D”.

[0169] That is, the multiple downshifting accelerator teeth 60D1, 60D2, and the additional downshifting accelerator tooth 60D3 are substantially the same as the multiple downshifting accelerator teeth 59D1, 59D2, and the additional downshifting accelerator tooth 59D3 of the seventh rear sprocket 47.

[0170] For example, in the above description of the structure of the downshifting action of the seventh rear sprocket 47, by understanding the main structure of the seventh rear sprocket 47 as the main structure of the eighth rear sprocket 48, the symbol "59D" in the seventh rear sprocket 47 is replaced with the symbol "60D", and the symbol "71D" in the seventh rear sprocket 47 is replaced with the symbol "73D", thereby understanding the structure of the multiple downshifting facilitators 60D1 and 60D2, as well as the structure of the additional downshifting facilitator 60D3.

[0171] Therefore, detailed descriptions of the multiple downshifting actuating teeth 60D1, 60D2, and the additional downshifting actuating tooth 60D3 are omitted below. The descriptions omitted here refer to the explanation of the structure of the downshifting action of the seventh rear sprocket 47.

[0172] The multiple downshift facilitating teeth 60D1, 60D2 include a downshift initiation tooth 60D1 and a downshift recessed tooth 60D2. The downshift initiation tooth 60D1 has a driving surface 60D1a and a non-driving surface 60D1b. The downshift initiation tooth 60D1 has a first axial recess 60D1e.

[0173] The downshift recessed tooth 60D2 has a driving surface 60D2a and a non-driving surface 60D2b. The downshift recessed tooth 60D2 has a first tooth tip 60D2c. The downshift recessed tooth 60D2 has a downshift recess 73D2. The downshift recess 73D2 includes a first downshift recess 73D2a and a second downshift recess 73D2b.

[0174] The additional downshift facilitator tooth 60D3 includes an additional downshift recess tooth 60D3. The additional downshift recess tooth 60D3 has a driving surface 60D3a and a non-driving surface 60D3b. The additional downshift recess tooth 60D3 has a second tooth tip 60D3c. The additional downshift recess tooth 60D3 has an additional downshift recess 73D3.

[0175] The aforementioned eighth rear sprocket 48 is configured in a way that facilitates upshifting smoothly. For example... Figure 9A and Figure 9B As shown, the plurality of second sprocket teeth 60 include a plurality of upshift promoting teeth 60U1, 60U2, and 60U3. The plurality of second sprocket teeth 60 may include an additional upshift promoting tooth 60U0.

[0176] Multiple upshifting actuating teeth 60U1, 60U2, and 60U3 constitute an upshifting actuation. Adding an additional upshifting actuating tooth 60U0 constitutes an upshifting actuation. The upshifting action is the movement of the drive chain 3 from the eighth rear sprocket 48 to the seventh rear sprocket 47 adjacent to the eighth rear sprocket 48. That is, in this embodiment, the upshifting action is the movement of the drive chain 3 from the rear sprocket 48 to the small sprocket 47 adjacent to the rear sprocket 48.

[0177] The structure shown includes multiple upshift accelerator teeth 60U1, 60U2, and 60U3, as well as a structure with an additional upshift accelerator tooth 60U0. Figure 9A and Figure 9B In the middle, Figure 7A and Figure 7B The symbol “59U” in the text is replaced with the symbol “60U”.

[0178] That is, the multiple upshift promoting teeth 60U1, 60U2, 60U3, and the additional upshift promoting tooth 60U0 and the multiple upshift promoting teeth 59U0, 59U1, 59U2, 59U3 of the seventh rear sprocket 47 are essentially the same.

[0179] For example, in the explanation of the structure of the upshifting action of the seventh rear sprocket 47, by understanding the main structure of the seventh rear sprocket 47 as the main structure of the eighth rear sprocket 48, and by replacing the symbol "59U" in the seventh rear sprocket 47 with the symbol "60U", it is possible to understand the structure of the multiple upshifting promoting teeth 60U1, 60U2, 60U3 and the structure of the additional upshifting promoting tooth 60U0.

[0180] Therefore, detailed descriptions of the multiple upshift actuating teeth 60U1, 60U2, 60U3, and the additional downshift actuating tooth 60U0 are omitted here. The omitted descriptions refer to the explanation of the structure of the upshifting action of the seventh rear sprocket 47.

[0181] The structure of multiple upshift promoting teeth 60U1, 60U2, 60U3, and an additional upshift promoting tooth 60U0 includes an upshift displacement tooth 60U1, an upshift initiation tooth 60U2, an upshift recess tooth 60U3, and an additional upshift promoting tooth 60U0. The upshift displacement tooth 60U1 has a second axial recess 60U1a. The upshift initiation tooth 60U2 has a first upshift recess 60U2a. The upshift recess tooth 60U3 has a second upshift recess 60U3a. The additional upshift displacement tooth 60U0 has a third axial recess 60U0a.

[0182] Symbol explanation:

[0183] 1. Bicycle

[0184] 3 Drive chain

[0185] 19 Rear Hub Assembly

[0186] 19a Sprocket Support

[0187] 27 Rear sprocket assembly

[0188] 47. Seventh rear sprocket

[0189] 47a First axial outer surface

[0190] 47b First axial inner surface

[0191] 48 Eighth rear sprocket

[0192] 48a Second axial outer surface

[0193] 48b Second axial inner surface

[0194] 57 First outer ring body

[0195] 58 Second outer ring body

[0196] 59 First sprocket tooth

[0197] 59D1 Downshift facilitator gear, downshift initiation gear

[0198] 59D1a driving surface

[0199] 59D1b Non-driving surface

[0200] 59D1e First Axial Recess

[0201] 59D2 downshift facilitator teeth, downshift recess teeth

[0202] 59D2c First Tooth Tip

[0203] 59D3 adds downshift facilitator teeth and downshift recess teeth.

[0204] 59D3c second tooth tip

[0205] 60 Second sprocket teeth

[0206] 60D1 downshift facilitator gear, downshift initiation gear

[0207] 60D1a driving surface

[0208] 60D1b non-driving surface

[0209] 60D1e First Axial Recess

[0210] 60D2 downshift facilitator teeth, downshift recess teeth

[0211] 60D2c first tooth tip

[0212] 60D3 adds downshift accelerator teeth and downshift recess teeth.

[0213] 60D3c second tooth tip

[0214] 59U0 Upshift facilitator gear, additional upshift displacement gear

[0215] 59U1 Upshift facilitator gear, upshift displacement gear

[0216] 59U2 Upshift facilitator gear, upshift initiation gear

[0217] 59U2a first recess of upshift

[0218] 59U3 Upshift facilitator teeth, upshift recess teeth

[0219] 59U3a second recess of upshift

[0220] 60U0 upshift facilitator gear, additional upshift displacement gear

[0221] 60U1 Upshift Promo Gear, Upshift Displacement Gear

[0222] 60U2 upshift facilitator gear, upshift initiation gear

[0223] 60U2a upshift first recess

[0224] 60U3 upshift facilitator teeth, upshift recess teeth

[0225] 60U3a upshift second recess

[0226] 61 First inner annular body

[0227] 61a First spline hole

[0228] 62 Second inner annulus

[0229] 62a Second spline hole

[0230] 63 First connecting arm

[0231] 64 Second connecting arm

[0232] 65 First radial outer half

[0233] 66 Second radial outer half

[0234] 67 First radial inner half

[0235] 68 Second radial inner half

[0236] 69 First rivet hole

[0237] 70 Second rivet hole

[0238] 71D2, 71D3 downshift recess

[0239] 71D2a first concave bottom surface

[0240] 71D3a second concave bottom surface

[0241] 73D2 downshift first recess

[0242] 73D3 downshift second recess

[0243] D1 and D2 apertures

[0244] L1 First maximum radial length

[0245] L2 First maximum axial length

[0246] L3 Second maximum radial length

[0247] L4 Second maximum axial length

[0248] P-axis center plane

[0249] RP1 First radial position

[0250] RP2 Second radial position

[0251] RP3 Third radial position

[0252] RP4 Fourth radial position

[0253] W1 First circumferential width

[0254] W2 Second Circumferential Width

[0255] W3 Third circumferential width

[0256] W4 Fourth Dimension Width

[0257] X is the axis of rotation.

Claims

1. A rear sprocket for a manually driven vehicle, comprising a central axis, an outer axial side, and an inner axial side, wherein the inner axial side is disposed axially opposite to the outer axial side about the central axis, and in the mounted state on the manually driven vehicle, is disposed axially opposite to the central axis, wherein... The rear sprocket of this human-powered vehicle has: Outer ring-shaped body; Multiple sprocket teeth extend radially outward from the outer periphery of the outer annulus about the axis of rotation; The inner ring-shaped body is configured to be connected to the sprocket support of the hub assembly in the assembled state where the rear sprocket is mounted on the hub assembly, so as to be able to transmit torque; At least one connecting arm extends radially between the outer annulus and the inner annulus, and has a radially outer half and a radially inner half located radially from the radially outer half toward the radially inner side. Each of the plurality of sprocket teeth has a maximum radial length defined in the radial direction and a maximum axial length defined in the axial direction that is shorter than the maximum radial length. The outer radial half has a first circumferential width defined by a first radial position about the axis of rotation. The radially inner half has a second circumferential width, which is smaller than the first circumferential width, defined by a second radial position about the axis of rotation. The at least one connecting arm is formed in a tapered shape such that the first circumferential width of the at least one connecting arm gradually decreases as it moves from the first radial position toward the second radial position. The outer annular body, the plurality of sprocket teeth, the inner annular body, and the at least one connecting arm are formed as a single integral component. The at least one connecting arm has a rivet hole located at the first radial position of the first circumferential width. The rivet hole is used to fix the rear sprocket to an adjacent rear sprocket, and the rivet hole is for inserting rivets. The rear sprockets include at least the seventh to the tenth rear sprockets. The rivets are at least two in number, wherein a first rivet connects the seventh to ninth rear sprockets to each other, and a second rivet connects the eighth to tenth rear sprockets to each other.

2. The rear sprocket for a manually driven vehicle according to claim 1, wherein, The at least one connecting arm includes multiple connecting arms.

3. The rear sprocket for a manually driven vehicle according to claim 2, wherein, The total number of the multiple connecting arms is 4 or more.

4. The rear sprocket for a manually driven vehicle according to claim 3, wherein, The rivet hole has a diameter. The ratio of the first circumferential width to the aperture is 2.5 or more.

5. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The inner annular body has a spline portion, which is configured to engage with the sprocket support body of the hub assembly in the assembled state.

6. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The first circumferential width is 11 mm or more.

7. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The first circumferential width is less than 20 mm.

8. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The second circumferential width is 5mm or more.

9. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The second circumferential width is less than 10 mm.

10. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The plurality of sprocket teeth include a plurality of downshifting actuating teeth, which are configured to facilitate a downshifting action that moves the drive chain from the small sprocket adjacent to the rear sprocket to the rear sprocket. The plurality of downshift facilitators include: The downshift initiation gear is configured to engage with the drive chain first during the downshifting action; and The downshift recessed tooth is located downstream of the downshift initiation tooth in the drive rotation direction of the rear sprocket and is configured adjacent to the downshift initiation tooth. In the circumferential direction about the axis of rotation, no other sprocket teeth are arranged between the downshift initiation tooth and the downshift recess tooth. The downshift recessed tooth has a downshift recessed portion, which is provided on the outer axial side of the downshift recessed tooth in such a way that it is recessed from the outer axial side to the inner axial side in the axial direction.

11. The rear sprocket for a manually driven vehicle according to claim 10, wherein, The first axial recess is provided on the inner axial side of the downshift initiation tooth in such a way that it is recessed from the inner axial side to the outer axial side in the axial direction. The first axial recess is disposed at least at the tooth tip of the downshift initiation tooth.

12. The rear sprocket for a manually driven vehicle according to claim 10, wherein, The downshift recess includes a first downshift recess and a second downshift recess. The first downshift recess and the second downshift recess are respectively provided on the outer axial surface of the downshift recess teeth in such a way that they are recessed from the outer axial surface to the inner axial surface in the axial direction. The downshift first recess has a first recess bottom surface, The second recessed portion of the downshift has a bottom surface. The first axial depth is defined as extending along the axial direction from the axial outer surface of the outer annulus to the bottom surface of the first recess. The second axial depth is defined as extending along the axial direction from the outer axial side of the outer annulus to the bottom surface of the second recess. The first axial depth is smaller than the second axial depth.

13. The rear sprocket for a manually driven vehicle according to claim 12, wherein, The downshift recessed tooth has a first tooth tip. The first recess of the downshift reaches the tip of the first tooth of the downshift recess tooth.

14. The rear sprocket for a manually driven vehicle according to claim 12, wherein, The downshift recessed tooth has a driving surface and a non-driving surface, the non-driving surface being located on the opposite side of the driving surface in the circumferential direction. The first downshift recess reaches the driving surface of the downshift recess tooth.

15. The rear sprocket for a manually driven vehicle according to claim 14, wherein, The second recessed part of the downshift did not reach the driving surface of the downshift recessed part tooth.

16. The rear sprocket for a manually driven vehicle according to claim 12, wherein, No other recesses are provided between the first downshift recess and the second downshift recess, and the first downshift recess and the second downshift recess are arranged adjacent to each other.

17. The rear sprocket for a manually driven vehicle according to any one of claims 1 to 4, wherein, The plurality of sprocket teeth include a plurality of upshift promoting teeth, which are configured to promote an upshifting action that drives the drive chain to move from the rear sprocket to a small sprocket adjacent to the rear sprocket.

18. The rear sprocket for a manually driven vehicle according to claim 17, wherein, The plurality of upshift facilitators include: The upshift displacement tooth is configured to displace the drive chain toward the small sprocket during the upshift action. The upshift initiation gear is configured to be the first to disengage from the drive chain during the upshift action; as well as Upshift recessed teeth, The shift start tooth has a first shift recess, which is provided on the outer axial side of the shift start tooth in such a way that it is recessed from the outer axial side to the inner axial side in the axial direction. In the circumferential direction about the axis of rotation, no other sprocket teeth are arranged between the upshift initiation tooth and the upshift displacement tooth, and the upshift initiation tooth is arranged adjacent to the upshift displacement tooth on the upstream side of the upshift displacement tooth in the drive rotation direction about the rear sprocket. The lifting recess tooth has a second lifting recess, which is provided on the outer axial side of the lifting recess tooth in such a way that it is recessed from the outer axial side to the inner axial side in the axial direction. In the circumferential direction, no other sprocket teeth are disposed between the upshift recess tooth and the upshift initiation tooth, and the upshift recess tooth is disposed adjacent to the upshift initiation tooth on the upstream side with respect to the drive rotation direction.

19. The rear sprocket for a manually driven vehicle according to claim 18, wherein, The second axial recess is provided on the inner axial side of the lifting displacement tooth in such a way that it is recessed from the inner axial side to the outer axial side in the axial direction. The second axial recess is disposed at least at the tooth tip of the shifting tooth.

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