Bicycle multiple sprocket arrangement

Abstract

It is an object of the present invention to provide a bicycle multiple sprocket assembly capable of providing a wide range of gear ratios. The bicycle multiple sprocket assembly includes a first sprocket and a second sprocket. The first sprocket includes a first number of teeth less than or equal to ten. The second sprocket includes a second number of teeth greater than or equal to forty-four.

Description

Background of the invention

[0001] Technical field The following invention relates to a bicycle multiple sprocket assembly, in particular to a bicycle multiple sprocket assembly, in particular to a bicycle multiple sprocket assembly having a rotational center axis and configured to be mounted to a bicycle hub assembly. Background information

[0002] A plurality of rear sprockets are attached to a rear bicycle hub assembly (see EP 1 342 657 A2, US 3 748 916 A, EP 2 022 712 A2). The respective rear sprockets have a different number of teeth. A combination of the number of teeth of the respective rear sprockets, i.e., a tooth combination of the rear sprockets, is determined, for example, according to a course, route, or course characteristic.

[0003] In cases where a rider wants to ride at high speed on a course or track with many flat sections or similar, a sprocket with a small number of teeth is usually used for the upper rear sprocket. On the other hand, in cases where the rider wants to ride comfortably on a course with numerous hills or similar, a sprocket with a large number of teeth is used for the lower rear sprocket.

[0004] With conventional rear sprockets, it's possible to set a gear ratio that prioritizes speed, but it's difficult to set a gear ratio that makes pedaling or riding easy. On the other hand, with conventional bicycle rear sprockets, it's possible to set a gear ratio that makes pedaling or riding very easy, but it's difficult to set a gear ratio that prioritizes speed. In other words, a conventional rear sprocket doesn't have a configuration that can simultaneously satisfy or ensure both the gear ratio that prioritizes speed and the gear ratio that makes pedaling or riding easy.

[0005] In view of this problem, it is an object of the present invention to provide a bicycle multiple sprocket assembly capable of setting a gear ratio in a wide range. SUMMARY

[0006] A bicycle multiple sprocket assembly according to the present invention has a rotational center axis and is configured to be mounted on a bicycle hub assembly. The bicycle multiple sprocket assembly includes a first sprocket having a first number of teeth less than or equal to ten, which is the smallest number of teeth; a second sprocket having a second number of teeth greater than or equal to fifty, which is the largest number of teeth; a third sprocket having a third number of teeth that is twelve, wherein the third sprocket is positioned between the first sprocket and the second sprocket in an axial direction parallel to the rotational center axis; a fourth sprocket having a fourth number of teeth, wherein the fourth sprocket is positioned between the second sprocket and the third sprocket in the axial direction;a fifth sprocket having a fifth number of teeth that is fourteen, wherein the fifth sprocket is positioned between the third sprocket and the fourth sprocket in the axial direction; a sixth sprocket having a sixth number of teeth, wherein the sixth sprocket is positioned between the fourth sprocket and the fifth sprocket in the axial direction; a seventh sprocket having a seventh number of teeth that is sixteen, wherein the seventh sprocket is positioned between the fifth sprocket and the sixth sprocket in the axial direction; an eighth sprocket having an eighth number of teeth, wherein the eighth sprocket is positioned between the sixth sprocket and the seventh sprocket in the axial direction; a ninth sprocket having a ninth number of teeth that is eighteen, wherein the ninth sprocket is positioned between the seventh sprocket and the eighth sprocket in the axial direction;a tenth sprocket having a tenth number of teeth that is twenty-eight, wherein the tenth sprocket is positioned between the eighth sprocket and the ninth sprocket in the axial direction; an eleventh sprocket having an eleventh number of teeth that is twenty-one, wherein the eleventh sprocket is positioned between the ninth sprocket and the tenth sprocket in the axial direction; and a twelfth sprocket having a twelfth number of teeth that is twenty-four, wherein the twelfth sprocket is positioned between the tenth sprocket and the eleventh sprocket in the axial direction. The total sprocket number is twelve.

[0007] The bicycle multiple sprocket assembly of the present invention can be configured as follows. The first number of teeth is nine, which is the smallest number of teeth. The second number of teeth is forty-four, which is the largest number of teeth. With this preferred bicycle multiple sprocket assembly, it is therefore possible to provide a wide range of gear ratios.

[0008] The bicycle multiple sprocket assembly of the present invention can be configured as follows. The first number of teeth is 10, which is the smallest number of teeth. The second number of teeth is one of 46, 48, and 50, which is the largest number of teeth. Thus, with this preferred bicycle multiple sprocket assembly, it is possible to provide a wide range of gear ratios.

[0009] A bicycle multiple sprocket assembly according to the present invention has a rotational center axis and is configured to be mounted on a bicycle hub assembly. The bicycle multiple sprocket assembly includes a first sprocket having a first number of teeth less than or equal to ten and a second sprocket having a second number of teeth greater than or equal to fifty. Furthermore, the bicycle multiple sprocket assembly includes ten additional sprockets positioned between the first sprocket and the second sprocket in an axial direction parallel to the rotational center axis. The total number of sprockets is twelve.

[0010] The bicycle multiple sprocket assembly of the present invention may be configured as follows. The bicycle multiple sprocket assembly further includes at least ten additional sprockets. The at least ten additional sprockets are positioned between the first sprocket and the second sprocket in an axial direction parallel to the rotational center axis. With this structure, it is possible to provide a gear ratio over a wide range and also smoothly change the gear ratio between the first sprocket and the second sprocket.

[0011] The bicycle multi-sprocket assembly of the present invention can be configured as follows. The axial length of each space between axially adjacent sprockets is 2.2 mm when the bicycle is equipped with a thick tire.

[0012] The bicycle multiple sprocket assembly of the present invention may be configured as follows. The axial thickness of each of the first sprocket, the second sprocket, and the additional sprockets is 1.6 mm.

[0013] The bicycle multiple sprocket assembly of the present invention may be configured as follows. The total axial length between the first sprocket and the second sprocket is 43.4 mm when the total number of sprockets is twelve.

[0014] The bicycle multiple sprocket assembly of the present invention can be configured as follows. The second sprocket includes at least one first shift assist projection. Consequently, it is possible to smoothly move a chain from a smaller adjacent sprocket to a second sprocket.

[0015] The bicycle multiple sprocket assembly of the present invention can be configured as follows. The first sprocket is designed to be mounted to the bicycle hub assembly via a mounting adapter. Thus, even if the number of sprockets is increased, the sprockets can be easily attached to the hub assembly.

[0016] The bicycle multiple sprocket assembly according to the present invention allows a wide range of gear ratios to be set. The bicycle multiple sprocket assembly according to the present invention also allows the gear ratio to be switched more smoothly between the first sprocket and the second sprocket. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of a bicycle according to the first to fifth embodiments of the present invention; Fig. 2 is a detailed view of a rear hub assembly according to the first to fifth embodiments; Fig. 3 is an exploded view of the first tubular member and a second tubular member on the rear hub assembly according to the first to fifth embodiments; Fig. 4 is a front view and a side view of a rear sprocket assembly according to the first embodiment; Fig. 5 is a front view and a side view of a rear sprocket assembly according to the second embodiment; Fig. 6 is a front view and a side view of a rear sprocket assembly according to the third embodiment; Fig. 7 is a front view and a side view of a rear sprocket assembly according to the fourth embodiment; Fig. 8 is a front view of a rear sprocket assembly according to the fifth embodiment; Fig. 9 is a side view of a rear sprocket assembly according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS - First Embodiment

[0017] In Fig. 1, a bicycle 1 of a first embodiment according to the present invention mainly includes a frame 11, a handle 13, a front hub assembly 15, a rear hub assembly 29, front and rear wheels 17, 19, front and rear brake devices 21, 23, a gear change section 30, and a drive section 25.

[0018] The frame 11 includes a frame body 11a and a front fork 11b. The front fork 11b is rotatably connected to the frame body 11a. The handlebar 13 is fixed to the front fork 11b. The front hub assembly 15 is supported on the front fork 11b. The front hub assembly 15 mainly includes a front hub shaft 15a and a front hub shell (not shown). Both ends of the front hub shaft 15a are supported on the front fork 11b. The front hub shell is rotatably provided with respect to the front hub shaft 15a. The front wheel 17 (e.g., spokes) is attached to the front hub shell.

[0019] The front and rear wheels 17, 19 are rotationally supported to the front fork 11b and a rear portion of the frame 11 by the front hub assembly 15 and the rear hub assembly 29, respectively.

[0020] The front and rear brake devices 21, 23 are operated by manipulating a brake lever 14. Since the front and rear brake devices 21, 23 have the same configuration as those for a conventional configuration, the description thereof is omitted.

[0021] The gear shifting section 30 is attached to the frame 11. The gear shifting section 30 includes a front derailleur 31 and a rear derailleur 33. The front derailleur 31 moves a bicycle chain 9 from a front sprocket to an adjacent front sprocket by a shifting operation of a shift lever (not shown) attached to, for example, the left side of the handlebar 13. The front derailleur 31 is attached to a seat tube of the frame 11 in the illustrated embodiment. The rear derailleur 33 moves the bicycle chain 9 from a rear sprocket to an adjacent rear sprocket by a shifting operation of a shift lever 33a attached to, for example, the right side of the handlebar 13. The rear derailleur 33 is attached to a connecting portion of a chain stay and a seat stay of the frame 11.

[0022] The drive section 25 mainly includes a crank assembly 27, a rear hub assembly 29, and a rear sprocket assembly 50 (an example of a bicycle multiple sprocket assembly).

[0023] The crank assembly 27 includes a crankshaft (not shown), a right crank arm 27a, and a left crank arm (not shown). The crankshaft is rotatably mounted to a lower portion of the frame 11, for example, a bottom bracket portion. Base ends of the right crank arm 27a and the left crank arm are non-rotatably mounted to both ends of the crankshaft, respectively. A pedal 34 is attached to a distal end of the right crank arm 27a and a distal end of the left crank arm. A front sprocket assembly 27b having the same configuration as such a conventional configuration is attached to the right crank arm 27a so as to be integrally rotatable. The front sprocket assembly 27b includes at least one front sprocket. For example, in the illustrated embodiment, the front sprocket assembly 27b includes two sprockets.

[0024] As in Fig. 1 and Fig. As shown in Figure 2, the rear hub assembly 29 is supported on the rear portion of the frame 11. The rear hub assembly 29 includes a rear hub shaft 35, a rear hub shell 37, a first tubular member 41, and a second tubular member 43 (an example of a mounting adapter).

[0025] The rear hub shaft 35 is held on the rear part of the frame 11 by a conventional wheel locking mechanism 49. The wheel locking mechanism 49 is the same as a conventional mechanism. The wheel locking mechanism 49 includes, for example, a pull rod 49a, a stationary nut 49b, and a movable nut 49c. The pull rod 49a extends along the rear hub shaft 35. The stationary nut 49b is screwed to one end of the pull rod 49a. The movable nut 49c is arranged at the other end of the pull rod 49a. The movable nut 49 is movable in an axial direction by a conventional cam mechanism. The stationary nut 49b and the movable nut 49c clamp the rear hub shaft 35 to the frame 11 when a lever 49d is operated.

[0026] The rear hub shell 37 is rotationally supported with respect to the rear hub shaft 35. The rear wheel 19 (e.g. spokes) is attached to the rear hub shell 37.

[0027] The rear hub shell 37 is rotatable about a shaft center C (an example of a rotational center axis) of the rear hub shaft 35. One of the ends (a left side in Fig. 2) The rear hub shell 37 is rotationally supported on the rear hub shaft 35 by a bearing assembly 39. An outer ring 39a of the bearing assembly 39 is fixed to an inner peripheral surface at one end of the rear hub shell 37. An inner ring 39b of the bearing assembly 39 is fixed to the rear hub shaft 35 by a lock nut 48 and a spacer 48a. Ball bearings 39c are arranged between the outer ring 39a of the bearing assembly 39 and the inner ring 39b of the bearing assembly 39.

[0028] On the other hand, the other end (a right side in Fig. 2) the rear hub shells 37 are non-rotatably supported on an inner member 47 disposed on an inner peripheral side of the first tubular member 41 (described below) through a spline structure 38. The spline structure 38 includes splines on an inner peripheral surface at the other end of the rear hub shell 37 and splines on an outer peripheral surface at one of the ends (the left side in Fig. 2) of the inner link 47.

[0029] The inner link 47 is rotatable about the shaft center C of the rear hub shaft 35. For example, the other end (the right side in Fig. 2) The inner member 47 is rotationally supported on the rear hub shaft 35 by the bearing assembly 69. An outer ring 69a of the bearing assembly 69 is fixed to an outer peripheral surface of the other end of the inner member 47. An inner ring 69b of the bearing assembly 69 is fixed to the rear hub shaft 35 by a lock nut 71 and a spacer 71b. Ball bearings 69c are arranged between the outer ring 69a of the bearing assembly and the inner ring 69b of the bearing assembly. Thus, the other end of the rear hub shell 37 and the inner member 47 is rotationally supported on the rear hub shaft 35 by the bearing assembly 69. Ratchet pawls 47a are formed on the outer peripheral portion of the inner member 47.

[0030] The first tubular member 41 is arranged around the shaft center C of the rear hub shaft 35, as shown in Fig. 3, rotatable. The first tubular member 41 includes a first body portion 41a, a plurality of first splines 41b, a plurality of ratchet teeth 41c, and a first inner screw portion 41d. The first body portion 41a is formed in a tubular shape. The first splines 41b are integrally formed with the outer peripheral portion of the first body portion 41a. A rear sprocket assembly 50 (a first rear sprocket assembly 51; described below) is mounted to the first splines 41b.

[0031] The ratchet teeth 41c are formed integrally with the inner peripheral portion of the first body portion 41a. The ratchet teeth 41c engage with the ratchet pawls 47a of the inner member 47. A conventionally used one-way clutch is configured by the engagement of the ratchet teeth 41c with the ratchet pawls 47a.

[0032] The first inner screw portion 41d is formed on an inner peripheral surface at the end of the first body portion 41a, for example, on an inner peripheral surface at the end of the second tubular member 43 side. A second outer screw portion 43e (described below) of the second tubular member 43 is screwed to the first inner screw portion 41d. Furthermore, a screw hole portion 41e is formed at the end where the first inner screw portion 41d is formed on the first body portion 41a. The screw hole portion 41e extends from the outer peripheral surface to the inner peripheral surface.

[0033] The first body portion 41a is rotationally supported to the inner member 47 by ball bearings 42a, 42b. For example, the ball bearings 42a, 42b are arranged on both sides of the ratchet teeth 41c in a direction along the rotation axis of the first body portion 41a. The ball bearings 42a are arranged between the inner peripheral surface of the first body portion 41a and one end side (the left side in Fig. 2) of the outer peripheral portion of the inner member 47c. Furthermore, the ball bearings 42b are arranged between the inner peripheral surface of the first body portion 41a and an outer ring 69a of the bearing assembly 69.

[0034] The second tubular member 43 is rotatable about the shaft center C of the rear hub shaft 35. The second tubular member 43 has a second main portion 43a, a coupling portion 43b, a plurality of second splines 43c, and a first outer screw portion 43d. The second body portion 43a is formed in a tubular shape. The outer diameter of the second body portion 43a is smaller than the outer diameter of the first body portion 41a. The coupling portion 43b is coupled to the first tubular member 41 (the first body portion 41a). The coupling portion 43b is formed in a flange shape and is integrally formed with one of the ends (the left side of the Fig. 2) of the second body portion 43a. The second outer screw portion 43e is formed on the outer peripheral portion of the coupling portion 43b. Furthermore, a groove portion 43f extending in a circumferential direction is formed on the outer peripheral portion of the coupling portion 43b. The second outer screw portion 43e is screwed into the first inner screw portion 41d of the first tubular member 41 (the first body portion 41a). In this state, a clamping member such as a screw member 44 is screwed into the screw hole portion 41e of the first tubular member 41 (the first body portion 41a) and engages with the groove portion 43f. Thus, the first tubular member 41 and the second tubular member 43 are coupled to each other. The second splines 43c are formed integrally with the outer peripheral portion of the second body portion 43a.A rear sprocket assembly 50 (a second rear sprocket assembly 52 as described below) is attached to the second splines 43c.

[0035] The first outer screw section 43d is on the outer peripheral surface (the right side in Fig. 2) is formed at the other end of the second body portion 43a. A second inner screw portion 71a of a lock nut 71 is screwed into the first outer screw portion 43d. For example, the second inner screw portion 71a of the lock nut 71 is screwed to the first outer screw portion 43d of the second tubular member 43 in a state where the rear sprocket assembly 50 is assembled to the rear hub assembly 29 (the first tubular member 41 and the second tubular member 43).

[0036] The rear sprocket assemblies 50 are configured to be mounted to the rear hub assembly 29. The rear sprocket assembly 50 has a rotational center axis. The rotational center axis corresponds to the rear hub shaft 35 or shaft center C of the rear hub shaft 35.

[0037] The rear sprocket assembly 50 is mounted to the first tubular member 51 and the second tubular member 43. The rear sprocket assembly 50 includes a plurality of rear sprockets 50A-50K.

[0038] As in Fig. 4, the rear sprocket assembly 50 includes a first rear sprocket assembly 51 and a second rear sprocket assembly 52.

[0039] The first rear sprocket assembly 51 is mounted on the first tubular member 41 (the first body portion 41a). The first rear sprocket assembly 51 includes first to ninth rear sprockets 50A-50I. The first to ninth rear sprockets 50A-50I are arranged on the outer peripheral portion of the first tubular member 41 in an axial direction parallel to the shaft center C of the rear hub shaft 35. The first rear sprocket 50A is arranged on the outer peripheral portion of the first tubular member 41 on one side of the rear hub shell 37. A spacer (not shown) is arranged between two sprockets adjacent to each other for the first to ninth rear sprockets 50A-50I.Instead of a spacer, some of the first to ninth rear sprockets 50A-50I may be fixed to a sprocket support member (not shown) so that the sprockets are fixed to the sprocket support member and mounted to the first tubular member 41 through the sprocket support member.

[0040] More specifically, first hole portions 53 are formed on the respective inner peripheral portions of the first to ninth rear sprockets 50A-50I, and a plurality of third splines 53a are formed on each of the first hole portions 53. The third splines 53a are in contact with the first splines 41b (see Fig. 3) are respectively engaged with the first tubular member 41. Consequently, the first to ninth rear sprockets 50A-50I are engaged with the first tubular member 41 such that the first to ninth rear sprockets 50A-50I are disposed on the outer peripheral portion of the first tubular member 41.

[0041] The second rear sprocket assembly 42 is fixed to the second tubular member 43 (the second body portion 43a). The second rear sprocket assembly 52 includes tenth and eleventh rear sprockets 50J, 50K. The tenth and eleventh rear sprockets 50J, 50K are arranged on the outer peripheral portion of the second tubular member 43 in an axial direction parallel to the shaft center C of the rear hub shaft 35. The tenth rear sprocket 50J is arranged on the outer peripheral portion of the second tubular member 43 such that it is adjacent to the ninth rear sprocket 50I in the axial direction. The eleventh rear sprocket 50K is arranged on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the tenth rear sprocket 50J at the most distant position from the first rear sprocket 50A in the axial direction.A spacer (not shown) is arranged between two sprockets which are at the tenth and eleventh rear sprockets 50J, 50K.

[0042] More specifically, a second hole portion 55 is formed at the respective inner peripheral portions of the tenth and eleventh rear sprockets 50J, 50K. A plurality of fourth splines 55a are formed at the second hole portion 55. The fourth splines 55a engage with the second splines 43c of the second tubular member 43, respectively. Consequently, the tenth and fifth rear sprockets 50J, 50K engage with the second tubular member 43, such that the tenth and eleventh rear sprockets 50J, 50K are disposed at the outer peripheral portion of the second tubular member 43.

[0043] As described above, the first rear sprocket assembly 51 is fixed to the first tubular member 41 (the first body portion 41a). Furthermore, the second rear sprocket assembly 52 is fixed to the second tubular member 43 (the second body portion 43a). In this state, the lock nut 71 (the second inner screw portion 71a) (see Fig. 2) is screwed to the second tubular member 43 (the first outer screw portion 43d) such that the rear sprocket assembly 50 (the first rear sprocket assembly 51 and the second rear sprocket assembly 52) is fixed to the rear hub assembly 29.

[0044] The first rear sprocket 50A is an example of a second rear sprocket. The second through tenth rear sprockets 50B through 50F are examples of at least five additional sprockets, at least eight additional sprockets, and nine additional sprockets. The eleventh rear sprocket 50K is an example of a first sprocket.

[0045] The designs / layouts of the first to eleventh rear sprockets 50A-50K are described in detail below. The first to eleventh rear sprockets 50A-50K are arranged in alphabetical order, with the first tubular link 51 and the second tubular link 43.

[0046] Specifically, the second to tenth rear sprockets 50B-50J are positioned between the first rear sprocket 50A and the eleventh rear sprocket 50K in the axial direction parallel to the shaft center C of the rear hub shaft 35. The second rear sprocket 50B is positioned between the first rear sprocket 50A and the third rear sprocket 50C in the axial direction. The third rear sprocket 50C is positioned between the second rear sprocket 50B and the fourth rear sprocket 50D in the axial direction. The fourth rear sprocket 50D is positioned between the third rear sprocket 50C and the fifth rear sprocket 50E in the axial direction. The fifth rear sprocket 50E is positioned between the fourth rear sprocket 50D and the sixth rear sprocket 50F in the axial direction.

[0047] The sixth rear sprocket 50F is positioned between the fifth rear sprocket 50E and the seventh rear sprocket 50G in the axial direction. The seventh rear sprocket 50G is positioned between the sixth rear sprocket 50F and the eighth rear sprocket 50H in the axial direction. The eighth rear sprocket 50H is positioned between the seventh rear sprocket 50G and the ninth rear sprocket 50I in the axial direction. The ninth rear sprocket 50I is positioned between the eighth rear sprocket 50H and the tenth rear sprocket 50J in the axial direction. The tenth rear sprocket 50J is positioned between the ninth rear sprocket 50I and the eleventh rear sprocket 50K in the axial direction.

[0048] In other words, the second rear sprocket 50B is positioned between the first rear sprocket 50A and the tenth rear sprocket 50J in the axial direction. The third rear sprocket 50C is positioned between the second rear sprocket 50B and the ninth rear sprocket 50I in the axial direction. The fourth rear sprocket 50D is positioned between the third rear sprocket 50C and the eighth rear sprocket 50H in the axial direction. The fifth rear sprocket 50E is positioned between the fourth rear sprocket 50D and the seventh rear sprocket 50G in the axial direction.

[0049] The sixth rear sprocket 50F is positioned between the fifth rear sprocket 50E and the seventh rear sprocket 50G in the axial direction. The seventh rear sprocket 50G is positioned between the fourth rear sprocket 50D and the eighth rear sprocket 50H in the axial direction. The eighth rear sprocket 50H is positioned between the third rear sprocket 50C and the ninth rear sprocket 50I in the axial direction. The ninth rear sprocket 50I is positioned between the second rear sprocket 50B and the tenth rear sprocket 50J in the axial direction. The tenth rear sprocket 50J is positioned between the first rear sprocket 50A and the eleventh rear sprocket 50K in the axial direction.

[0050] Finally, the configuration and tooth combination of the first to eleventh rear sprockets 50A-50K are described in detail. The root diameter of the first rear sprocket 50A is the largest among the first to eleventh rear sprockets 50A-50K. The root diameters of the second to tenth sprockets 50B-50J are gradually reduced in sequence from the second to tenth sprockets 50B-50J. The root diameter of the eleventh sprocket is the smallest among the first to eleventh rear sprockets 50A-50K.

[0051] The first rear sprocket 50A preferably includes at least one shift assist protrusion 54. The shift assist protrusion 54 catches the chain in front of the sprocket teeth of the first sprocket 50A when the rear derailleur 33 moves the chain from the second rear sprocket 50B to the first rear sprocket 50A. For example, the first rear sprocket 50A includes two shift assist protrusions 54. The two shift assist protrusions 54 are provided on the outer peripheral portion of the first rear sprocket 50A on the second rear sprocket 50B side. The two shift assist protrusions 54 are arranged at predetermined intervals around the rear hub shaft 35 (in a circumferential direction).

[0052] The axial thickness T1 of each of the first to eleventh rear sprockets 50A-50K is 1.6 mm. The axial length L1 of each space between axially adjacent rear sprockets is 2.18 mm. The total axial length TL1 between the first rear sprocket 50A and the eleventh rear sprocket 50K is 39.4 mm. The total axial length TL1 represents a distance between a surface of the first rear sprocket 50A on an opposite side from the second rear sprocket 50B and a surface of the eleventh rear sprocket 50K on an opposite side from the tenth rear sprocket 50J.

[0053] The first rear sprocket 50A has a first number of teeth (an example of a second number of teeth). The first number of teeth is greater than or equal to 44. In the embodiment, for example, the first number of teeth is 44, which is the largest number of teeth.

[0054] The second rear sprocket 50B has a second number of teeth. The second number of teeth is 38. The third sprocket 50C has a third number of teeth. The third number of teeth is 32. The fourth rear sprocket 50D has a fourth number of teeth. The fourth number of teeth is 27. The fifth rear sprocket 50E has a fifth number of teeth. The fifth number of teeth is 23. The sixth rear sprocket 50F has a sixth number of teeth. The sixth number of teeth is 20. The seventh rear sprocket 50G has a seventh number of teeth. The seventh number of teeth is 17. The eighth rear sprocket 50H has an eighth number of teeth. The eighth number of teeth is 15. The ninth rear sprocket 50I has a ninth number of teeth. The ninth tooth count is 13. The tenth rear sprocket, 50J, has a tenth tooth count. The tenth tooth count is eleven.

[0055] The eleventh rear sprocket 50K has an eleventh tooth count (an example of a first tooth count). The eleventh tooth count is less than or equal to 10. More specifically, the eleventh tooth count is less than or equal to nine. For example, in one embodiment, the eleventh tooth count is nine, which is the smallest tooth count. Second embodiment

[0056] A configuration of a bicycle of a second embodiment according to the present invention is substantially identical to the first embodiment except for a configuration of a rear sprocket assembly 150. Therefore, in the second embodiment, the rear sprocket assembly 150 will be described in detail, and explanations of the other configurations will be omitted. The omitted configuration corresponds to the configuration of the first embodiment. The same configurations as in the first embodiment have the same reference numerals.

[0057] As in Fig. 2 and Fig. As shown in Figure 5, the rear sprocket assembly 150 is configured to be mounted to the rear hub assembly 29. The rear sprocket assembly 150 has a rotational center axis. The rotational center axis corresponds to the rear hub shaft 35 or the hub center C of the rear hub shaft 35.

[0058] The rear sprocket assembly 150 is attached to the first tubular member 41 (the first body portion 41a) and the second tubular member 43 (the second body portion 43a). The rear sprocket assembly 150 includes a plurality of rear sprockets 150A-150G.

[0059] The first to sixth rear sprockets 150A-150F are arranged on the outer peripheral portion of the first tubular member 41 in an axial direction parallel to the shaft center C of the rear hub shaft 35. The first rear sprocket 150A is arranged on the outer peripheral portion of the first tubular member 41 on the rear hub shell 37 side. The first to sixth rear sprockets 150A-150F are arranged on the outer peripheral portion of the first tubular member 41 by the same spline coupling as in the first embodiment.

[0060] The seventh rear sprocket 150G is arranged on the outer peripheral portion of the second tubular member 43 in an axial direction parallel to the shaft center C of the rear hub shaft 35. The seventh rear sprocket 150G is arranged on the outer peripheral portion of the second tubular member 43 so as to be connected to the sixth rear sprocket 150F at the farthest position from the first rear sprocket 150A in the axial direction. The seventh rear sprocket 150G is arranged on the outer peripheral portion of the second tubular member 43 through the same spline coupling as in the first embodiment. The first rear sprocket 150A is an example of a second sprocket. The second to sixth rear sprockets 150F are an example of five additional sprockets. The seventh rear sprocket 150G is an example of a first sprocket.

[0061] In the second embodiment, the first tubular member 41 is formed to be shorter in the axial direction than that in the first embodiment. The second tubular member 43 is formed to be shorter in the axial direction than that in the first embodiment. The total number of the first to sixth rear sprockets 150A-150F is less than the total number of the first to ninth rear sprockets 50A-50I in the first embodiment. Also, the number of the seventh rear sprockets 150G is less than the number of the tenth and eleventh rear sprockets 50J, 50K in the first embodiment.

[0062] Layouts of the first to seventh rear sprockets 150A-150G are described in detail below. The first to seventh rear sprockets 150A-150G are arranged on the first tubular link 41 in alphabetical order.

[0063] Specifically, the second to sixth rear sprockets 150B-150F are positioned between the first rear sprocket 150A and the seventh rear sprocket 150G in the axial direction parallel to the shaft center C of the rear hub shaft 35. The second rear sprocket 150B is positioned between the first rear sprocket 150A and the third rear sprocket 150C in the axial direction. The third rear sprocket 150C is positioned between the second rear sprocket 150B and the fourth rear sprocket 150D in the axial direction. The fourth rear sprocket 150D is positioned between the third rear sprocket 150C and the fifth rear sprocket 150E in the axial direction. The fifth rear sprocket 150E is positioned between the fourth rear sprocket 150D and the sixth rear sprocket 150F in the axial direction.The sixth rear sprocket 150F is positioned between the fifth rear sprocket 150E and the seventh rear sprocket 150G in the axial direction.

[0064] In other words, the sixth rear sprocket 150F is positioned between the first rear sprocket 150A and the seventh rear sprocket 150G in the axial direction. The second rear sprocket 150B is positioned between the first rear sprocket 150A and the sixth rear sprocket 150F in the axial direction. The fifth rear sprocket 150E is positioned between the second rear sprocket 150B and the sixth rear sprocket 150F in the axial direction. The third rear sprocket 150C is positioned between the second rear sprocket 150B and the sixth rear sprocket 150F in the axial direction. The fourth rear sprocket 150D is positioned between the third rear sprocket 150C and the fifth rear sprocket 150E in the axial direction.

[0065] Finally, a configuration and tooth combination of the first to seventh rear sprockets 150A-150G are described in detail. A root diameter of the first rear sprocket 150A is the largest among the first to seventh rear sprockets 150A-150G. The root diameters of the second to sixth rear sprockets 150B-150F are gradually reduced in the order of the second to sixth sprockets 150B-150F. A root diameter of the seventh sprocket 150G is the smallest among the first to seventh rear sprockets 150A-150G.

[0066] The first rear sprocket 150A preferably includes at least one shift assist protrusion 154. For example, the first rear sprocket 150A includes two shift assist protrusions 154. The two shift assist protrusions 154 are provided on the outer peripheral portion of the first rear sprocket 150A. The two shift assist protrusions 154 are arranged at a predetermined interval around the rear hub shaft 35 (in a circumferential direction).

[0067] The axial thickness T2 of each of the first to seventh rear sprockets 150A-150G is 1.6 mm. The axial length L2 of each space between axially adjacent rear sprockets is 2.18 mm. The total axial length TL2 between the first rear sprocket 150A and the seventh rear sprocket 150G is 24.28 mm. The total axial length TL2 corresponds to a distance between a surface of the first rear sprocket 150A on an opposite side to the second rear sprocket 150B and a surface of the seventh rear sprocket 150G on an opposite side to the sixth rear sprocket 150F.

[0068] The first rear sprocket 150A has a first number of teeth (an example of a second number of teeth). The first number of teeth is greater than or equal to 44. For example, in the embodiment, the first number of teeth is 46, which is the largest number of teeth.

[0069] The second rear sprocket 150B has a second number of teeth. The second number of teeth is 36. The third rear sprocket 150C has a third number of teeth. The third number of teeth is 28. The fourth rear sprocket 150D has a fourth number of teeth. The fourth number of teeth is 22. The fifth rear sprocket 150E has a fifth number of teeth. The fifth number of teeth is 17. The sixth rear sprocket 150F has a sixth number of teeth. The sixth number of teeth is 13.

[0070] The seventh rear sprocket 150G has a seventh number of teeth (an example of a first number of teeth). The seventh number of teeth is less than or equal to ten. For example, in the embodiment, the seventh number of teeth is ten, which is the smallest number of teeth. Third embodiment

[0071] A configuration of a bicycle of a third embodiment according to the present invention is substantially identical to the first embodiment except for a configuration of the rear sprocket assembly 250. Furthermore, the configuration of the rear sprocket assembly 250 is substantially identical to that of the second embodiment except for the configuration of the rear sprockets 250A through 250G.

[0072] For this reason, the layouts of the rear sprockets 150A-150G in the third embodiment will be described in detail, and explanations of the other configurations will be omitted. The configurations omitted herein correspond to the configurations of the first and second embodiments. The same configurations as those in the first and second embodiments have the same reference numerals.

[0073] As in the Fig. 2 and Fig. As shown in Figure 6, the rear sprocket assembly 250 is attached to the first tubular member 41 (the first body portion 41a) and the second tubular member 43 (the second body portion 43a). The rear sprocket assembly 250 includes a plurality of rear sprockets 250A-250G.

[0074] The first to sixth rear sprockets 150A-150F are arranged on the outer peripheral portion of the first tubular member 41 in the same manner as in the second embodiment. The seventh rear sprocket 150G is arranged on the outer peripheral portion of the second tubular member 43 in the same manner as in the second embodiment.

[0075] The first to sixth rear sprockets 150A - 150G are respectively arranged on the outer peripheral portions of the first and second tubular members 41, 43 by the same spline coupling as in the first embodiment.

[0076] The root diameter of the first rear sprocket 250A is the largest among the first to seventh rear sprockets 250A-250G. The root diameters of the second to sixth rear sprockets 250B-250F gradually decrease in the order of the second to sixth rear sprockets 250B-250F. The root diameter of the seventh rear sprocket 250G is the smallest among the first to sixth rear sprockets 250A-250G.

[0077] The first rear sprocket 250A preferably includes at least one shift assist protrusion 254. For example, the first rear sprocket 250A includes two shift assist protrusions 254. The two shift assist protrusions 254 are provided on the outer peripheral portion of the first rear sprocket 250A. The two shift assist protrusions 254 are arranged at a predetermined interval around the rear hub shaft 35 (in a circumferential direction).

[0078] The axial thickness T3 of each of the first to seventh rear sprockets 250A-250G is 1.6 mm. The axial length L3 of each space between the axially adjacent rear sprockets is 2.18 mm. The total axial length TL3 between the first rear sprocket 250A and the eleventh rear sprocket 250K is 24.28 mm. The total axial length TL3 corresponds to a distance between a surface of the first rear sprocket 250A on an opposite side to the second rear sprocket 250B and a surface of the seventh rear sprocket 250G on an opposite side to the sixth rear sprocket 250F.

[0079] The first rear sprocket 250A has a first number of teeth (an example of a second number of teeth). The first number of teeth is greater than or equal to 44. In the embodiment, for example, the first number of teeth is 50, which is the largest number of teeth.

[0080] The second rear sprocket 250B has a second number of teeth. The second number of teeth is 38. The third rear sprocket 250C has a third number of teeth. The third number of teeth is 29. The fourth rear sprocket 250D has a fourth number of teeth. The fourth number of teeth is 22. The fifth rear sprocket 250E has a fifth number of teeth. The fifth number of teeth is 17. The sixth rear sprocket 250F has a sixth number of teeth. The sixth number of teeth is 13.

[0081] The seventh rear sprocket 250G has a seventh tooth count (an example of a first tooth count). The seventh tooth count is less than or equal to ten.

[0082] For example, in the embodiment, the seventh tooth number is ten, which is the smallest tooth number. Fourth embodiment

[0083] A configuration of a bicycle of a fourth embodiment according to the present invention is substantially identical to that of the first embodiment except for a configuration of a rear sprocket assembly 350. For this reason, in the fourth embodiment, the rear sprocket assembly 350 will be described in detail, and explanations of the other configurations will be omitted. The configurations omitted herein correspond to the configurations according to the first embodiment. The same configurations as those in the first embodiment have the same reference numerals.

[0084] As in the Fig. 2 and Fig. As shown in Figure 7, the rear sprocket assembly 350 is configured to be mounted on the rear hub assembly 29. The rear sprocket assembly 350 has a rotational center axis. The rotational center axis corresponds to the rear hub shaft 35 or a hub center C of the rear hub shaft 35.

[0085] The rear sprocket assembly 350 is attached to a first tubular member 41 and a second tubular member 43. The rear sprocket assembly 350 includes a plurality of rear sprockets 350A-350I.

[0086] For example, the rear sprocket assembly 350 includes a first rear sprocket assembly 351 and a second rear sprocket assembly 352.

[0087] The first rear sprocket assembly 351 is fixed to the first tubular member 41 (the first body portion 41a). The rear sprocket assembly 351 includes first to ninth rear sprockets 350A-350I. The first to ninth rear sprockets 350A-350I are arranged on the outer peripheral portion of the first tubular member 41 in an axial direction parallel to the shaft center C of the rear hub shaft 35. The first rear sprocket 350A is arranged on the outer peripheral portion of the first tubular member 41 on one side of a rear hub shell 37. The first to ninth rear sprockets 350A-350E are arranged on the outer peripheral portion of the first tubular member 41 by the same spline coupling as in the first embodiment.

[0088] The second rear sprocket assembly 352 is fixed to the second tubular member 43 (the second body portion 43a). The second rear sprocket assembly 352 includes tenth to twelfth rear sprockets 350J-350I. The tenth to twelfth rear sprockets 350J-350I are arranged on the outer peripheral portion of the second tubular member 43 in the axial direction parallel to the shaft center C of the rear hub shaft 35. The tenth rear sprocket 350J is arranged on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the ninth rear sprocket 350I in the axial direction. The eleventh rear sprocket 350K is disposed on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the tenth rear sprocket 350J in the axial direction.The twelfth rear sprocket 350K is disposed on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the eleventh rear sprocket 350K at the most distal position from the first rear sprocket 350A in the axial direction.

[0089] The first rear sprocket 350A is an example of a second sprocket. The second through eleventh rear sprockets 350B–350K are examples of at least five additional sprockets and at least eight additional sprockets. The twelfth rear sprocket 350I is an example of a first sprocket.

[0090] Layouts / designs of the first through twelfth rear sprockets 350A-350I are described in detail below. The first through twelfth sprockets 350A-350I are arranged on the first tubular member 41 and the second tubular member 43 in alphabetical order.

[0091] Specifically, the second to eleventh rear sprockets 350B-350K are arranged between the first rear sprocket 350A and the twelfth rear sprocket 350I in the axial direction parallel to the shaft center C of the rear hub shaft 35. The second rear sprocket 350B is positioned between the first rear sprocket 350A and the third rear sprocket 350C in the axial direction. The third rear sprocket 350C is positioned between the second rear sprocket and the fourth rear sprocket in the axial direction. The fourth rear sprocket 350D is positioned between the third rear sprocket 350C and the fifth rear sprocket 350E in the axial direction. The fifth rear sprocket 350E is positioned between the fourth rear sprocket 350D and the sixth rear sprocket 350F in the axial direction.

[0092] The sixth rear sprocket 350F is positioned between the fifth rear sprocket 350E and the seventh rear sprocket 350G in the axial direction. The seventh rear sprocket 350G is positioned between the sixth rear sprocket 350F and the eighth rear sprocket 350H in the axial direction. The eighth rear sprocket 350H is positioned between the seventh rear sprocket 350G and the ninth rear sprocket 350I in the axial direction. The ninth rear sprocket 350I is positioned between the eighth rear sprocket 350H and the tenth rear sprocket 350J in the axial direction. The tenth rear sprocket 350J is positioned between the ninth rear sprocket 350I and the eleventh rear sprocket 350K in the axial direction. The eleventh rear sprocket 350K is positioned between the tenth rear sprocket 350J and the twelfth rear sprocket 350I in the axial direction.

[0093] In other words, the second rear sprocket 350B (an example of a fourth sprocket) is positioned between the first rear sprocket 350A (an example of a second sprocket) and the eleventh rear sprocket 350K (an example of a third sprocket) in the axial direction. The third rear sprocket 350C (an example of a sixth sprocket) is positioned between the second rear sprocket 350B (an example of a fourth sprocket) and the tenth rear sprocket 350J (an example of a fifth sprocket) in the axial direction. The fourth rear sprocket 350D (an example of an eighth sprocket) is positioned between the third rear sprocket 350C (an example of a sixth sprocket) and the ninth rear sprocket 350I (an example of a seventh sprocket) in the axial direction. The fifth rear sprocket 350E (an example of aExample of a tenth sprocket) is positioned between the fourth rear sprocket 350D (an example of an eighth sprocket) and the eighth rear sprocket 350H (an example of a ninth sprocket) in the axial direction.

[0094] The sixth rear sprocket 350F (an example of a twelfth rear sprocket) is positioned between the fifth rear sprocket 350E (an example of a tenth sprocket) and the seventh rear sprocket 350G (an example of an eleventh sprocket) in the axial direction. The seventh rear sprocket 350G (an example of an eleventh sprocket) is positioned between the fifth rear sprocket 350E (an example of a tenth sprocket) and the eighth rear sprocket 350H (an example of a ninth sprocket) in the axial direction. The eighth rear sprocket 350H (an example of a ninth sprocket) is positioned between the fourth rear sprocket 350D (an example of an eighth sprocket) and the ninth rear sprocket 350I (an example of a seventh sprocket) in the axial direction.The ninth rear sprocket 350I (an example of a seventh sprocket) is positioned between the third rear sprocket 350C (an example of a sixth sprocket) and the tenth rear sprocket 350J (an example of a fifth sprocket) in the axial direction. The tenth rear sprocket 350J (an example of a fifth sprocket) is positioned between the second rear sprocket 350B (an example of a fourth sprocket) and the eleventh rear sprocket 350K (an example of a third sprocket) in the axial direction. The eleventh rear sprocket 350K (an example of a third sprocket) is positioned between the first rear sprocket 350A (an example of a second sprocket) and the twelfth rear sprocket 350I (an example of a first sprocket) in the axial direction.

[0095] Finally, a configuration of the first to twelfth rear sprockets 350A-350I is described in detail. The root diameter of the first rear sprocket 350A is the largest among the first to twelfth rear sprockets 350A-350I. The root diameters of the second to eleventh rear sprockets 350B-350K are gradually reduced in the order of the second to eleventh rear sprockets 350B-350K. The root diameter of the twelfth rear sprocket 350I is the smallest among the first to twelfth rear sprockets 350A-350I.

[0096] The first rear sprocket 350A preferably includes at least one shift assist protrusion 354. For example, the first rear sprocket 350A includes two shift assist protrusions 354. The two shift assist protrusions 354 are provided on the outer peripheral portion of the first rear sprocket 350A. The two shift assist protrusions 354 are arranged at a predetermined interval around the rear hub shaft 35 (in a circumferential direction).

[0097] The axial thickness T4 of each of the first through twelfth rear sprockets 350A-350I is 1.6 mm. The axial length L4 of each space between axially adjacent rear sprockets is 2.2 mm. The total axial length TL4 between the first rear sprocket 350A and the twelfth rear sprocket 350I is 43.4 mm. The total axial length TL4 corresponds to a distance between a surface of the first rear sprocket 350A on an opposite side to the second rear sprocket 350B and a surface of the twelfth rear sprocket 350I on the opposite side to the eleventh rear sprocket 350K.

[0098] The first rear sprocket 350A has a first number of teeth (an example of a second number of teeth). The first number of teeth is greater than or equal to 44. In the embodiment, for example, the first number of teeth is 50, which is the largest number of teeth.

[0099] The second rear sprocket 350B has a second number of teeth. The second number of teeth is 44. The third rear sprocket 350C has a third number of teeth. The third number of teeth is 38. The fourth rear sprocket 350D has a fourth number of teeth. The fourth number of teeth is 33. The fifth rear sprocket 350E has a fifth number of teeth. The fifth number of teeth is 28. The sixth rear sprocket 350F has a sixth number of teeth. The sixth number of teeth is 24. The seventh rear sprocket 350G has a seventh number of teeth. The seventh number of teeth is 21. The eighth rear sprocket 350H has an eighth number of teeth. The eighth number of teeth is 18. The ninth rear sprocket 350I has a ninth number of teeth. The ninth tooth count is 16. The tenth rear sprocket, 350J, has a tenth tooth count. The tenth tooth count is 14. The eleventh rear sprocket, 350K, has an eleventh tooth count. The eleventh tooth count is twelve.

[0100] The twelfth rear sprocket 350I has a twelfth tooth count (an example of a first tooth count). The twelfth tooth count is less than or equal to ten. In the embodiment, for example, the twelfth tooth count is ten, which is the smallest tooth count. Fifth embodiment

[0101] A configuration of a bicycle of a fifth embodiment according to the present invention is substantially identical to the first embodiment except for a configuration of a rear sprocket assembly 450. For this reason, in the fifth embodiment, the rear sprocket assembly 450 will be described in detail, and explanations of the other configurations will be omitted. The configuration that is omitted corresponds to the configuration according to the first embodiment. The same configuration as that in the first embodiment will be given the same reference numerals.

[0102] As in the Fig. 2 and Fig. As shown in Figure 8, the rear sprocket assembly 450 is configured to be mounted to the rear hub assembly 29. The rear sprocket assembly 450 has a rotational center axis. The rotational center axis corresponds to the rear hub shaft 35 or a hub center C of the rear hub shaft 35.

[0103] The rear sprocket assembly 450 is attached to a first tubular member 41 and a second tubular member 43. The rear sprocket assembly 450 includes a plurality of rear sprockets 450A-450I.

[0104] For example, the rear sprocket assembly 450 includes a first rear sprocket assembly 451 and a second rear sprocket assembly 452.

[0105] The first rear sprocket assembly 451 is fixed to the first tubular member 41 (the first body portion 41a). The first rear sprocket assembly 451 includes first to ninth rear sprockets 450A-450I. The first to ninth rear sprockets 450A-450I are arranged on the outer peripheral portion of the first tubular member 41 in an axial direction parallel to the shaft center C of the rear hub shaft 35. The first rear sprocket 450A is arranged on the outer peripheral portion of the first tubular member 41 on one side of a rear hub shell 37. The first to ninth rear sprockets 450A-450I are arranged on the outer peripheral portion of the first tubular member 41 by the same spline coupling as in the first embodiment.

[0106] The second rear sprocket assembly 452 is fixed to the second tubular member 43 (the second body portion 43a). The second rear sprocket assembly 452 includes tenth to twelfth rear sprockets 450J-450I. The tenth to twelfth rear sprockets 450J-450I are arranged on the outer peripheral portion of the second tubular member 43 in the axial direction parallel to the shaft center C of the rear hub shaft 35. The tenth rear sprocket 450J is arranged on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the ninth rear sprocket 450I in the axial direction. The eleventh rear sprocket 450K is arranged on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the tenth rear sprocket 450J in the axial direction.The twelfth rear sprocket 450K is arranged on the outer peripheral portion of the second tubular member 43 so as to be adjacent to the eleventh rear sprocket 450K at the most distant position from the first rear sprocket 450A in the axial direction.

[0107] The first rear sprocket 450A is an example of a second sprocket. The second through eleventh rear sprockets 450B–450K are examples of at least five additional sprockets and at least eight additional rear sprockets. The twelfth rear sprocket 450I is an example of a first sprocket.

[0108] Layouts / designs of the first through twelfth rear sprockets 450A-450I are described in detail below. The first through twelfth rear sprockets 450A-450I are arranged on the first tubular member 41 and the second tubular member 43 in alphabetical order.

[0109] Specifically, the second to twelfth rear sprockets 450B-450K are arranged between the first rear sprocket 450A and the twelfth rear sprocket 450I in the axial direction parallel to the shaft center C of the rear hub shaft 35. The second rear sprocket 450B is positioned between the first rear sprocket 450A and the third rear sprocket 450C in the axial direction. The third rear sprocket 450C is positioned between the second rear sprocket 450B and the fourth rear sprocket 450D in the axial direction. The fourth rear sprocket 450D is positioned between the third rear sprocket 450C and the fifth rear sprocket 450E in the axial direction. The fifth rear sprocket 450E is positioned between the second rear sprocket 450D and the sixth rear sprocket 450F in the axial direction.

[0110] The sixth rear sprocket 450F is positioned between the fifth rear sprocket 450E and the seventh rear sprocket 450G in the axial direction. The seventh rear sprocket 450G is positioned between the sixth rear sprocket 450F and the eighth rear sprocket 450H in the axial direction. The eighth rear sprocket 450H is positioned between the seventh rear sprocket and the ninth rear sprocket 450I in the axial direction. The ninth rear sprocket 450I is positioned between the eighth rear sprocket 450H and the tenth rear sprocket 450J in the axial direction. The tenth rear sprocket 450J is positioned between the ninth rear sprocket 450I and the eleventh rear sprocket 450K in the axial direction. The eleventh rear sprocket 450K is positioned between the tenth rear sprocket 450J and the twelfth rear sprocket 450I in the axial direction.

[0111] In other words, the second rear sprocket 450B (an example of a fourth sprocket) is positioned between the first rear sprocket 450A (an example of a second sprocket) and the eleventh rear sprocket 450K (an example of a third sprocket) in the axial direction. The third rear sprocket 450C (an example of a sixth sprocket) is positioned between the second rear sprocket 450B (an example of a fourth sprocket) and the tenth rear sprocket 450J (an example of a fifth sprocket) in the axial direction. The fourth rear sprocket 450D (an example of an eighth sprocket) is positioned between the third rear sprocket 450C (an example of a sixth sprocket) and the ninth rear sprocket 450I (an example of a seventh sprocket) in the axial direction.The fifth rear sprocket 450E (an example of a tenth sprocket) is positioned between the fourth rear sprocket 450D (an example of an eighth sprocket) and the eighth rear sprocket 450H (an example of a ninth sprocket) in the axial direction.

[0112] The sixth rear sprocket 450F (an example of a twelfth sprocket) is positioned between the fifth rear sprocket 450E (an example of a tenth sprocket) and the seventh rear sprocket 450G (an example of an eleventh sprocket) in the axial direction. The seventh rear sprocket 450G (an example of an eleventh sprocket) is positioned between the fifth rear sprocket 450E (an example of a tenth sprocket) and the eighth rear sprocket 450H (an example of a ninth sprocket) in the axial direction. The eighth rear sprocket 450H (an example of a ninth sprocket) is positioned between the fourth rear sprocket 450D (an example of an eighth sprocket) and the ninth rear sprocket 450I (an example of a seventh sprocket) in the axial direction.The ninth rear sprocket 450I (an example of a seventh sprocket) is positioned between the third rear sprocket 450C (an example of a sixth sprocket) and the tenth rear sprocket 450J (an example of a fifth sprocket) in the axial direction. The tenth rear sprocket 450J (an example of a fifth sprocket) is positioned between the second rear sprocket 450B (an example of a fourth sprocket) and the eleventh rear sprocket 450K (an example of a third sprocket) in the axial direction. The eleventh rear sprocket 450K (an example of a third sprocket) is positioned between the first rear sprocket 450A (an example of a second sprocket) and the twelfth rear sprocket 450I (an example of a first sprocket) in the axial direction.

[0113] Finally, a configuration of the first to twelfth rear sprockets 450A - 450I is described in detail. A root diameter of the first rear sprocket 450A is the largest of the first to twelfth rear sprockets 450A - 450I. The root diameters of the second to eleventh sprockets 450B - 450K gradually decrease in the order of the second to eleventh sprockets 450B - 450K. A root diameter of the twelfth sprocket 450I is the smallest of the first to twelfth rear sprockets 450A - 450I.

[0114] The first rear sprocket 450A preferably includes at least one shift assist protrusion (not shown). For example, the first rear sprocket 450A may include six shift assist protrusions. The six shift assist protrusions are provided on the outer peripheral portion of the first rear sprocket 450A. The six shift assist protrusions are arranged at a predetermined interval around the rear hub shaft 35 (in a circumferential direction).

[0115] The axial thickness T4 of each of the first through twelfth rear sprockets 450A-450I is 1.6 mm. The axial length L4 of each space between axially adjacent rear sprockets is 2.2 mm. The total axial length TL4 between the first rear sprocket 450A and the twelfth rear sprocket 450I is 43.4 mm. The total axial length TL4 corresponds to a distance between a surface of the first rear sprocket 450A on an opposite side to the second rear sprocket 450B and a surface of the twelfth rear sprocket 450I on an opposite side to the eleventh rear sprocket 450K.

[0116] The first rear sprocket 450A has a first number of teeth (an example of a second number of teeth). The first number of teeth is greater than or equal to 48. In the embodiment, for example, the first number of teeth is 48, which is the largest number of teeth.

[0117] The second rear sprocket 450B has a second number of teeth. The second number of teeth is 42. The third rear sprocket 450C has a third number of teeth. The third number of teeth is 36. The fourth rear sprocket 450D has a fourth number of teeth. The fourth number of teeth is 32. The fifth rear sprocket 450E has a fifth number of teeth. The fifth number of teeth is 28. The sixth rear sprocket 450F has a sixth number of teeth. The sixth number of teeth is 24. The seventh rear sprocket 450G has a seventh number of teeth. The seventh number of teeth is 21. The eighth rear sprocket 450H has an eighth number of teeth. The eighth number of teeth is 18. The ninth rear sprocket 450I has a ninth number of teeth. The ninth tooth count is 16. The tenth rear sprocket 450J has a tenth tooth count. The tenth tooth count is 14. The eleventh rear sprocket 450K has an eleventh tooth count. The eleventh tooth count is twelve.

[0118] The twelfth rear sprocket 54I has a twelfth number of teeth (an example of a first number of teeth). The twelfth number of teeth is less than or equal to ten. For example, in the embodiment, the twelfth number of teeth is ten, which is the smallest number of teeth. Other embodiments (a) In the first to fifth embodiments, the description was provided for an example in which the present invention is applied to a road-type bicycle. Instead of this bicycle, the present invention can also be applied to a mountain bike and / or a city bike, etc. (b) In the first to fifth embodiments, the description has been provided for an example of the case where a plurality of rear sprockets are attached to the first tubular member 41 and one, two, or three of the rear sprockets are arranged on the second tubular member 43. The numbers of the rear sprockets arranged on the first tubular member 41 and the second tubular member 43 are not limited to the first to fourth embodiments and can be optionally adjusted. (c) In the first to fifth embodiments, the second tubular member 43 is provided separately from the first tubular member 41. Instead, the second tubular member 43 may be formed integrally with the first tubular member 41. (d) In the first to fifth embodiments, the description was given for an example in which the front sprocket assembly 27b has two front sprockets. The number of front sprockets is not limited to the first to fifth embodiments, but can be optionally adjusted, such as one sprocket or three sprockets. (e) Although the first sprockets 50A, 150A, 250A, 350A, and 450A, as illustrated in the first to fifth embodiments, respectively include shift assist protrusions 54, 154, 254, and 354, the shift assist protrusions may be omitted from the first sprocket in the first, fourth, and fifth embodiments because the difference between the first tooth count and the tooth count of the adjacent sprockets is not large compared to the second and third embodiments. The shift assist protrusions 154 and 254 may also be omitted from the first sprockets 150A and 250A as needed. (f) Although the shift assist protrusions 54, 154, 254 and 354 are provided to the first sprocket 50A, 150A, 250A and 350A only in the first to fifth embodiments, such shift assist protrusion 54, 154, 254 and 354 may also be provided for the other sprockets as needed.

Claims

[1] A bicycle multiple sprocket assembly (50) having a rotational center axis (C; 35) and configured to be mounted to a bicycle hub assembly, the bicycle multiple sprocket assembly (50) comprising: a first sprocket (50A; 150A; 250A; 350A; 450A) having a first number of teeth that is less than or equal to ten; a second sprocket (50B; 150B; 250B; 350B; 450B) having a second number of teeth greater than or equal to fifty; a third sprocket (50C; 150C; 250C; 350C; 450C) having a third number of teeth which is twelve, wherein the third sprocket (50C; 150C; 250C; 350C; 450C) is positioned between the first sprocket (50A; 150A; 250A; 350A; 450A) and the second sprocket (50B; 150B; 250B; 350B; 450B) in an axial direction parallel to the rotational center axis; a fourth sprocket (50D; 150D; 250D; 350D; 450D) having a fourth number of teeth, wherein the fourth sprocket (50D; 150D; 250D; 350D; 450D) is positioned between the second sprocket (50B; 150B; 250B; 350B; 450B) and the third sprocket (50C; 150C; 250C; 350C; 450C) in the axial direction; a fifth sprocket (50E; 150E; 250E; 350E; 450E) having a fifth number of teeth which is fourteen, wherein the fifth sprocket (50E; 150E; 250E; 350E; 450E) is positioned between the third sprocket (50C; 150C; 250C; 350C; 450C) and the fourth sprocket (50D; 150D; 250D; 350D; 450D) in the axial direction; a sixth sprocket (50F; 150F; 250F; 350F; 450F) having a sixth number of teeth, wherein the sixth sprocket (50F; 150F; 250F; 350F; 450F) is positioned between the fourth sprocket (50D; 150D; 250D; 350D; 450D) and the fifth sprocket (50E; 150E; 250E; 350E; 450E) in the axial direction; a seventh sprocket (50G; 150G; 250G; 350G; 450G) having a seventh number of teeth which is sixteen, wherein the seventh sprocket (50G; 150G; 250G; 350G; 450G) is positioned between the fifth sprocket (50E; 150E; 250E; 350E; 450E) and the sixth sprocket (50F; 150F; 250F; 350F; 450F) in the axial direction; an eighth sprocket (50H; 150H; 250H; 350H; 450H) having an eighth number of teeth, wherein the eighth sprocket (50H; 150H; 250H; 350H; 450H) is positioned between the sixth sprocket (50F; 150F; 250F; 350F; 450F) and the seventh sprocket (50G; 150G; 250G; 350G; 450G) in the axial direction; a ninth sprocket (50I; 150I; 250I; 350I; 450I) having a ninth number of teeth which is eighteen, wherein the ninth sprocket (50I; 150I; 250I; 350I; 450I) is positioned between the seventh sprocket (50G; 150G; 250G; 350G; 450G) and the eighth sprocket (50H; 150H; 250H; 350H; 450H) in the axial direction; a tenth sprocket (50J; 150J; 250J; 350J; 450J) having a tenth number of teeth which is twenty-eight, wherein the tenth sprocket is positioned between the eighth sprocket (50H; 150H; 250H; 350H; 450H) and the ninth sprocket (50I; 150I; 250I; 350I; 450I) in the axial direction; an eleventh sprocket (50K; 150K; 250K; 350K; 450K) having an eleventh tooth number of twenty-one, wherein the eleventh sprocket (50K; 150K; 250K; 350K; 450K) is positioned between the ninth sprocket (50I; 150I; 250I; 350I; 450I) and the tenth sprocket (50J; 150J; 250J; 350J; 450J) in the axial direction; and a twelfth sprocket (50L; 150L; 250L; 350L; 450L) having a twelfth tooth number of twenty-four, wherein the twelfth sprocket (50L; 150L; 250L; 350L; 450L) is positioned between the tenth sprocket (50J; 150J; 250J; 350J; 450J) and the eleventh sprocket (50K; 150K; 250K; 350K; 450K) in the axial direction; and wherein the total sprocket number is twelve. [2] A bicycle multiple sprocket assembly (50) having a rotational center axis and configured to be mounted to a bicycle hub assembly, the bicycle multiple sprocket assembly (50) comprising: a first sprocket (50A; 150A; 250A; 350A; 450A) having a first number of teeth less than or equal to ten; a second sprocket (50B; 150B; 250B; 350B; 450B) having a second number of teeth greater than or equal to fifty; and further comprehensive: ten additional sprockets positioned between the first sprocket (50A; 150A; 250A; 350A; 450A) and the second sprocket (50B; 150B; 250B; 350B; 450B) in an axial direction parallel to the rotational center axis (C; 35), and wherein the total number of sprockets is twelve. [3] Bicycle multiple sprocket assembly (50) according to one of claims 1 to 2, wherein the second sprocket (50B; 150B; 250B; 350B; 450B) includes at least one shift assist projection (54; 154; 254; 354). [4] Bicycle multiple sprocket assembly (50) according to one of claims 1 to 3, wherein the first sprocket (50A; 150A; 250A; 350A; 450A) is configured to be mounted to the bicycle hub assembly via a mounting adapter (43). [5] A bicycle multiple sprocket assembly (50) according to any one of claims 1 to 4, wherein the axial thickness of each of the first sprocket (50A; 150A; 250A; 350A; 450A), the second sprocket (50B; 150B; 250B; 350B; 450B) and the additional sprockets is 1.6 mm. [6] A bicycle multiple sprocket assembly (50) according to claim 1, wherein the axial length of each space between the axially adjacent sprockets is 2.2 mm. [7] A bicycle multiple sprocket assembly according to claim 2, wherein the total axial length between the first sprocket (50A; 150A; 250A; 350A; 450A) and the second sprocket (50B; 150B; 250B; 350B; 450B) is 43.4 mm. [8] A bicycle multiple sprocket assembly (50) according to claim 1 or 2, wherein the fourth tooth number is forty-two; the sixth number of teeth thirty-six; and the eighth number of teeth is thirty-two. [9] A bicycle multiple sprocket assembly (50) according to claim 3, wherein the at least one shift assist projection (54; 154; 254; 354) catches a chain in front of the sprocket teeth of the second sprocket (50B; 150B; 250B; 350B; 450B) when a rear derailleur moves the chain to the second sprocket (50B; 150B; 250B; 350B; 450B). [10] Drive section for a bicycle, the drive section comprising: a crank arrangement (27); a rear hub assembly (29); and the bicycle multiple sprocket assembly (50) according to one of claims 1 to 9.

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