Human-powered vehicle crank arm, human-powered vehicle crank assembly, and human-powered vehicle front sprocket

Abstract

To provide a human-powered vehicle crank arm, a human-powered vehicle crank assembly, and a human-powered vehicle front sprocket that are excellent in balance between weight reduction and fixing force.SOLUTION: A crank arm is provided with an arm body that includes: a crank bearing receiving opening having a center axis for receiving a crank bearing; a pedal bearing receiving opening having a center axis for receiving a pedal bearing; a first arm mounting hole; a second arm mounting hole arranged adjacent to the first arm mounting hole without another arm mounting hole disposed between the first arm mounting hole and the second arm mounting hole in a circumferential direction of the arm; a third arm mounting hole arranged adjacent to the second arm mounting hole without another arm mounting hole disposed between the second arm mounting hole and the third arm mounting hole in the circumferential direction of the arm; and a fourth arm mounting hole arranged adjacent to both the first arm mounting hole and the third arm mounting hole without another arm mounting hole disposed between the first arm mounting hole and the fourth arm mounting hole and between the third arm mounting hole and the fourth arm mounting hole in the circumferential direction of the arm.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a crank arm for a human-powered vehicle, a crank assembly for a human-powered vehicle, and a front sprocket for a human-powered vehicle. [Background technology]

[0002] The crank arm for a human-powered vehicle in Patent Document 1 is attached to a front sprocket by eight bolts aligned in the circumferential direction about the central axis of rotation of the crank arm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 10,343,745 Summary of the Invention [Problem to be solved by the invention]

[0004] One object of the present disclosure is to provide a crank arm for a human-powered vehicle, a crank assembly for a human-powered vehicle, and a front sprocket for a human-powered vehicle that have an excellent balance between lightweight and fixing force. [Means for solving the problem]

[0005] A crank arm according to a first aspect of the present disclosure is a crank arm for a human-powered vehicle, the crank arm having an arm rotation central axis that defines an arm circumferential direction, the crank arm being configured to receive a crank shaft in an assembled state of a crank assembly including the crank arm, the crank arm having a crank bearing inlet central axis that is coaxial with the arm rotation central axis of the crank arm, a pedal bearing inlet opening configured to receive a pedal shaft in the assembled state, the pedal bearing inlet central axis, a first arm mounting hole, and arranged adjacent to the first arm mounting hole in the arm circumferential direction with no other arm mounting hole between them. the arm body having a second arm mounting hole disposed adjacent to the second arm mounting hole in the arm circumferential direction without any other arm mounting holes intervening between the second arm mounting hole and the fourth arm mounting hole in the arm circumferential direction between the first arm mounting hole and the third arm mounting hole without any other arm mounting holes intervening, and each of the first arm mounting hole, the second arm mounting hole, the third arm mounting hole and the fourth arm mounting hole are configured to receive a fastener so that a sprocket body can be attached to the crank arm. According to the crank arm of the first aspect, the arm body has only four arm attachment holes, and therefore, an excellent balance between weight reduction and fixing strength is achieved.

[0006] In the crank arm of a second aspect according to the first aspect of the present disclosure, the arm body has an arm reference line passing through the crank bearing-in central axis and the pedal bearing-in central axis, the arm reference line being configured to be a boundary between a first arm region and a second arm region, the first arm mounting hole and the fourth arm mounting hole are arranged in the first arm region, the second arm mounting hole and the third arm mounting hole are arranged in the second arm region, the first arm mounting hole, the second arm mounting hole, the third arm mounting hole and the fourth arm mounting hole are arranged to surround the crank bearing-in opening in the arm circumferential direction, the third arm mounting hole and the fourth arm mounting hole are arranged closer to the pedal bearing-in opening than the first arm mounting hole and the second arm mounting hole, and a first circumferential arm distance is a second circumferential arm distance is defined by the distance between the second arm mounting hole and the third arm mounting hole in the arm circumferential direction, a third circumferential arm distance is defined by the distance between the third arm mounting hole and the fourth arm mounting hole in the arm circumferential direction, and a fourth circumferential arm distance is defined by the distance between the fourth arm mounting hole and the first arm mounting hole in the arm circumferential direction, and at least one of the first circumferential arm distance, the second circumferential arm distance, the third circumferential arm distance, and the fourth circumferential arm distance is different from at least one other of the first circumferential arm distance, the second circumferential arm distance, the third circumferential arm distance, and the fourth circumferential arm distance. According to the crank arm of the second side surface, since the arm body has only four arm attachment holes, it has an excellent balance between weight reduction and fixing strength.

[0007] In a third aspect crank arm according to the second aspect of the present disclosure, at least one of the second circumferential arm distance and the fourth circumferential arm distance is longer than at least one of the first circumferential arm distance and the third circumferential arm distance. The crank arm of the third aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0008] In a fourth aspect crank arm according to the third aspect of the present disclosure, each of the second circumferential arm distance and the fourth circumferential arm distance is longer than each of the first circumferential arm distance and the third circumferential arm distance. The crank arm of the fourth aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0009] In a fifth aspect of the crank arm according to the fourth aspect of the present disclosure, the first circumferential arm distance is equal to the third circumferential arm distance. The crank arm of the fifth aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0010] In a sixth aspect of the crank arm according to the fourth or fifth aspect of the present disclosure, the second circumferential arm distance is equal to the fourth circumferential arm distance. The crank arm of the sixth aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0011] In a crank arm of a seventh aspect according to any one of the fourth to sixth aspects of the present disclosure, each of the second circumferential arm distance and the fourth circumferential arm distance is greater than or equal to twice each of the first circumferential arm distance and the third circumferential arm distance. The crank arm of the seventh aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0012] In the crank arm of an eighth aspect according to the seventh aspect of the present disclosure, each of the second circumferential arm distance and the fourth circumferential arm distance is greater than or equal to three times each of the first circumferential arm distance and the third circumferential arm distance. The crank arm of the eighth aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0013] In a crank arm of a ninth aspect according to any one of the fourth to eighth aspects of the present disclosure, each of the second circumferential arm distance and the fourth circumferential arm distance is less than or equal to eight times each of the first circumferential arm distance and the third circumferential arm distance. The crank arm of the ninth aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0014] In a crank arm of a tenth aspect according to any one of the first to ninth aspects of the present disclosure, each of the first arm mounting hole, the second arm mounting hole, the third arm mounting hole, and the fourth arm mounting hole is configured to be threadedly engaged with the fastener. According to the crank arm of the tenth aspect, the crank assembly can be securely assembled by screwing the arm attachment hole into the fastener.

[0015] In a crank arm of an eleventh aspect according to any one of the first to eighth aspects of the present disclosure, the arm body includes a plurality of arm spline teeth arranged around the crank bearing receiving opening in the arm circumferential direction and configured to couple with the sprocket body to transmit torque. The crank arm on the eleventh side allows efficient torque transmission.

[0016] In the crank arm of a twelfth aspect in accordance with an eleventh aspect of the present disclosure, the multiple arm spline teeth include at least one first arm spline tooth arranged between the first arm mounting hole and the fourth arm mounting hole in the arm circumferential direction, and at least one second arm spline tooth arranged between the second arm mounting hole and the third arm mounting hole in the arm circumferential direction. According to the crank arm on the twelfth side surface, the strength of the portion that transmits torque is excellent.

[0017] In a crank arm of a thirteenth aspect in accordance with the twelfth aspect of the present disclosure, the arm body has an arm reference line passing through the crank bearing-received central axis and the pedal bearing-received central axis, the at least one first arm spline tooth includes a plurality of first arm spline teeth, and the at least one second arm spline tooth includes a plurality of second arm spline teeth. The crank arm on the thirteenth side further improves the strength of the portion that transmits torque.

[0018] In a crank arm of a 14th side according to any one of the first to 13th sides of the present disclosure, the first arm mounting hole, the second arm mounting hole, the third arm mounting hole, and the fourth arm mounting hole are symmetrically arranged with respect to at least one of the arm reference line and the arm rotation central axis. The crank arm of the fourteenth aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0019] A crank assembly according to a fifteenth aspect of the present disclosure is a crank assembly for a human-powered vehicle, the crank assembly having an assembly rotation central axis that coincides with the arm rotation central axis of the crank arm in the assembled state, the assembly rotation central axis defining an assembly circumferential direction, the crank assembly including the crank arm on any one of a first side surface to a fourteenth side surface, and the sprocket body, the sprocket body including a first sprocket mounting hole aligned with the first arm mounting hole of the crank arm in the assembled state, and a first sprocket mounting hole aligned with the first arm mounting hole of the crank arm in the assembled state, the first sprocket mounting hole aligned with the first arm mounting hole of the crank arm in the assembled state, and the first sprocket mounting hole aligned with the first arm mounting hole of the crank arm in the assembled state. the crank arm in the assembled state, a second sprocket mounting hole that aligns with the second arm mounting hole of the crank arm in the erected state, a third sprocket mounting hole that aligns with the third arm mounting hole of the crank arm in the assembled state, and a fourth sprocket mounting hole that aligns with the fourth arm mounting hole of the crank arm in the assembled state, and each of the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole and the fourth sprocket mounting hole are configured to receive a fastener so that the sprocket body is attached to the crank arm. According to the crank assembly of the fifteenth aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0020] In a crank assembly of a sixteenth aspect according to a fifteenth aspect of the present disclosure, the second sprocket mounting hole is arranged adjacent to the first sprocket mounting hole in the assembly circumferential direction between the first sprocket mounting hole and the second sprocket mounting hole without any other sprocket mounting holes configured to receive a fastener therebetween, the third sprocket mounting hole is arranged adjacent to the second sprocket mounting hole in the assembly circumferential direction between the second sprocket mounting hole and the third sprocket mounting hole without any other sprocket mounting holes configured to receive a fastener therebetween, and the fourth sprocket mounting hole is arranged adjacent to each of the first sprocket mounting hole and the third sprocket mounting hole in the assembly circumferential direction between the first sprocket mounting hole and the fourth sprocket mounting hole and between the third sprocket mounting hole and the fourth sprocket mounting hole, respectively, without any other sprocket mounting holes configured to receive a fastener therebetween. According to the crank assembly of the sixteenth aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0021] In a crank assembly of a 17th aspect according to the 15th or 16th aspect of the present disclosure, the arm body has an arm reference line passing through the crank bearing inlet central axis and the pedal bearing inlet central axis, the sprocket body has a sprocket reference line corresponding to the arm reference line of the crank arm in the assembled state, the sprocket reference line is configured to be a boundary between a first sprocket area and a second sprocket area, the first sprocket mounting hole and the fourth sprocket mounting hole are arranged in the first sprocket area, and the second sprocket mounting hole and the third sprocket mounting hole are arranged in the second sprocket area. According to the crank assembly of the seventeenth aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0022] In a crank assembly of an 18th aspect according to any one of the 15th to 17th aspects of the present disclosure, the sprocket body has a crank arm receiving opening configured to receive the crank arm in the assembled state, and the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole, and the fourth sprocket mounting hole are arranged around the crank arm receiving opening. According to the crank assembly of the eighteenth aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0023] In a crank assembly of a nineteenth aspect according to the eighteenth aspect of the present disclosure, the sprocket body includes a plurality of sprocket spline teeth arranged around the crank arm receiving opening and configured to couple to the crank arm in a torque transmitting manner. According to the crank assembly of the nineteenth aspect, torque can be transmitted efficiently.

[0024] In a crank assembly of a 20th aspect according to a 19th aspect of the present disclosure, the plurality of sprocket spline teeth include at least one first sprocket spline tooth arranged between the first sprocket mounting hole and the fourth sprocket mounting hole in the assembly circumferential direction, and at least one second sprocket spline tooth arranged between the second sprocket mounting hole and the third sprocket mounting hole in the assembly circumferential direction. According to the crank assembly of the twentieth aspect, the strength of the portion that transmits torque is excellent.

[0025] In a crank assembly of a twenty-first aspect according to a twentieth aspect of the present disclosure, the at least one first sprocket spline tooth includes a plurality of first sprocket spline teeth, and the at least one second sprocket spline tooth includes a plurality of second sprocket spline teeth. According to the crank assembly of the twenty-first aspect, the strength of the portion that transmits torque is further improved.

[0026] In a crank assembly of a 22nd side according to any one of the 15th to 21st sides of the present disclosure, the third sprocket mounting hole and the fourth sprocket mounting hole are positioned closer to the pedal bearing receiving opening than the first sprocket mounting hole and the second sprocket mounting hole in the assembled state. According to the crank assembly of the twenty-second aspect, the loosening of the fastener is suppressed excellently.

[0027] In a crank assembly of a twenty-third aspect according to any one of the fifteenth to twenty-second aspects of the present disclosure, a first circumferential sprocket distance is defined by a distance between the first sprocket mounting hole and the second sprocket mounting hole in the assembly circumferential direction, a second circumferential sprocket distance is defined by a distance between the second sprocket mounting hole and the third sprocket mounting hole in the assembly circumferential direction, a third circumferential sprocket distance is defined by a distance between the third sprocket mounting hole and the fourth sprocket mounting hole in the assembly circumferential direction, and a fourth circumferential sprocket distance is defined by a distance between the fourth sprocket mounting hole and the first sprocket mounting hole in the assembly circumferential direction, and at least one of the first circumferential sprocket distance, the second circumferential sprocket distance, the third circumferential sprocket distance, and the fourth circumferential sprocket distance is different from at least one other of the first circumferential sprocket distance, the second circumferential sprocket distance, the third circumferential sprocket distance, and the fourth circumferential sprocket distance. According to the crank assembly of the twenty-third aspect, the sprocket body has only four sprocket mounting holes, so that it has an excellent balance between weight reduction and fixing force.

[0028] In the crank assembly of a twenty-fourth aspect according to a twenty-third aspect of the present disclosure, at least one of the second circumferential sprocket distance and the fourth circumferential sprocket distance is longer than at least one of the first circumferential sprocket distance and the third circumferential sprocket distance. According to the crank assembly of the twenty-fourth aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0029] In the crank assembly of a twenty-fifth aspect according to the twenty-fourth aspect of the present disclosure, each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is longer than each of the first circumferential sprocket distance and the third circumferential sprocket distance. According to the crank assembly of the twenty-fifth aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0030] In a crank assembly of a 26th aspect according to any one of the 15th to 25th aspects of the present disclosure, the sprocket body includes one of a plurality of sprocket teeth formed integrally with the sprocket body and a sprocket tooth ring including a plurality of sprocket teeth and separate from the sprocket body. The crank assembly of the twenty-sixth aspect provides excellent drive efficiency.

[0031] In the crank assembly of the 27th aspect according to the 15th aspect of the present disclosure, the crank assembly further comprises a first fastener configured to be received in the first sprocket mounting hole and the first arm mounting hole, a second fastener configured to be received in the second sprocket mounting hole and the second arm mounting hole, a third fastener configured to be received in the third sprocket mounting hole and the third arm mounting hole, and a fourth fastener configured to be received in the fourth sprocket mounting hole and the fourth arm mounting hole, wherein the first fastener, the second fastener, the third fastener, and the fourth fastener are configured to secure the sprocket body to the crank arm. According to the crank assembly of the twenty-seventh aspect, the fastener is prevented from loosening, and the strength of the portion that transmits torque is excellent.

[0032] In the crank assembly of a 28th aspect according to the 27th aspect of the present disclosure, the crank assembly further includes a first spacer arranged on the first fastener so as to adjust a position of the sprocket body relative to the crank arm in the axial direction relative to the assembly rotation central axis, a second spacer arranged on the second fastener so as to adjust a position of the sprocket body relative to the crank arm in the axial direction relative to the assembly rotation central axis, a third spacer arranged on the third fastener so as to adjust a position of the sprocket body relative to the crank arm in the axial direction relative to the assembly rotation central axis, and a fourth spacer arranged on the fourth fastener so as to adjust a position of the sprocket body relative to the crank arm in the axial direction relative to the assembly rotation central axis. According to the crank assembly of the twenty-eighth aspect, the chain line of the chain applied to the front sprocket and the rear sprocket can be efficiently adjusted.

[0033] A front sprocket according to a twenty-ninth aspect of the present disclosure is a front sprocket for a human-powered vehicle, the front sprocket having a sprocket rotation central axis defining a sprocket circumferential direction, the front sprocket including a sprocket body, the sprocket body including a crank arm receiving opening configured to receive the crank arm in an assembled state of a crank assembly including the front sprocket and the crank arm, a first sprocket mounting hole, a second sprocket mounting hole arranged adjacent to the first sprocket mounting hole in the sprocket circumferential direction with no other sprocket mounting hole between them, and a second sprocket mounting hole arranged adjacent to the first sprocket mounting hole in the sprocket circumferential direction. the sprocket body is attached to the crank arm. The sprocket body has a third sprocket mounting hole arranged adjacent to the second sprocket mounting hole without any other sprocket mounting holes between it and the first sprocket mounting hole and a fourth sprocket mounting hole arranged adjacent to each of the first sprocket mounting hole and the third sprocket mounting hole in the circumferential direction of the sprocket, between the first sprocket mounting hole and the third sprocket mounting hole, respectively, without any other sprocket mounting holes between them, and each of the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole and the fourth sprocket mounting hole is configured to receive a fastener so that the sprocket body is attached to the crank arm. According to the front sprocket of the twenty-ninth aspect, the sprocket body has only four sprocket mounting holes, so that it has an excellent balance between weight reduction and fixing force.

[0034] In a front sprocket of a 30th aspect according to a 29th aspect of the present disclosure, the sprocket body has a sprocket reference line that corresponds to an arm reference line of the crank arm in the assembled state, the arm reference line of the crank arm passes through a crank bearing inlet central axis of a crank bearing inlet opening of the crank arm and a pedal bearing inlet central axis of a pedal bearing inlet opening of the crank arm, the sprocket reference line is configured to be a boundary between a first sprocket region and a second sprocket region, the first sprocket mounting hole and the fourth sprocket mounting hole are disposed in the first sprocket region, the second sprocket mounting hole and the third sprocket mounting hole are disposed in the second sprocket region, the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole and the fourth sprocket mounting hole are disposed around the crank arm receiving opening, and the third sprocket mounting hole and the fourth sprocket mounting hole are configured to be spaced apart from the first sprocket mounting hole and the second sprocket mounting hole in the assembled state. a first circumferential sprocket distance is defined by the distance between the first sprocket mounting hole and the second sprocket mounting hole in the sprocket circumferential direction, a second circumferential sprocket distance is defined by the distance between the second sprocket mounting hole and the third sprocket mounting hole in the sprocket circumferential direction, a third circumferential sprocket distance is defined by the distance between the third sprocket mounting hole and the fourth sprocket mounting hole in the sprocket circumferential direction, and a fourth circumferential sprocket distance is defined by the distance between the fourth sprocket mounting hole and the first sprocket mounting hole in the sprocket circumferential direction, and at least one of the first circumferential sprocket distance, the second circumferential sprocket distance, the third sprocket distance, and the fourth circumferential sprocket distance is different from at least one other of the first circumferential sprocket distance, the second circumferential sprocket distance, the third sprocket distance, and the fourth circumferential sprocket distance. According to the front sprocket of the thirtieth side face, the sprocket body has only four sprocket mounting holes, so that it has an excellent balance between weight reduction and fixing force.

[0035] In a front sprocket of a thirty-first aspect in accordance with a thirty-first aspect of the present disclosure, at least one of the second circumferential sprocket distance and the fourth circumferential sprocket distance is longer than at least one of the first circumferential sprocket distance and the third circumferential sprocket distance. The front sprocket according to the thirty-first aspect is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0036] In a front sprocket of a thirty-second aspect according to a thirty-first aspect of the present disclosure, each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is longer than each of the first circumferential sprocket distance and the third circumferential sprocket distance. The front sprocket according to the thirty-second side face is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0037] In a front sprocket of a thirty-third aspect according to a thirty-second aspect of the present disclosure, the first circumferential sprocket distance is equal to the third circumferential sprocket distance. The front sprocket having the 33rd side surface is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0038] In a front sprocket of a thirty-fourth aspect according to the thirty-second or thirty-third aspect of the present disclosure, the second circumferential sprocket distance is equal to the fourth circumferential sprocket distance. According to the front sprocket of the 34th side surface, each of the four sprocket mounting holes can be disposed at a position that allows the crank assembly to be securely assembled in an assembled state of the crank assembly.

[0039] In a front sprocket of a thirty-fifth aspect according to any one of the thirty-second to thirty-fourth aspects of the present disclosure, each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than or equal to twice each of the first circumferential sprocket distance and the third circumferential sprocket distance. The front sprocket of the 35th side face is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0040] In a front sprocket of a 36th side according to any one of the 32nd to 34th sides of the present disclosure, each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than or equal to three times each of the first circumferential sprocket distance and the third circumferential sprocket distance. The front sprocket according to the thirty-sixth side face is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0041] In a front sprocket of a 37th side according to any one of the 29th to 36th sides of the present disclosure, the sprocket body includes a plurality of sprocket spline teeth arranged around the crank arm receiving opening and configured to couple to the crank arm in a torque transmitting manner. The front sprocket on the 37th side allows for efficient torque transmission.

[0042] In a front sprocket of a thirty-eighth aspect in accordance with the thirty-seventh aspect of the present disclosure, the plurality of sprocket spline teeth include at least one first sprocket spline tooth arranged between the first sprocket mounting hole and the fourth sprocket mounting hole in the circumferential direction of the sprocket, and at least one second sprocket spline tooth arranged between the second sprocket mounting hole and the third sprocket mounting hole in the circumferential direction of the sprocket. The front sprocket on the 38th side provides excellent strength in the portion that transmits torque.

[0043] In a front sprocket of a thirty-ninth aspect in accordance with a thirty-eighth aspect of the present disclosure, the at least one first sprocket spline tooth includes a plurality of first sprocket spline teeth, and the at least one second sprocket spline tooth includes a plurality of second sprocket spline teeth. The front sprocket on the 39th side further improves the strength of the portion that transmits torque.

[0044] In a front sprocket of a fortieth side according to any one of the twenty-ninth to thirty-ninth sides of the present disclosure, the sprocket body has a sprocket reference line which corresponds to an arm reference line of the crank arm in the assembled state, the arm reference line of the crank arm passes through a crank bearing inlet central axis of a crank bearing inlet opening of the crank arm and a pedal bearing inlet central axis of a pedal bearing inlet opening of the crank arm, and the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole and the fourth sprocket mounting hole are arranged symmetrically with respect to at least one of the sprocket reference line and the sprocket rotation central axis. The front sprocket having the fortieth side surface is excellent in preventing the fastener from loosening and in strength of the portion that transmits torque.

[0045] In a front sprocket of a 41st aspect according to any one of the 29th to 40th aspects of the present disclosure, the sprocket body includes one of a plurality of sprocket teeth formed integrally with the sprocket body and a sprocket tooth ring including a plurality of sprocket teeth and separate from the sprocket body. According to the front sprocket of the forty-first aspect, the drive efficiency of the crank assembly including the front sprocket is excellent. Effect of the Invention

[0046] The crank arm for a human-powered vehicle, the crank assembly for a human-powered vehicle, and the front sprocket for a human-powered vehicle disclosed herein have an excellent balance between lightweight and fixing force. [Brief description of the drawings]

[0047] [Figure 1] FIG. 2 is a plan view of a crank assembly for a human-powered vehicle including a crank arm for a human-powered vehicle and a front sprocket for a human-powered vehicle according to an embodiment. [Diagram 2] FIG. 2 is a side view of a crank assembly for the human powered vehicle of FIG. 1. [Diagram 3] 2 is a side view of the crank arm for the human-powered vehicle and the front sprocket for the human-powered vehicle of FIG. 1, as viewed from the inside. [Figure 4] FIG. 2 is a side view of a crank arm for the human-powered vehicle of FIG. 1. [Diagram 5] FIG. 5 is an enlarged side view of a portion of FIG. [Figure 6] FIG. 2 is a side view of a front sprocket for the human-powered vehicle of FIG. 1. [Figure 7] 3 is a cross-sectional view taken along line D7-D7 in FIG. 2. [Figure 8] FIG. 2 is a cross-sectional view of a crank assembly for a human-powered vehicle with a spacer. [Figure 9] FIG. 9 is a side view of the spacer of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] <Embodiment> 1 to 9, a crank assembly 20 for a human powered vehicle is described, which includes a crank arm 30 for a human powered vehicle and a front sprocket 60 for a human powered vehicle.

[0049] A human-powered vehicle is a vehicle that has at least one wheel and can be driven at least by human driving force. Human-powered vehicles include various types of bicycles, such as mountain bikes, road bikes, city bikes, cargo bikes, hand bikes, and recumbents. The number of wheels that a human-powered vehicle has is not limited. Human-powered vehicles also include, for example, one-wheeled vehicles and vehicles with two or more wheels. Human-powered vehicles are not limited to vehicles that can be driven only by human driving force. Human-powered vehicles include E-bikes that use not only human driving force but also the driving force of an electric motor for propulsion. E-bikes include electrically assisted bicycles whose propulsion is assisted by an electric motor. Hereinafter, in each embodiment, the human-powered vehicle will be described as a bicycle.

[0050] As shown in FIG. 1, the human-powered vehicle 10 includes a crank assembly 20 for a human-powered vehicle. The crank assembly 20 for a human-powered vehicle includes a crank arm 30 for a human-powered vehicle. A crank shaft 22 and a pedal shaft are attached to the crank arm 30. The crank arm 30 is attached to one end of the crank shaft 22. A crank arm 24 separate from the crank arm 30 is attached to the other end of the crank shaft 22. The crank arm 30 is attached to at least one of a sprocket body 50 and a front sprocket 60 via a fastener 26. A human-powered driving force input to the pedal of the human-powered vehicle 10 is transmitted to the front sprocket 60 via the crank arm 30 and the crank shaft 22. The crank arm 30 of this embodiment is configured to rotate integrally with the crank shaft 22 and the front sprocket 60.

[0051] As shown in Figs. 2, 4, and 5, a crank arm 30 for a human-powered vehicle has an arm rotation central axis 30C that defines an arm circumferential direction DAR. The crank arm 30 includes an arm body 32. The arm body 32 has a crank bearing receiving opening 34, a pedal bearing receiving opening 36, a first arm mounting hole 38A, a second arm mounting hole 38B, a third arm mounting hole 38C, and a fourth arm mounting hole 38D. The crank bearing receiving opening 34 is configured to receive the crank shaft 22 in an assembled state of the crank assembly 20 including the crank arm 30, and has a crank bearing receiving central axis 34C that is coaxial with the arm rotation central axis 30C of the crank arm 30. The pedal bearing receiving opening 36 is configured to receive the pedal shaft in an assembled state, and has a pedal bearing receiving central axis 36C. The second arm mounting hole 38B is disposed adjacent to the first arm mounting hole 38A in the arm circumferential direction DAR without any other arm mounting holes between them. The third arm mounting hole 38C is disposed adjacent to the second arm mounting hole 38B in the arm circumferential direction DAR without any other arm mounting holes between them. The fourth arm mounting hole 38D is disposed adjacent to each of the first arm mounting hole 38A and the third arm mounting hole 38C in the arm circumferential direction DAR between them and the first arm mounting hole 38A and between them and the third arm mounting hole 38C without any other arm mounting holes between them. Each of the first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D is configured to receive a fastener 26 so that the sprocket body 50 can be attached to the crank arm 30.

[0052] As shown in FIGS. 3 and 7, first arm mounting hole 38A, second arm mounting hole 38B, third arm mounting hole 38C, and fourth arm mounting hole 38D are each configured to receive fastener 26, for example.

[0053] Each of the first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D is configured to be threadedly coupled with a fastener 26. The fastener 26 is, for example, a bolt. Each of the first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D includes, for example, a female thread that engages with the bolt.

[0054] 4 and 5, the crank arm 30 of this embodiment has only four arm mounting holes 38A, 38B, 38C, and 38D as arm mounting holes for mounting the crank arm 30 and the front sprocket 60. The first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D are, for example, arranged concentrically on the arm body 32. The first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D have, for example, the same inner diameters.

[0055] The arm body 32 has an arm reference line CX passing through the crank bearing entrance central axis 34C and the pedal bearing entrance central axis 36C. The arm reference line CX is configured to be the boundary between the first arm region RA1 and the second arm region RA2. The first arm mounting hole 38A and the fourth arm mounting hole 38D are disposed in the first arm region RA1. The second arm mounting hole 38B and the third arm mounting hole 38C are disposed in the second arm region RA2. The first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D are disposed to surround the crank bearing entrance opening 34 in the arm circumferential direction DAR. The third arm mounting hole 38C and the fourth arm mounting hole 38D are disposed closer to the pedal bearing entrance opening 36 than the first arm mounting hole 38A and the second arm mounting hole 38B.

[0056] The first circumferential arm distance LA1 is defined by the distance between the first arm mounting hole 38A and the second arm mounting hole 38B in the arm circumferential direction DAR. The second circumferential arm distance LA2 is defined by the distance between the second arm mounting hole 38B and the third arm mounting hole 38C in the arm circumferential direction DAR. The third circumferential arm distance LA3 is defined by the distance between the third arm mounting hole 38C and the fourth arm mounting hole 38D in the arm circumferential direction DAR. The fourth circumferential arm distance LA4 is defined by the distance between the fourth arm mounting hole 38D and the first arm mounting hole 38A in the arm circumferential direction DAR. At least one of the first circumferential arm distance LA1, the second circumferential arm distance LA2, the third circumferential arm distance LA3, and the fourth circumferential arm distance LA4 is different from at least one of the other of the first circumferential arm distance LA1, the second circumferential arm distance LA2, the third circumferential arm distance LA3, and the fourth circumferential arm distance LA4.

[0057] The first circumferential arm distance LA1 is defined, for example, by the distance from the center of the first arm mounting hole 38A to the center of the second arm mounting hole 38B in the arm circumferential direction DAR. The second circumferential arm distance LA2 is defined, for example, by the distance from the center of the second arm mounting hole 38B to the center of the third arm mounting hole 38C in the arm circumferential direction DAR. The third circumferential arm distance LA3 is defined, for example, by the distance from the center of the third arm mounting hole 38C to the center of the fourth arm mounting hole 38D in the arm circumferential direction DAR. The fourth circumferential arm distance LA4 is defined, for example, by the distance from the center of the fourth arm mounting hole 38D to the center of the first arm mounting hole 38A in the arm circumferential direction DAR.

[0058] At least one of the second circumferential direction arm distance LA2 and the fourth circumferential direction arm distance LA4 is longer than at least one of the first circumferential direction arm distance LA1 and the third circumferential direction arm distance LA3, for example. Each of the second circumferential direction arm distance LA2 and the fourth circumferential direction arm distance LA4 is longer than each of the first circumferential direction arm distance LA1 and the third circumferential direction arm distance LA3, for example. Only one of the second circumferential direction arm distance LA2 and the fourth circumferential direction arm distance LA4 may be longer than each of the first circumferential direction arm distance LA1 and the third circumferential direction arm distance LA3.

[0059] The first circumferential direction arm distance LA1 is equal to the third circumferential direction arm distance LA3, for example. The second circumferential direction arm distance LA2 is equal to the fourth circumferential direction arm distance LA4, for example. The first circumferential direction arm distance LA1, the second circumferential direction arm distance LA2, the third circumferential direction arm distance LA3, and the fourth circumferential direction arm distance LA4 satisfy the relationship of LA1 = LA3 < LA2 = LA4, for example.

[0060] Each of the second circumferential direction arm distance LA2 and the fourth circumferential direction arm distance LA4 is, for example, more than twice each of the first circumferential direction arm distance LA1 and the third circumferential direction arm distance LA3. Each of the second circumferential direction arm distance LA2 and the fourth circumferential direction arm distance LA4 is, for example, more than three times each of the first circumferential direction arm distance LA1 and the third circumferential direction arm distance LA3. Each of the second circumferential direction arm distance LA2 and the fourth circumferential direction arm distance LA4 is, for example, not more than eight times each of the first circumferential direction arm distance LA1 and the third circumferential direction arm distance LA3.

[0061] The arm body 32 has an arm reference line CX passing through the crank bearing entry central axis 34C and the pedal bearing entry central axis 36C. The first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D are, for example, arranged symmetrically with respect to at least one of the arm reference line CX and the arm rotation central axis 30C. The first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D are, for example, arranged line-symmetrically with respect to the arm reference line CX. The first arm mounting hole 38A, the second arm mounting hole 38B, the third arm mounting hole 38C, and the fourth arm mounting hole 38D are, for example, arranged point-symmetrically with respect to the arm rotation central axis 30C. First arm mounting hole 38A, second arm mounting hole 38B, third arm mounting hole 38C, and fourth arm mounting hole 38D are arranged, for example, line-symmetrically with respect to arm reference line CX and point-symmetrically with respect to arm rotation central axis 30C.

[0062] The arm body 32 includes, for example, a plurality of arm spline teeth 40. The plurality of arm spline teeth 40 are arranged, for example, around the crank bearing receiving opening 34 in the arm circumferential direction DAR. The plurality of arm spline teeth 40 are configured to couple with a sprocket body 50, for example, to transmit torque.

[0063] The arm spline teeth 40 include, for example, at least one first arm spline tooth 40A and at least one second arm spline tooth 40B. The at least one first arm spline tooth 40A is, for example, disposed between the first arm mounting hole 38A and the fourth arm mounting hole 38D in the arm circumferential direction DAR. The at least one second arm spline tooth 40B is, for example, disposed between the second arm mounting hole 38B and the third arm mounting hole 38C in the arm circumferential direction DAR.

[0064] The at least one first arm spline tooth 40A includes, for example, a plurality of first arm spline teeth 40A. The at least one second arm spline tooth 40B includes, for example, a plurality of second arm spline teeth 40B. The number of the plurality of first arm spline teeth 40A is, for example, five. The number of the plurality of second arm spline teeth 40B is, for example, five. The numbers of the plurality of first arm spline teeth 40A and the plurality of second arm spline teeth 40B are not limited to the numbers exemplified in this embodiment.

[0065] At least one of the multiple arm spline teeth 40 may be disposed, for example, between the first arm mounting hole 38A and the second arm mounting hole 38B in the arm circumferential direction DAR. In this embodiment, the number of arm spline teeth 40 disposed between the first arm mounting hole 38A and the second arm mounting hole 38B in the arm circumferential direction DAR is, for example, 1. At least one of the multiple arm spline teeth 40 may be disposed, for example, between the third arm mounting hole 38C and the fourth arm mounting hole 38D in the arm circumferential direction DAR. In this embodiment, the number of arm spline teeth 40 disposed between the third arm mounting hole 38C and the fourth arm mounting hole 38D in the arm circumferential direction DAR is, for example, 1.

[0066] The arm spline teeth 40 may include, for example, at least one deformed tooth 40C. The deformed tooth 40C is, for example, disposed between the first arm mounting hole 38A and the second arm mounting hole 38B in the arm circumferential direction DAR. The deformed tooth 40C is, for example, disposed between the third arm mounting hole 38C and the fourth arm mounting hole 38D in the arm circumferential direction DAR.

[0067] 2 and 4, the crank assembly 20 for a human-powered vehicle has, in an assembled state, an assembly rotation central axis 20C that coincides with the arm rotation central axis 30C of the crank arm 30. The assembly rotation central axis 20C defines an assembly circumferential direction DCR. The crank assembly 20 includes the crank arm 30 and a sprocket body 50.

[0068] As shown in Fig. 6, a front sprocket 60 for a human-powered vehicle has a sprocket rotation center axis 60C that defines a sprocket circumferential direction DSR. The front sprocket 60 includes a sprocket body 50. As shown in Figs. 2 and 3, the sprocket circumferential direction DSR is equal to, for example, an assembly circumferential direction DCR in an assembled state. The sprocket circumferential direction DSR is equal to, for example, an arm circumferential direction DAR in an assembled state.

[0069] As shown in FIG. 6, the sprocket body 50 includes one of a plurality of sprocket teeth 50A formed integrally with the sprocket body 50 and a sprocket tooth ring including a plurality of sprocket teeth 50A and separate from the sprocket body 50. The sprocket body 50 in FIG. 1 to FIG. 9 includes a plurality of sprocket teeth 50A formed integrally with the sprocket body 50. When the sprocket body 50 includes a plurality of sprocket teeth 50A formed integrally with the sprocket body 50, the front sprocket 60 may be substantially the same as the sprocket body 50. When the sprocket body 50 includes a separate sprocket tooth ring having a plurality of sprocket teeth 50A, the front sprocket 60 is, for example, composed of the sprocket body 50 and the sprocket tooth ring. When the front sprocket 60 is composed of the sprocket body 50 and the sprocket tooth ring, for example, the sprocket tooth ring is attached to the outer periphery of the sprocket body 50. The sprocket tooth ring is attached to the sprocket body 50, for example, by bolts or rivets.

[0070] The sprocket body 50 has, for example, a first sprocket mounting hole 52A, a second sprocket mounting hole 52B, a third sprocket mounting hole 52C, and a fourth sprocket mounting hole 52D. The sprocket body 50 has, for example, a crank arm receiving opening 54 configured to receive the crank arm 30 in an assembled state of the crank assembly 20 including the front sprocket 60 and the crank arm 30, the first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D.

[0071] The first sprocket mounting hole 52A aligns with the first arm mounting hole 38A of the crank arm 30 shown in FIG. 5 in the assembled state. The second sprocket mounting hole 52B aligns with the second arm mounting hole 38B of the crank arm 30 shown in FIG. 5 in the assembled state. The third sprocket mounting hole 52C aligns with the third arm mounting hole 38C of the crank arm 30 shown in FIG. 5 in the assembled state. The fourth sprocket mounting hole 52D aligns with the fourth arm mounting hole 38D of the crank arm 30 shown in FIG. 5 in the assembled state. Each of the first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D is configured to receive a fastener 26 shown in FIG. 3 so that the sprocket body 50 can be attached to the crank arm 30.

[0072] Sprocket body 50 has a crank arm receiving opening 54 configured to receive crank arm 30, for example, in an assembled state. First sprocket mounting hole 52A, second sprocket mounting hole 52B, third sprocket mounting hole 52C, and fourth sprocket mounting hole 52D are arranged, for example, around crank arm receiving opening 54.

[0073] The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D are each configured as an individual through hole, for example. At least one of the first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D may be connected to the crank arm receiving opening 54.

[0074] The second sprocket mounting hole 52B is disposed between the first sprocket mounting hole 52A and the second sprocket mounting hole 52B in the assembly circumferential direction DCR so as to be adjacent to the first sprocket mounting hole 52A without any other sprocket mounting hole configured to receive the fastener 26 shown in Fig. 3 being interposed therebetween. The third sprocket mounting hole 52C is disposed between the second sprocket mounting hole 52B and the third sprocket mounting hole 52C in the assembly circumferential direction DCR so as to be adjacent to the second sprocket mounting hole 52B without any other sprocket mounting hole configured to receive the fastener 26 shown in Fig. 3 being interposed therebetween. The fourth sprocket mounting hole 52D is positioned adjacent to each of the first sprocket mounting hole 52A and the third sprocket mounting hole 52C in the assembly circumferential direction DCR, between the first sprocket mounting hole 52A and the fourth sprocket mounting hole 52D, and between the third sprocket mounting hole 52C and the fourth sprocket mounting hole 52D, without any other sprocket mounting holes configured to accept the fastener 26 shown in Figure 3 in between.

[0075] The positional relationship of the first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D may be described in terms of the sprocket circumferential direction DSR instead of the assembly circumferential direction DCR. The second sprocket mounting hole 52B is positioned adjacent to the first sprocket mounting hole 52A in the sprocket circumferential direction DSR without any other sprocket mounting holes between them. The third sprocket mounting hole 52C is positioned adjacent to the second sprocket mounting hole 52B in the sprocket circumferential direction DSR without any other sprocket mounting holes between them. The fourth sprocket mounting hole 52D is positioned adjacent to each of the first sprocket mounting hole 52A and the third sprocket mounting hole 52C in the sprocket circumferential direction DSR, without any other sprocket mounting holes in between.

[0076] The sprocket assembly 50 of this embodiment has only four sprocket mounting holes 52A, 52B, 52C, and 52D as sprocket mounting holes in the crank arm 30 shown in Fig. 3. The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D are, for example, arranged concentrically on the sprocket assembly 50. The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D have, for example, the same inner diameters.

[0077] The sprocket body 50 has a sprocket reference line CC corresponding to the arm reference line CX of the crank arm 30 in an assembled state. The arm reference line CX of the crank arm 30 passes through the crank bearing entry central axis 34C of the crank bearing entry opening 34 of the crank arm 30 and the pedal bearing entry central axis 36C of the pedal bearing entry opening 36 of the crank arm 30. The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D are, for example, arranged symmetrically with respect to at least one of the sprocket reference line CC and the sprocket rotation central axis 60C. The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D are, for example, arranged symmetrically with respect to the sprocket reference line CC. The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D are arranged, for example, point-symmetrically about the sprocket rotational center axis 60C. The first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D are arranged, for example, line-symmetrically about the sprocket reference line CC and point-symmetrically about the sprocket rotational center axis 60C.

[0078] As shown in FIG. 3, the sprocket body 50 has a sprocket reference line CC corresponding to the arm reference line CX of the crank arm 30 in an assembled state. The arm reference line CX of the crank arm 30 passes through the crank bearing entry central axis 34C of the crank bearing entry opening 34 of the crank arm 30 and the pedal bearing entry central axis 36C of the pedal bearing entry opening 36 of the crank arm 30. As shown in FIG. 6, the sprocket reference line CC is configured to be a boundary between the first sprocket region RC1 and the second sprocket region RC2. The first sprocket mounting hole 52A and the fourth sprocket mounting hole 52D are located in the first sprocket region RC1. The second sprocket mounting hole 52B and the third sprocket mounting hole 52C are located in the second sprocket region RC2.

[0079] The sprocket body 50 includes a plurality of sprocket spline teeth 56. The plurality of sprocket spline teeth 56 are disposed about the periphery of the crank arm receiving opening 54. The plurality of sprocket spline teeth 56 are configured to torque-transmittingly couple to the crank arm 30.

[0080] The plurality of sprocket spline teeth 56 include, for example, at least one first sprocket spline tooth 56A and at least one second sprocket spline tooth 56B. The at least one first sprocket spline tooth 56A is, for example, disposed between the first sprocket mounting hole 52A and the fourth sprocket mounting hole 52D in the assembly circumferential direction DCR. The at least one second sprocket spline tooth 56B is, for example, disposed between the second sprocket mounting hole 52B and the third sprocket mounting hole 52C in the assembly circumferential direction DCR. The plurality of sprocket spline teeth 56 include, for example, at least one first sprocket spline tooth 56A disposed between the first sprocket mounting hole 52A and the fourth sprocket mounting hole 52D in the sprocket circumferential direction DSR, and at least one second sprocket spline tooth 56B disposed between the second sprocket mounting hole 52B and the third sprocket mounting hole 52C in the sprocket circumferential direction DSR.

[0081] The at least one first sprocket spline tooth 56A includes, for example, a plurality of first sprocket spline teeth 56A. The at least one second sprocket spline tooth 56B includes, for example, a plurality of second sprocket spline teeth 56B. The number of the plurality of first sprocket spline teeth 56A is, for example, four. The number of the plurality of second sprocket spline teeth 56B is, for example, four.

[0082] One of the plurality of sprocket spline teeth 56 may be disposed, for example, at a position corresponding to the first sprocket mounting hole 52A in the sprocket circumferential direction DSR. One of the plurality of sprocket spline teeth 56 may be disposed, for example, at a position corresponding to the second sprocket mounting hole 52B in the sprocket circumferential direction DSR. One of the plurality of sprocket spline teeth 56 may be disposed, for example, at a position corresponding to the third sprocket mounting hole 52C in the sprocket circumferential direction DSR. One of the plurality of sprocket spline teeth 56 may be disposed, for example, at a position corresponding to the fourth sprocket mounting hole 52D in the sprocket circumferential direction DSR.

[0083] The plurality of sprocket spline teeth 56 may include, for example, at least one deformed tooth 56C. The deformed tooth 56C is, for example, a sprocket spline tooth 56 that is arranged at a position corresponding to each of the first sprocket mounting hole 52A, the second sprocket mounting hole 52B, the third sprocket mounting hole 52C, and the fourth sprocket mounting hole 52D in the sprocket circumferential direction DSR.

[0084] As shown in FIG. 2, for example, the third sprocket mounting hole 52C and the fourth sprocket mounting hole 52D are positioned closer to the pedal bearing receiving opening 36 than the first sprocket mounting hole 52A and the second sprocket mounting hole 52B in the assembled state.

[0085] As shown in Figure 6, the first circumferential sprocket distance LC1 is defined by the distance between the first sprocket mounting hole 52A and the second sprocket mounting hole 52B in the assembly circumferential direction DCR. The second circumferential sprocket distance LC2 is defined by the distance between the second sprocket mounting hole 52B and the third sprocket mounting hole 52C in the assembly circumferential direction DCR. The third circumferential sprocket distance LC3 is defined by the distance between the third sprocket mounting hole 52C and the fourth sprocket mounting hole 52D in the assembly circumferential direction DCR. The fourth circumferential sprocket distance LC4 is defined by the distance between the fourth sprocket mounting hole 52D and the first sprocket mounting hole 52A in the assembly circumferential direction DCR. At least one of the first circumferential sprocket distance LC1, the second circumferential sprocket distance LC2, the third circumferential sprocket distance LC3, and the fourth circumferential sprocket distance LC4 is different from at least one other of the first circumferential sprocket distance LC1, the second circumferential sprocket distance LC2, the third circumferential sprocket distance LC3, and the fourth circumferential sprocket distance LC4, for example.

[0086] The first circumferential sprocket distance LC1 may be defined by the distance between the first sprocket mounting hole 52A and the second sprocket mounting hole 52B in the sprocket circumferential direction DSR. The second circumferential sprocket distance LC2 may be defined by the distance between the second sprocket mounting hole 52B and the third sprocket mounting hole 52C in the sprocket circumferential direction DSR. The third circumferential sprocket distance LC3 may be defined by the distance between the third sprocket mounting hole 52C and the fourth sprocket mounting hole 52D in the sprocket circumferential direction DSR. The fourth circumferential sprocket distance LC4 may be defined by the distance between the fourth sprocket mounting hole 52D and the first sprocket mounting hole 52A in the sprocket circumferential direction DSR.

[0087] At least one of the second - round - direction sprocket distance LC2 and the fourth - round - direction sprocket distance LC4 is longer than at least one of, for example, the first - round - direction sprocket distance LC1 and the third - round - direction sprocket distance LC3. Each of the second - round - direction sprocket distance LC2 and the fourth - round - direction sprocket distance LC4 is longer than each of, for example, the first - round - direction sprocket distance LC1 and the third - round - direction sprocket distance LC3. Only one of the second - round - direction sprocket distance LC2 and the fourth - round - direction sprocket distance LC4 may be longer than each of the first - round - direction sprocket distance LC1 and the third - round - direction sprocket distance LC3.

[0088] The first - round - direction sprocket distance LC1 is equal to, for example, the third - round - direction sprocket distance LC3. The second - round - direction sprocket distance LC2 is equal to, for example, the fourth - round - direction sprocket distance LC4. The first - round - direction sprocket distance LC1, the second - round - direction sprocket distance LC2, the third - round - direction sprocket distance LC3, and the fourth - round - direction sprocket distance LC4 satisfy, for example, the relationship LC1 = LC3 < LC2 = LC4.

[0089] Each of the second - round - direction sprocket distance LC2 and the fourth - round - direction sprocket distance LC4 is, for example, more than twice each of the first - round - direction sprocket distance LC1 and the third - round - direction sprocket distance LC3. Each of the second - round - direction sprocket distance LC2 and the fourth - round - direction sprocket distance LC4 is, for example, more than three times each of the first - round - direction sprocket distance LC1 and the third - round - direction sprocket distance LC3. Each of the second - round - direction sprocket distance LC2 and the fourth - round - direction sprocket distance LC4 is, for example, at most eight times each of the first - round - direction sprocket distance LC1 and the third - round - direction sprocket distance LC3.

[0090] As shown in Figures 2 and 3, the crank assembly 20 further includes, for example, a fastener 26. The fastener 26 includes, for example, a first fastener 26A, a second fastener 26B, a third fastener 26C, and a fourth fastener 26D. The crank assembly 20 further includes the first fastener 26A, the second fastener 26B, the third fastener 26C, and the fourth fastener 26D. As shown in Figures 2 to 4 and 7, the first fastener 26A is configured to be received in the first sprocket mounting hole 52A and the first arm mounting hole 38A. The second fastener 26B is configured to be received in the second sprocket mounting hole 52B and the second arm mounting hole 38B. The third fastener 26C is configured to be received in the third sprocket mounting hole 52C and the third arm mounting hole 38C. The fourth fastener 26D is configured to be received in the fourth sprocket attachment hole 52D and the fourth arm attachment hole 38D. The first fastener 26A, the second fastener 26B, the third fastener 26C, and the fourth fastener 26D are configured to attach the sprocket body 50 to the crank arm 30.

[0091] 8 and 9, the crank assembly 20 may further include spacers 28 that can adjust the position of the sprocket body 50 relative to the crank arm 30. Whether or not to use the spacers 28 may be determined by an operator. The spacers 28 include, for example, a first spacer 28A, a second spacer 28B, a third spacer 28C, and a fourth spacer 28D.

[0092] The crank assembly 20 further includes, for example, a first spacer 28A, a second spacer 28B, a third spacer 28C, and a fourth spacer 28D. The first spacer 28A is disposed on the first fastener 26A so that the position of the sprocket body 50 relative to the crank arm 30 can be adjusted, for example, in the axial direction relative to the assembly rotation central axis 20C. The second spacer 28B is disposed on the second fastener 26B shown in FIG. 2 so that the position of the sprocket body 50 relative to the crank arm 30 can be adjusted, for example, in the axial direction relative to the assembly rotation central axis 20C. The third spacer 28C is disposed on the third fastener 26C so that the position of the sprocket body 50 relative to the crank arm 30 can be adjusted, for example, in the axial direction relative to the assembly rotation central axis 20C. The fourth spacer 28D is disposed on the fourth fastener 26D shown in FIG. 2 so that the position of the sprocket body 50 relative to the crank arm 30 can be adjusted, for example, in the axial direction relative to the assembly rotation central axis 20C.

[0093] The spacer 28 is disposed, for example, in the axial direction between the crank arm 30 and the sprocket body 50. The spacer 28 includes, for example, a through hole 28X in which the fastener 26 is disposed.

[0094] 9, the first spacer 28A, the second spacer 28B, the third spacer 28C, and the fourth spacer 28D may be formed as a single part. The first spacer 28A, the second spacer 28B, the third spacer 28C, and the fourth spacer 28D may be formed as separate pieces.

[0095] The operator may adjust the position of the sprocket body 50 relative to the crank arm 30 by selecting a spacer 28 of a desired thickness from a plurality of spacers 28 of different thicknesses. The operator may adjust the position of the sprocket body 50 relative to the crank arm 30 by stacking a plurality of spacers 28.

[0096] The crank arm 30 of this embodiment has four arm attachment holes 38A, 38B, 38C, and 38D. Therefore, the attachment of the sprocket body 50 to the crank arm 30 is superior compared to a crank arm having, for example, eight arm attachment holes.

[0097] In this embodiment, the third arm mounting hole 38C and the fourth arm mounting hole 38D are disposed closer to the pedal bearing receiving opening 36 than the first arm mounting hole 38A and the second arm mounting hole 38B, and the second circumferential arm distance LA2 and the fourth circumferential arm distance LA4 are each longer than the first circumferential arm distance LA1 and the third circumferential arm distance LA3, respectively. Therefore, the crank arm 30 can have a large number of arm spline teeth 40 disposed between the first arm mounting hole 38A and the fourth arm mounting hole 38D in the arm circumferential direction DAR, and a large number of arm spline teeth 40 disposed between the second arm mounting hole 38B and the third arm mounting hole 38C in the arm circumferential direction DAR. The large number of arm spline teeth 40 between the first arm mounting hole 38A and the fourth arm mounting hole 38D in the arm circumferential direction DAR, and between the second arm mounting hole 38B and the third arm mounting hole 38C in the arm circumferential direction DAR, provides excellent strength to the parts that transmit torque.

[0098] <Example of change> The description of the embodiments is an example of possible forms of a crank arm for a human-powered vehicle, a crank assembly for a human-powered vehicle, and a front sprocket for a human-powered vehicle, and is not intended to limit the forms. A crank arm for a human-powered vehicle, a crank assembly for a human-powered vehicle, and a front sprocket for a human-powered vehicle according to the present disclosure may take the form of, for example, a modified example of the embodiment shown below, or a combination of at least two modified examples that are not mutually contradictory. In the modified examples below, parts common to the embodiment are given the same reference numerals as the embodiment, and descriptions thereof are omitted.

[0099] At least one of the crank arm 30 and the sprocket body 50 may include a positioning portion that positions the rotational phase of the sprocket body 50 relative to the crank arm 30. In this modified example, the arm spline teeth 40 do not have to include the deformed tooth 40C. In this modified example, the sprocket spline teeth 56 do not have to include the deformed tooth 56C.

[0100] The fastener 26 may be a rivet instead of a bolt. When the fastener 26 includes a rivet, the arm attachment holes 38A, 38B, 38C, and 38D may be through holes. In short, as long as the fastener 26 can attach the crank arm 30 to the sprocket body 50, it can be modified as appropriate.

[0101] The term "at least one" as used herein means "one or more" of the desired options. As an example, the term "at least one" as used herein means "only one option" or "both of two options" if the number of options is two. As another example, the term "at least one" as used herein means "only one option" or "any combination of two or more options" if the number of options is three or more.

[0102] As used in this specification, ordinal numbers such as "first, second, and third" are used merely to distinguish between multiple elements having the same name and do not have any special meaning. [Explanation of symbols]

[0103] 10... human-powered vehicle, 20... crank assembly, 22... crank shaft, 24... crank arm, 26... fastener, 26A... first fastener, 26B... second fastener, 26C... third fastener, 26D... fourth fastener, 28A... first spacer, 28B... second spacer, 28C... third spacer, 28D... fourth spacer, 30... crank arm, 32... arm body, 34... crank bearing receiving opening, 36... pedal bearing receiving opening, 36C... pedal bearing receiving central axis, 38A... first arm mounting hole, 38B... second arm mounting hole, 38C... third arm Mounting hole, 38D...fourth arm mounting hole, 40...arm spline teeth, 40A...first arm spline teeth, 40B...second arm spline teeth, 50...sprocket body, 50A...sprocket teeth, 52A...first sprocket mounting hole, 52B...second sprocket mounting hole, 52C...third sprocket mounting hole, 52D...fourth sprocket mounting hole, 54...crank arm receiving opening, 56...sprocket spline teeth, 56A...first sprocket spline teeth, 56B...second sprocket spline teeth, 60...front sprocket.

Claims

1. A crank arm for a human-powered vehicle, The crank arm has an arm rotation central axis that defines an arm circumferential direction, The crank arm is a crank bearing receiving opening configured to receive a crank shaft in an assembled state of a crank assembly including the crank arm, the crank bearing receiving opening having a crank bearing receiving central axis that is coaxial with the arm rotation central axis of the crank arm; a pedal bearing receiving opening configured to receive a pedal shaft in the assembled state and having a pedal bearing receiving central axis; A first arm attachment hole; a second arm mounting hole disposed adjacent to the first arm mounting hole in the arm circumferential direction without any other arm mounting hole being interposed between the second arm mounting hole and the first arm mounting hole; a third arm mounting hole disposed adjacent to the second arm mounting hole in the arm circumferential direction with no other arm mounting hole interposed between the third arm mounting hole and the second arm mounting hole; an arm body having a fourth arm mounting hole disposed adjacent to each of the first arm mounting hole and the third arm mounting hole without any other arm mounting hole therebetween in the arm circumferential direction, a crank arm, wherein each of the first arm mounting hole, the second arm mounting hole, the third arm mounting hole, and the fourth arm mounting hole is configured to receive a fastener so that a sprocket body is attached to the crank arm.

2. the arm body has an arm reference line passing through the crank bearing-inserted central axis and the pedal bearing-inserted central axis, The arm reference line is configured to be a boundary between a first arm region and a second arm region, the first arm attachment hole and the fourth arm attachment hole are disposed in the first arm region, the second arm attachment hole and the third arm attachment hole are disposed in the second arm region, the first arm mounting hole, the second arm mounting hole, the third arm mounting hole, and the fourth arm mounting hole are arranged in the arm circumferential direction so as to surround the crank bearing receiving opening, the third arm attachment hole and the fourth arm attachment hole are disposed closer to the pedal bearing receiving opening than the first arm attachment hole and the second arm attachment hole, a first circumferential arm distance is defined by a distance between the first arm attachment hole and the second arm attachment hole in the arm circumferential direction; a second circumferential arm distance is defined by a distance between the second arm attachment hole and the third arm attachment hole in the arm circumferential direction; a third circumferential arm distance is defined by a distance between the third arm attachment hole and the fourth arm attachment hole in the arm circumferential direction; a fourth circumferential arm distance is defined by a distance between the fourth arm attachment hole and the first arm attachment hole in the arm circumferential direction; 2. The crank arm of claim 1, wherein at least one of the first circumferential arm distance, the second circumferential arm distance, the third circumferential arm distance and the fourth circumferential arm distance is different from at least one other of the first circumferential arm distance, the second circumferential arm distance, the third circumferential arm distance and the fourth circumferential arm distance.

3. 3. A crank arm according to claim 2, wherein at least one of the second circumferential arm distance and the fourth circumferential arm distance is greater than at least one of the first circumferential arm distance and the third circumferential arm distance.

4. 4. A crank arm according to claim 3, wherein each of the second and fourth circumferential arm distances is greater than each of the first and third circumferential arm distances.

5. A crank arm according to claim 4, wherein said first circumferential arm distance is equal to said third circumferential arm distance.

6. A crank arm according to claim 4, wherein said second circumferential arm distance is equal to said fourth circumferential arm distance.

7. 5. A crank arm according to claim 4, wherein each of the second circumferential arm distance and the fourth circumferential arm distance is greater than or equal to twice each of the first circumferential arm distance and the third circumferential arm distance.

8. 8. A crank arm according to claim 7, wherein each of the second and fourth circumferential arm distances is greater than or equal to three times each of the first and third circumferential arm distances.

9. 5. A crank arm according to claim 4, wherein each of the second and fourth circumferential arm distances is less than or equal to eight times each of the first and third circumferential arm distances.

10. 2. The crank arm of claim 1, wherein each of the first arm attachment hole, the second arm attachment hole, the third arm attachment hole and the fourth arm attachment hole is configured for threaded engagement with the fastener.

11. 2. The crank arm according to claim 1, wherein the arm body includes a plurality of arm spline teeth arranged around the crank bearing receiving opening in the arm circumferential direction and configured to couple with the sprocket body in a torque transmitting manner.

12. The plurality of arm spline teeth include at least one first arm spline tooth disposed between the first arm attachment hole and the fourth arm attachment hole in the arm circumferential direction; The crank arm according to claim 11, further comprising: at least one second arm spline tooth arranged between the second arm attachment hole and the third arm attachment hole in the arm circumferential direction.

13. the at least one first arm spline tooth includes a plurality of first arm spline teeth, A crank arm according to claim 12, wherein said at least one second arm spline tooth comprises a plurality of second arm spline teeth.

14. the arm body has an arm reference line passing through the crank bearing-inserted central axis and the pedal bearing-inserted central axis, 2. The crank arm according to claim 1, wherein the first arm attachment hole, the second arm attachment hole, the third arm attachment hole, and the fourth arm attachment hole are arranged symmetrically with respect to at least one of the arm reference line and the arm rotation central axis.

15. A crank assembly for a human-powered vehicle, the crank assembly having an assembly rotation central axis that coincides with the arm rotation central axis of the crank arm in the assembled state, the assembly rotation center axis defines an assembly circumferential direction; The crank assembly includes: The crank arm according to claim 1 ; The sprocket body, The sprocket body is a first sprocket mounting hole aligned with the first arm mounting hole of the crank arm in the assembled state; a second sprocket mounting hole aligned with the second arm mounting hole of the crank arm in the assembled state; a third sprocket mounting hole aligned with the third arm mounting hole of the crank arm in the assembled state; a fourth sprocket mounting hole aligned with the fourth arm mounting hole of the crank arm in the assembled state, a crank assembly, wherein each of the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole, and the fourth sprocket mounting hole is configured to receive a fastener such that the sprocket body is attached to the crank arm.

16. the second sprocket mounting hole is disposed adjacent to the first sprocket mounting hole in the assembly circumferential direction with no other sprocket mounting hole configured to receive a fastener between the first sprocket mounting hole and the second sprocket mounting hole, the third sprocket mounting hole is disposed adjacent to the second sprocket mounting hole in the assembly circumferential direction with no other sprocket mounting hole configured to receive a fastener between the second sprocket mounting hole and the third sprocket mounting hole, 16. The crank assembly according to claim 15, wherein the fourth sprocket mounting hole is positioned adjacent to each of the first sprocket mounting hole and the third sprocket mounting hole in the assembly circumferential direction, without any other sprocket mounting hole configured to receive a fastener, between the first sprocket mounting hole and the fourth sprocket mounting hole and between the third sprocket mounting hole and the fourth sprocket mounting hole.

17. the arm body has an arm reference line passing through the crank bearing-inserted central axis and the pedal bearing-inserted central axis, the sprocket body has a sprocket reference line which corresponds to the arm reference line of the crank arm in the assembled state, The sprocket reference line is configured to be a boundary between a first sprocket region and a second sprocket region; the first sprocket mounting hole and the fourth sprocket mounting hole are disposed in the first sprocket region; 16. The crank assembly of claim 15, wherein the second sprocket mounting hole and the third sprocket mounting hole are located in the second sprocket region.

18. the sprocket body has a crank arm receiving opening configured to receive the crank arm in the assembled state; 16. The crank assembly of claim 15, wherein the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole, and the fourth sprocket mounting hole are disposed around the crank arm receiving opening.

19. 19. The crank assembly of claim 18, wherein the sprocket body includes a plurality of sprocket spline teeth disposed about the crank arm receiving opening and configured to torque-transmittingly couple to the crank arm.

20. The plurality of sprocket spline teeth include at least one first sprocket spline tooth disposed between the first sprocket mounting hole and the fourth sprocket mounting hole in the assembly circumferential direction; 20. The crank assembly of claim 19, further comprising: at least one second sprocket spline tooth disposed between the second sprocket mounting hole and the third sprocket mounting hole in the assembly circumferential direction.

21. the at least one first sprocket spline tooth includes a plurality of first sprocket spline teeth, The crank assembly of claim 20 , wherein the at least one second sprocket spline tooth comprises a plurality of second sprocket spline teeth.

22. 16. The crank assembly of claim 15, wherein the third sprocket mounting hole and the fourth sprocket mounting hole are positioned closer to the pedal bearing receiving opening than the first sprocket mounting hole and the second sprocket mounting hole in the assembled state.

23. a first circumferential sprocket distance is defined by a distance between the first sprocket mounting hole and the second sprocket mounting hole in the assembly circumferential direction; a second circumferential sprocket distance is defined by a distance between the second sprocket mounting hole and the third sprocket mounting hole in the assembly circumferential direction; a third circumferential sprocket distance is defined by a distance between the third sprocket mounting hole and the fourth sprocket mounting hole in the assembly circumferential direction; a fourth circumferential sprocket distance is defined by a distance between the fourth sprocket mounting hole and the first sprocket mounting hole in the assembly circumferential direction; 16. The crank assembly of claim 15, wherein at least one of the first circumferential sprocket distance, the second circumferential sprocket distance, the third circumferential sprocket distance, and the fourth circumferential sprocket distance is different from at least one other of the first circumferential sprocket distance, the second circumferential sprocket distance, the third circumferential sprocket distance, and the fourth circumferential sprocket distance.

24. 24. The crank assembly of claim 23, wherein at least one of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than at least one of the first circumferential sprocket distance and the third circumferential sprocket distance.

25. 25. The crank assembly of claim 24, wherein each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than each of the first circumferential sprocket distance and the third circumferential sprocket distance.

26. The sprocket body is a plurality of sprocket teeth formed integrally with the sprocket body; 16. The crank assembly of claim 15, including a plurality of sprocket teeth and including one of the sprocket body and a separate sprocket teeth ring.

27. a first fastener configured to be received in the first sprocket attachment hole and the first arm attachment hole; a second fastener configured to be received in the second sprocket attachment hole and the second arm attachment hole; a third fastener configured to be received in the third sprocket attachment hole and the third arm attachment hole; a fourth fastener configured to be received in the fourth sprocket attachment hole and the fourth arm attachment hole; 16. The crank assembly of claim 15, wherein the first fastener, the second fastener, the third fastener, and the fourth fastener are configured to attach the sprocket body to the crank arm.

28. a first spacer disposed on the first fastener to adjust a position of the sprocket body relative to the crank arm in an axial direction relative to the assembly rotation axis; a second spacer disposed on the second fastener to adjust a position of the sprocket body relative to the crank arm in an axial direction relative to the assembly rotation center axis; a third spacer disposed on the third fastener to adjust a position of the sprocket body relative to the crank arm in an axial direction relative to the assembly rotation center axis; 28. The crank assembly of claim 27, further comprising: a fourth spacer disposed on the fourth fastener to allow adjustment of a position of the sprocket body relative to the crank arm in an axial direction relative to the assembly central axis of rotation.

29. A front sprocket for a human-powered vehicle, the front sprocket having a sprocket central axis of rotation that defines a circumferential direction of the sprocket; The front sprocket includes a sprocket body. The sprocket body is a crank arm receiving opening configured to receive the crank arm in an assembled state of a crank assembly including the front sprocket and the crank arm; A first sprocket mounting hole; a second sprocket mounting hole disposed adjacent to the first sprocket mounting hole in the circumferential direction of the sprocket with no other sprocket mounting hole interposed between the second sprocket mounting hole and the first sprocket mounting hole; a third sprocket mounting hole disposed adjacent to the second sprocket mounting hole in the circumferential direction of the sprocket with no other sprocket mounting hole interposed between the third sprocket mounting hole and the second sprocket mounting hole; a fourth sprocket mounting hole disposed adjacent to each of the first sprocket mounting hole and the third sprocket mounting hole in a circumferential direction of the sprocket, without any other sprocket mounting hole therebetween, a front sprocket, wherein each of the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole, and the fourth sprocket mounting hole are configured to receive a fastener so that the sprocket body is attached to the crank arm.

30. the sprocket body has a sprocket reference line which corresponds to an arm reference line of the crank arm in the assembled state, the arm reference line of the crank arm passes through a crank bearing-insertion central axis of a crank bearing-insertion opening of the crank arm and a pedal bearing-insertion central axis of a pedal bearing-insertion opening of the crank arm, The sprocket reference line is configured to be a boundary between a first sprocket region and a second sprocket region; the first sprocket mounting hole and the fourth sprocket mounting hole are disposed in the first sprocket region; the second sprocket mounting hole and the third sprocket mounting hole are disposed in the second sprocket region; the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole, and the fourth sprocket mounting hole are disposed around the crank arm receiving opening; the third sprocket mounting hole and the fourth sprocket mounting hole are disposed in a position closer to the pedal bearing receiving opening than the first sprocket mounting hole and the second sprocket mounting hole in the assembled state, a first circumferential sprocket distance is defined as a distance between the first sprocket mounting hole and the second sprocket mounting hole in a circumferential direction of the sprocket; a second circumferential sprocket distance is defined as a distance between the second sprocket mounting hole and the third sprocket mounting hole in a circumferential direction of the sprocket; a third circumferential sprocket distance is defined as a distance between the third sprocket mounting hole and the fourth sprocket mounting hole in a circumferential direction of the sprocket; a fourth circumferential sprocket distance is defined as a distance between the fourth sprocket mounting hole and the first sprocket mounting hole in a circumferential direction of the sprocket; 30. The front sprocket of claim 29, wherein at least one of the first circumferential sprocket distance, the second circumferential sprocket distance, the third circumferential sprocket distance, and the fourth circumferential sprocket distance is different from at least one other of the first circumferential sprocket distance, the second circumferential sprocket distance, the third circumferential sprocket distance, and the fourth circumferential sprocket distance.

31. At least one of the second circumferential sprocket distance and the fourth circumferential sprocket distance is at least one of the first circumferential sprocket distance and the third circumferential sprocket distance 31. A front sprocket according to claim 30, which is long.

32. 32. The front sprocket of claim 31, wherein each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than each of the first circumferential sprocket distance and the third circumferential sprocket distance.

33. 33. The front sprocket of claim 32, wherein said first circumferential sprocket distance is equal to said third circumferential sprocket distance.

34. 33. The front sprocket of claim 32, wherein said second circumferential sprocket distance is equal to said fourth circumferential sprocket distance.

35. 33. The front sprocket of claim 32, wherein each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than or equal to twice each of the first circumferential sprocket distance and the third circumferential sprocket distance.

36. 33. The front sprocket of claim 32, wherein each of the second circumferential sprocket distance and the fourth circumferential sprocket distance is greater than or equal to three times each of the first circumferential sprocket distance and the third circumferential sprocket distance.

37. 30. The front sprocket of claim 29, wherein the sprocket body includes a plurality of sprocket spline teeth disposed about the crank arm receiving opening and configured to torque-transmittingly couple to the crank arm.

38. The plurality of sprocket spline teeth include at least one first sprocket spline tooth disposed between the first sprocket mounting hole and the fourth sprocket mounting hole in a circumferential direction of the sprocket; 38. The front sprocket of claim 37, further comprising: at least one second sprocket spline tooth circumferentially disposed between said second sprocket mounting hole and said third sprocket mounting hole.

39. the at least one first sprocket spline tooth includes a plurality of first sprocket spline teeth, 39. The front sprocket of claim 38, wherein said at least one second sprocket spline tooth comprises a plurality of second sprocket spline teeth.

40. the sprocket body has a sprocket reference line which corresponds to an arm reference line of the crank arm in the assembled state, the arm reference line of the crank arm passes through a crank bearing-insertion central axis of a crank bearing-insertion opening of the crank arm and a pedal bearing-insertion central axis of a pedal bearing-insertion opening of the crank arm, 30. The front sprocket of claim 29, wherein the first sprocket mounting hole, the second sprocket mounting hole, the third sprocket mounting hole, and the fourth sprocket mounting hole are symmetrically positioned about at least one of the sprocket reference line and the sprocket central rotational axis.

41. The sprocket body is a plurality of sprocket teeth formed integrally with the sprocket body; 30. A front sprocket according to claim 29, including a plurality of sprocket teeth and including one of the sprocket body and a separate sprocket tooth ring.

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