Bicycle Chain

Abstract

To provide a bicycle chain excellent in abrasion resistance.SOLUTION: A bicycle chain includes a first slide surface having first hardness of 1000 HV or more, and a second slide surface constituted to come into contact with the first slide surface in usage of the bicycle chain. The second slide surface has second hardness of 1000 HV or more. A ratio of the first hardness to the second hardness is 1.2 or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to bicycle chains. [Background technology]

[0002] Patent Document 1 discloses a technique related to a bicycle chain. The chain in Patent Document 1 has alternating, continuous outer links and inner links, which are connected to each other at their respective connection ends by rivets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-105438 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to prevent a decrease in the efficiency of driving the front and rear sprockets of a bicycle, or to prevent slack in the bicycle chain, it is preferable that at least one of the parts that slide against each other when the bicycle chain is in use has high wear resistance.

[0005] An object of the present disclosure is to provide a bicycle chain that is highly resistant to wear. [Means for solving the problem]

[0006] A bicycle chain in accordance with a first aspect of the present disclosure includes a first sliding surface having a first hardness of 1000 HV or greater, and a second sliding surface configured to contact the first sliding surface during use of the bicycle chain, the second sliding surface having a second hardness of 1000 HV or greater, wherein a ratio of the first hardness to the second hardness is 1.2 or greater. According to the bicycle chain of the first aspect described above, by making the first hardness of the first sliding surface and the second hardness of the second sliding surface different, the wear resistance of the first sliding surface and the second sliding surface is improved compared to when the first hardness of the first sliding surface is equal to the second hardness of the second sliding surface.

[0007] In a bicycle chain according to a second aspect of the present invention, the ratio of the first hardness to the second hardness is 5 or less. According to the bicycle chain of the second aspect described above, the first hardness of the first sliding surface is not excessively greater than the second hardness of the second sliding surface, thereby improving the wear resistance of the first sliding surface and the second sliding surface.

[0008] A bicycle chain of a third aspect according to the first or second aspects, wherein a first surface treatment is applied to the first sliding surface and a second surface treatment is applied to the second sliding surface, and the first surface treatment is different from the second surface treatment. According to the bicycle chain of the third aspect, the first hardness of the first sliding surface and the second hardness of the second sliding surface can be set to 1000 HV or more by the first surface treatment and the second surface treatment. By making the first surface treatment different from the second surface treatment, the first sliding surface and the second sliding surface can be configured so that the first hardness is different from the second hardness, improving the wear resistance of the first sliding surface and the second sliding surface.

[0009] In a fourth aspect of the bicycle chain according to any one of the first to third aspects, the bicycle chain further comprises a first inner link plate, a second inner link plate, a first outer link plate, a second outer link plate, a pin, and a roller, wherein the first inner link plate includes a first inner link end portion including a first inner link hole having a first inner link central axis, a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis, a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion, a first inner link face, and a second inner link face disposed on the opposite side of the first inner link face in the first inner link axial direction relative to the first inner link central axis, and the second inner link plate includes a third inner link end portion including a third inner link hole having a third inner link central axis, and a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the third inner link central axis. a link end portion, a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion, a third inner link face configured to face the first inner link face of the first inner link plate in the first inner link axial direction in an assembled state of the bicycle chain, and a fourth inner link face arranged on the opposite side of the third inner link face in the second inner link axial direction relative to the third inner link central axis, the first outer link plate being configured to be adjacent to the first inner link plate in an assembled state of the bicycle chain so as not to sandwich another inner link plate or another outer link plate therebetween, a first outer link end portion including a first outer link hole having a first outer link central axis, a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis, a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion, and a first outer link surface,a second outer link surface disposed on the opposite side of the first outer link surface in a first outer link axial direction relative to the first outer link central axis, the second outer link plate being configured to be adjacent to the second inner link plate in an assembled state of the bicycle chain without sandwiching another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; and a fourth outer link surface arranged on the opposite side of the third outer link surface in the second outer link axial direction relative to the third outer link central axis in an assembled state of the bicycle chain, the pin is configured to be inserted through the first outer link hole and the third outer link hole and pass through the first inner link hole and the third inner link hole in an assembled state of the bicycle chain, and the roller is configured to be located between the first inner link surface of the first inner link plate and the third inner link surface of the second inner link plate in an assembled state of the bicycle chain. According to the bicycle chain of the fourth aspect described above, the wear resistance of the bicycle chain, which includes a first inner link plate, a second inner link plate, a first outer link plate, a second outer link plate, a pin, and a roller, is improved.

[0010] In a bicycle chain of a fifth side following the fourth side, one of the first sliding surface and the second sliding surface is formed on the first inner link plate, and the other of the first sliding surface and the second sliding surface is formed on at least one of the first outer link plate, the pin, and the roller. According to the bicycle chain of the fifth aspect described above, the wear resistance of the first inner link plate and the parts of the bicycle chain that slide against the first inner link plate is improved, thereby preventing the bicycle chain from becoming loose or reducing drive efficiency due to wear of the bicycle chain.

[0011] A bicycle chain of a sixth aspect according to the fourth aspect further includes a bush having a bush hole, the bush being configured to be inserted into the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state, and the pin being configured to pass through the bush hole when the bicycle chain is in an assembled state. According to the bicycle chain of the sixth aspect, the wear resistance of the bushings and pins is improved, so that slack in the bicycle chain can be reduced.

[0012] In a bicycle chain of a seventh side following the sixth side, one of the first sliding surface and the second sliding surface is formed on the first inner link plate, and the other of the first sliding surface and the second sliding surface is formed on the first outer link plate and at least one of the rollers. According to the bicycle chain of the seventh aspect, it is possible to prevent a decrease in drive efficiency caused by wear of the bicycle chain.

[0013] In a bicycle chain having an eighth side following the sixth side, one of the first sliding surface and the second sliding surface is formed on the first outer link plate, and the other of the first sliding surface and the second sliding surface is formed on the bush. According to the bicycle chain of the eighth aspect, the wear resistance between the first outer link plate and the bushing is improved.

[0014] In a bicycle chain of a ninth aspect according to the sixth aspect, one of the first sliding surface and the second sliding surface is formed on the bush, and the other of the first sliding surface and the second sliding surface is formed on at least one of the pin and the roller. According to the bicycle chain of the ninth aspect, the wear resistance of the bushings and at least one of the pins and rollers is improved, thereby preventing the bicycle chain from becoming loose or reducing driving efficiency due to wear of the bicycle chain.

[0015] A bicycle chain according to a tenth aspect of the present disclosure, comprising: a first inner link plate, a second inner link plate, a first outer link plate, a second outer link plate, a first pin, a second pin, a first surface treatment, and a second surface treatment, wherein the first inner link plate includes a first inner link end portion including a first inner link hole having a first inner link central axis, a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis, a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion, a first inner link face, and a second inner link face disposed on the opposite side of the first inner link face in a first inner link axial direction relative to the first inner link central axis, and the second inner link plate includes a third inner link end portion including a third inner link hole having a third inner link central axis, and a second inner link end portion including a third inner link hole having a third inner link central axis extending parallel to the third inner link central axis. a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the first inner link central axis; a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion; a third inner link face configured to face the first inner link face of the first inner link plate in the first inner link axial direction in an assembled state of the bicycle chain; and a fourth inner link face disposed on the opposite side of the third inner link face in the second inner link axial direction relative to the third inner link central axis, wherein the first outer link plate is configured to be adjacent to the first inner link plate in an assembled state of the bicycle chain so as not to sandwich another inner link plate or another outer link plate therebetween; a first outer link end portion including a first outer link hole having a first outer link central axis; and a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis.a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion, a first outer link surface, and a second outer link surface arranged on the opposite side of the first outer link surface in a first outer link axial direction relative to the first outer link central axis, wherein the second outer link plate is configured to be adjacent to the second inner link plate in an assembled state of the bicycle chain so as not to sandwich another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; and a third outer link surface configured to face the first outer link surface of the first outer link plate in the first outer link axial direction in an assembled state of the bicycle chain. and a fourth outer link surface disposed on the opposite side of the third outer link surface in a second outer link axial direction relative to the third outer link central axis, wherein the first pin is configured to be inserted through the first outer link hole and the third outer link hole and pass through the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state, and the second pin is configured to be inserted through the second outer link hole and the fourth outer link hole and pass through the second inner link hole and the fourth inner link hole when the bicycle chain is in an assembled state, and the first surface treatment is applied to at least one of the first pin, the first inner link hole and the third inner link hole, or the first surface treatment is applied to at least one of the first inner link hole and the second inner link hole, and when the first surface treatment is applied to at least one of the first pin, the first inner link hole and the third inner link hole, the second surface treatment is applied to the second pin, the second inner link hole and theor when the first surface treatment is applied to at least one of the first and second inner link holes, the second surface treatment is applied to at least one of the third and fourth inner link holes, and the first surface treatment is different from the second surface treatment; According to the bicycle chain of the tenth aspect, by making the first surface treatment different from the second surface treatment, it is possible to apply a surface treatment with excellent abrasion resistance to areas where excellent abrasion resistance is required, and to apply a low-cost surface treatment to areas where excellent abrasion resistance is not required, thereby achieving an excellent balance between the abrasion resistance and cost of the bicycle chain. Effect of the Invention

[0016] The bicycle chain of the present disclosure has excellent wear resistance. [Brief description of the drawings]

[0017] [Figure 1] A schematic diagram of a bicycle, seen from above. [Diagram 2] 1 is a perspective view of a bicycle chain according to a first embodiment; [Diagram 3] 3 is a cross-sectional view of the bicycle chain of the first embodiment taken along line III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view of the bicycle chain of the first embodiment taken along line IV-IV in FIG. 3. [Diagram 5] 4 is a cross-sectional view of the bicycle chain of the first embodiment taken along line VV in FIG. 3. [Figure 6] 4 is a table showing an example of the relationship between the first sliding surface, the second sliding surface, and the components of a bicycle chain. [Figure 7] FIG. 5 is a cross-sectional view of a bicycle chain according to a second embodiment. [Figure 8] 4 is a table showing an example of the relationship between the first sliding surface, the second sliding surface, and the components of a bicycle chain. [Figure 9] FIG. 11 is a cross-sectional view of a bicycle chain according to a third embodiment. [Figure 10]FIG. 10 is a cross-sectional view of a bicycle chain according to a fourth embodiment. [Figure 11] 13 is a cross-sectional view of a modified bicycle chain. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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.

[0019] First Embodiment A bicycle to which a bicycle chain is applied will be described with reference to FIG. FIG. 1 shows a top view of bicycle A. Bicycle A includes a drivetrain B. Drivetrain B is a chain drive type. Drivetrain B includes a bicycle crank assembly C, a bicycle sprocket (hereinafter referred to as "sprocket D"), and a bicycle chain 10. Sprocket D has sprocket teeth with which bicycle chain 10 engages. Sprocket D includes a front sprocket E and a rear sprocket F. Bicycle crank assembly C includes a crankshaft Ca that is rotatably supported on the frame of bicycle A, and a pair of crank arms Cb provided at each end of the crankshaft Ca. A pedal is rotatably attached to the tip of each crank arm Cb.

[0020] The front sprocket E is attached to the crankshaft Ca so as to rotate integrally with the crankshaft Ca. The rear sprocket F is attached to the hub of the rear wheel. The bicycle chain 10 is wound around the front sprocket E and the rear sprocket F. Driving force applied to the pedals by a user riding bicycle A is transmitted to the rear wheel via the front sprocket E, the bicycle chain 10, and the rear sprocket F.

[0021] The detailed configuration of the bicycle chain 10 will be described with reference to FIGS. As shown in Figure 2, the bicycle chain 10 further includes a first inner link plate 12, a second inner link plate 14, a first outer link plate 16, a second outer link plate 18, a pin 20, and a roller 22. Preferably, the bicycle chain 10 further includes a bushing 24 having a bushing hole 24A. More preferably, the bicycle chain 10 further includes an additional pin 26, an additional roller 28, and an additional bushing 30. In one example, the first inner link plate 12, the second inner link plate 14, the first outer link plate 16, the second outer link plate 18, the pin 20, the roller 22, the bushing 24, the additional pin 26, the additional roller 28, and the additional bushing 30 are made of the same material. In this embodiment, the first inner link plate 12, the second inner link plate 14, the first outer link plate 16, the second outer link plate 18, the pin 20, the roller 22, the bushing 24, the additional pin 26, the additional roller 28, and the additional bushing 30 are made of low carbon steel.

[0022] 3, the first inner link plate 12 includes a first inner link end portion 32 including a first inner link hole 32A having a first inner link central axis AX1, a second inner link end portion 34 including a second inner link hole 34A having a second inner link central axis AX2 extending parallel to the first inner link central axis AX1, and a first inner link middle portion 36 connecting the first inner link end portion 32 and the second inner link end portion 34. The first inner link plate 12 includes a first inner link surface 12A and a second inner link surface 12B disposed on the opposite side of the first inner link surface 12A in the first inner link axial direction DA relative to the first inner link central axis AX1.

[0023] The first inner link end portion 32 is divided into a first peripheral portion 32B around the first inner link hole 32A and a first outer peripheral portion 32C around the first peripheral portion 32B. In this embodiment, the second inner link surface 12B in the first outer peripheral portion 32C is at least partially offset in the first inner link axial direction DA relative to the second inner link surface 12B in the first inner link intermediate portion 36 toward the axial center plane 10A of the bicycle chain 10. However, the second inner link surface 12B in the first outer peripheral portion 32C may be configured to be flush with the second inner link surface 12B in the first inner link intermediate portion 36. Furthermore, in this embodiment, the second inner link surface 12B in the first peripheral portion 32B is offset in the first inner link axial direction DA relative to the second inner link surface 12B in the first outer peripheral portion 32C toward the axial center plane 10A of the bicycle chain 10. However, the second inner link surface 12B at the first peripheral portion 32B may be configured to be flush with the second inner link surface 12B at the first outer circumferential portion 32C.

[0024] The second inner link end portion 34 is divided into a second peripheral portion 34B around the second inner link hole 34A and a second outer peripheral portion 34C around the second peripheral portion 34B. In this embodiment, the second inner link surface 12B in the second outer peripheral portion 34C is at least partially offset toward the axial center plane 10A of the bicycle chain 10 relative to the second inner link surface 12B in the first inner link intermediate portion 36 in the third inner link axial direction DC relative to the second inner link central axis AX2. However, the second inner link surface 12B in the second outer peripheral portion 34C may be configured to be flush with the second inner link surface 12B in the first inner link intermediate portion 36. Furthermore, in this embodiment, the second inner link surface 12B in the second peripheral portion 34B is offset toward the axial center plane 10A of the bicycle chain 10 relative to the second inner link surface 12B in the second outer peripheral portion 34C in the third inner link axial direction DC. However, the second inner link surface 12B at the second peripheral portion 34B may be configured to be flush with the second inner link surface 12B at the second outer periphery portion 34C.

[0025] The first inner link surface 12A of the first inner link end portion 32, the second inner link end portion 34, and the first inner link intermediate portion 36 of the first inner link plate 12 are each provided with one or more chamfered portions 38. As shown in FIG. 4, in this embodiment, the first inner link end portion 32, the second inner link end portion 34, and the first inner link intermediate portion 36 are each provided with two chamfered portions 38. The two chamfered portions 38 of the first inner link end portion 32 are provided on the outer periphery of the first inner link end portion 32. The two chamfered portions 38 of the second inner link end portion 34 are provided on the outer periphery of the second inner link end portion 34. The two chamfered portions 38 of the first inner link intermediate portion 36 are provided at a distance from each other in the orthogonal direction SB that is perpendicular to both the running direction SA of the bicycle chain 10 and the width direction of the bicycle A when the bicycle A is in use.

[0026] 3, the second inner link plate 14 includes a third inner link end portion 40 including a third inner link hole 40A having a third inner link central axis AX3, a fourth inner link end portion 42 including a fourth inner link hole 42A having a fourth inner link central axis AX4 extending parallel to the third inner link central axis AX3, and a second inner link intermediate portion 44 connecting the third inner link end portion 40 and the fourth inner link end portion 42. The second inner link plate 14 includes a third inner link surface 14A configured to face the first inner link surface 12A of the first inner link plate 12 in the first inner link axial direction DA in the assembled state of the bicycle chain 10, and a fourth inner link surface 14B disposed on the opposite side of the third inner link surface 14A in the second inner link axial direction DB with respect to the third inner link central axis AX3.

[0027] The third inner link end portion 40 is divided into a third peripheral portion 40B around the third inner link hole 40A and a third outer peripheral portion 40C around the third peripheral portion 40B. In this embodiment, the fourth inner link surface 14B in the third outer peripheral portion 40C is at least partially offset toward the axial center plane 10A of the bicycle chain 10 relative to the fourth inner link surface 14B in the second inner link intermediate portion 44 in the second inner link axial direction DB. However, the fourth inner link surface 14B in the third outer peripheral portion 40C may be configured to be flush with the fourth inner link surface 14B in the second inner link intermediate portion 44. Furthermore, in this embodiment, the fourth inner link surface 14B in the third peripheral portion 40B is offset toward the axial center plane 10A of the bicycle chain 10 relative to the fourth inner link surface 14B in the third outer peripheral portion 40C in the second inner link axial direction DB. However, the fourth inner link surface 14B at the third peripheral portion 40B may be configured to be flush with the fourth inner link surface 14B at the third outer circumferential portion 40C.

[0028] The fourth inner link end portion 42 is divided into a fourth peripheral portion 42B around the fourth inner link hole 42A and a fourth outer peripheral portion 42C around the fourth peripheral portion 42B. In this embodiment, the fourth inner link surface 14B in the fourth outer peripheral portion 42C is at least partially offset toward the axial center plane 10A of the bicycle chain 10 relative to the fourth inner link surface 14B in the second inner link intermediate portion 44 in the fourth inner link axial direction DD relative to the fourth inner link central axis AX4. However, the fourth inner link surface 14B in the fourth outer peripheral portion 42C may be configured to be flush with the fourth inner link surface 14B in the second inner link intermediate portion 44. Furthermore, in this embodiment, the fourth inner link surface 14B in the fourth peripheral portion 42B is offset toward the axial center plane 10A of the bicycle chain 10 relative to the fourth inner link surface 14B in the fourth outer peripheral portion 42C in the fourth inner link axial direction DD. However, the fourth inner link surface 14B at the fourth peripheral portion 42B may be configured to be flush with the fourth inner link surface 14B at the fourth outer circumferential portion 42C.

[0029] The third inner link end portion 40, the fourth inner link end portion 42, and the third inner link surface 14A of the second inner link plate 14 at the second inner link intermediate portion 44 are each provided with one or more chamfered portions 46. As shown in FIG. 5, in this embodiment, the third inner link end portion 40, the fourth inner link end portion 42, and the second inner link intermediate portion 44 are each provided with two chamfered portions 46. The two chamfered portions 46 of the third inner link end portion 40 are provided on the outer periphery of the third inner link end portion 40. The two chamfered portions 46 of the fourth inner link end portion 42 are provided on the outer periphery of the fourth inner link end portion 42. The two chamfered portions 46 of the second inner link intermediate portion 44 are provided spaced apart in the orthogonal direction SB.

[0030] 3, the first outer link plate 16 is configured to be adjacent to the first inner link plate 12 without sandwiching another inner link plate or another outer link plate therebetween when the bicycle chain 10 is assembled. The first outer link plate 16 includes a first outer link end portion 48 including a first outer link hole 48A having a first outer link central axis BX1, a second outer link end portion 50 including a second outer link hole 50A having a second outer link central axis BX2 extending parallel to the first outer link central axis BX1, and a first outer link intermediate portion 52 connecting the first outer link end portion 48 and the second outer link end portion 50. The first outer link plate 16 includes a first outer link surface 16A and a second outer link surface 16B disposed on the opposite side of the first outer link surface 16A in the first outer link axial direction DE relative to the first outer link central axis BX1.

[0031] The second outer link plate 18 is configured to be adjacent to the second inner link plate 14 without sandwiching another inner link plate or another outer link plate therebetween when the bicycle chain 10 is in an assembled state. The second outer link plate 18 includes a third outer link end portion 54 including a third outer link hole 54A having a third outer link central axis BX3, a fourth outer link end portion 56 including a fourth outer link hole 56A having a fourth outer link central axis BX4 extending parallel to the third outer link central axis BX3, and a second outer link intermediate portion 58 connecting the third outer link end portion 54 and the fourth outer link end portion 56. The second outer link plate 18 includes a third outer link surface 18A that is configured to face the first outer link surface 16A of the first outer link plate 16 in the first outer link axial direction DE when the bicycle chain 10 is in an assembled state, and a fourth outer link surface 18B that is positioned on the opposite side of the third outer link surface 18A in the second outer link axial direction DF relative to the third outer link central axis BX3.

[0032] The pin 20 is configured to be inserted through the first outer link hole 48A and the third outer link hole 54A and pass through the first inner link hole 32A and the third inner link hole 40A when the bicycle chain 10 is assembled. Preferably, the pin 20 is press-fitted into the first outer link hole 48A and the third outer link hole 54A when the bicycle chain 10 is assembled. The additional pin 26 is configured to be inserted through the second outer link hole 50A and the fourth outer link hole 56A and pass through the second inner link hole 34A and the fourth inner link hole 42A when the bicycle chain 10 is assembled. Preferably, the additional pin 26 is press-fitted into the second outer link hole 50A and the fourth outer link hole 56A when the bicycle chain 10 is assembled. The pin 20 and the additional pin 26 are cylindrical in shape.

[0033] The first outer link plate 16 and the second outer link plate 18 are connected by a pin 20 and an additional pin 26. The first inner link plate 12 and the second inner link plate 14 are connected by a pin 20 and an additional pin 26. The combined body of the first inner link plate 12 and the second inner link plate 14 is rotatably connected to the combined body of the first outer link plate 16 and the second outer link plate 18 about the central axis of the pin 20 and the central axis of the additional pin 26. The combined body of the first inner link plate 12 and the second inner link plate 14 and the combined body of the first outer link plate 16 and the second outer link plate 18 are arranged alternately and connected in a loop shape.

[0034] The roller 22 is configured to be located between the first inner link surface 12A of the first inner link plate 12 and the third inner link surface 14A of the second inner link plate 14 in the assembled state of the bicycle chain 10. The roller 22 is disposed between the first inner link end portion 32 of the first inner link plate 12 and the third inner link end portion 40 of the second inner link plate 14. The roller 22 has a roller hole 22A through which the bush 24 is inserted. The roller 22 is rotatable relative to the bush 24. The additional roller 28 is configured to be located between the first inner link surface 12A of the first inner link plate 12 and the third inner link surface 14A of the second inner link plate 14 in the assembled state of the bicycle chain 10. The additional roller 28 is disposed between the second inner link end portion 34 of the first inner link plate 12 and the fourth inner link end portion 42 of the second inner link plate 14. The additional roller 28 has a roller hole 28A through which the additional bush 30 is inserted. The additional roller 28 is rotatable relative to the additional bush 30. When the bicycle chain 10 is mounted on the bicycle A, the roller 22 and the additional roller 28 come into contact with the sprocket teeth.

[0035] The bushing 24 is configured to be inserted into the first inner link hole 32A and the third inner link hole 40A when the bicycle chain 10 is assembled. The pin 20 is configured to pass through the bushing hole 24A when the bicycle chain 10 is assembled. The bushing 24 is cylindrical in shape. The bushing 24 has a first end face 24B, a second end face 24C, and an outer peripheral face 24D. The first end face 24B is a face facing the first outer link face 16A of the first outer link plate 16 in the first inner link axial direction DA. Preferably, the first end face 24B is configured to be flush with the second inner link face 12B at the first peripheral portion 32B of the first inner link end portion 32 of the first inner link plate 12. The second end face 24C is a face facing the third outer link face 18A of the second outer link plate 18 in the second inner link axial direction DB. Preferably, the second end face 24C is configured to be flush with the fourth inner link face 14B at the third periphery 40B of the third inner link end portion 40 of the second inner link plate 14.

[0036] The additional bushing 30 is configured to be inserted into the second inner link hole 34A and the fourth inner link hole 42A when the bicycle chain 10 is in an assembled state. The additional bushing 30 has a bushing hole 30A. The additional pin 26 is configured to pass through the bushing hole 30A of the additional bushing 30 when the bicycle chain 10 is in an assembled state.

[0037] The shape of the additional bush 30 is the same as that of the bush 24. The additional bush 30 has a first end face 30B, a second end face 30C, and an outer peripheral face 30D. The first end face 30B is a face facing the first outer link face 16A of the first outer link plate 16 in the third inner link axial direction DC. The second end face 30C is a face facing the third outer link face 18A of the second outer link plate 18 in the fourth inner link axial direction DD. Preferably, the first end face 30B is configured to be flush with the second inner link face 12B at the second peripheral portion 34B of the second inner link end portion 34 of the first inner link plate 12. The second end face 30C is configured to be flush with the fourth inner link face 14B at the fourth peripheral portion 42B of the fourth inner link end portion 42 of the second inner link plate 14.

[0038] The bicycle chain 10 includes a first sliding surface having a first hardness of 1000HV or more, and a second sliding surface configured to contact the first sliding surface when the bicycle chain 10 is in use. The second sliding surface has a second hardness of 1000HV or more. The first hardness is greater than the second hardness. Specifically, the ratio of the first hardness to the second hardness is 1.2 or more. Preferably, the ratio of the first hardness to the second hardness is 5 or less. The first hardness and the second hardness can be measured by a known method. In one example, the first hardness and the second hardness can be measured by the nanoindentation method of ISO14577 by the International Organization for Standardization.

[0039] When one of the first sliding surface and the second sliding surface is identified as one of the components of the bicycle chain 10, the other of the first sliding surface and the second sliding surface is a component of the bicycle chain 10 that contacts the identified component of the bicycle chain 10. In this embodiment, the first hardness of the first sliding surface and the second hardness of the second sliding surface differ depending on the surface treatment. The first surface treatment is applied to the first sliding surface. The second surface treatment is applied to the second sliding surface. The first surface treatment is different from the second surface treatment. In one example, vanadizing is used as the first surface treatment. Chromizing is used as the second surface treatment. A first surface treatment layer is formed on the first sliding surface by the first surface treatment. A second surface treatment layer is formed on the second sliding surface by the second surface treatment. The film thickness of the first surface treatment layer and the film thickness of the second surface treatment layer are each 1 μm or more and 100 μm or less, and preferably 2 μm or more and 20 μm or less. When vanadizing is used as the first surface treatment, the coating species of the first surface treatment layer contains vanadium carbide (VC).When chromizing is used as the second surface treatment, the coating species of the second surface treatment layer contains chromium (Cr).

[0040] When the first sliding surface and the second sliding surface are formed partially on the components of the bicycle chain 10, the portions other than the portions constituting the first sliding surface and the second sliding surface are masked. The first surface treatment layer and the second surface treatment layer are not formed on the masked portions. The first surface treatment layer is formed on the unmasked portions constituting the first sliding surface. The second surface treatment layer is formed on the unmasked portions constituting the second sliding surface.

[0041] The following describes the parts of bicycle chain 10 where components slide against each other when bicycle chain 10 is in use. The first inner link plate 12 slides against the first outer link plate 16, the roller 22, and the additional roller 28. More specifically, the second inner link surface 12B at the first outer peripheral portion 32C of the first inner link end portion 32 of the first inner link plate 12 slides against the first outer link surface 16A at the first outer link end portion 48 of the first outer link plate 16. The first inner link surface 12A at the first inner link end portion 32 slides against the first end surface 22B of the roller 22. The first inner link surface 12A at the second inner link end portion 34 slides against the first end surface 28B of the additional roller 28.

[0042] The second inner link plate 14 slides against the second outer link plate 18, the roller 22, and the additional roller 28. More specifically, the fourth inner link surface 14B at the third outer circumferential portion 40C of the third inner link end portion 40 of the second inner link plate 14 slides against the third outer link surface 18A at the third outer link end portion 54 of the second outer link plate 18. The third inner link surface 14A at the third inner link end portion 40 slides against the second end surface 22C of the roller 22. The third inner link surface 14A at the fourth inner link end portion 42 slides against the second end surface 28C of the additional roller 28.

[0043] The bushing 24 slides with the pin 20 and the roller 22. More specifically, the bushing hole 24A of the bushing 24 slides with the outer peripheral surface 20A of the pin 20. The outer peripheral surface 24D of the bushing 24 slides with the roller hole 22A of the roller 22.

[0044] The additional bush 30 slides with the additional pin 26 and the additional roller 28. More specifically, a bush hole 30A of the additional bush 30 slides with an outer circumferential surface 26A of the additional pin 26. An outer circumferential surface 30D of the additional bush 30 slides with a roller hole 28A of the additional roller 28.

[0045] Next, the relationship between the first and second sliding surfaces and the components of the bicycle chain 10 will be explained. Below, examples of combinations of the first and second sliding surfaces and the components of the bicycle chain 10 are shown. The first to sixth examples of combinations may be combined with each other as long as no technical contradiction occurs. Figure 6 shows a list of the relationships between the first and second sliding surfaces and the components of the bicycle chain 10.

[0046] In a first example, one of the first sliding surface and the second sliding surface is formed on the first inner link plate 12, and the other of the first sliding surface and the second sliding surface is formed on at least one of the first outer link plate 16 and the rollers 22. In one example, the first sliding surface is formed on the first inner link plate 12, and the second sliding surface is formed on at least one of the first outer link plate 16 and the rollers 22. In another example, the second sliding surface is formed on the first inner link plate 12, and the first sliding surface is formed on at least one of the first outer link plate 16 and the rollers 22.

[0047] In the first example, the first sliding surface or the second sliding surface of the first inner link plate 12 is formed on at least one of the second inner link surface 12B at the first outer periphery 32C of the first inner link end portion 32, the second inner link surface 12B at the second outer periphery 34C of the second inner link end portion 34, and the first inner link surface 12A of the first inner link end portion 32. The first sliding surface or the second sliding surface of the first outer link plate 16 is formed on at least one of the first outer link surface 16A at the first outer link end portion 48 and the first outer link surface 16A at the second outer link end portion 50. The first sliding surface or the second sliding surface of the roller 22 is formed on the first end surface 22B.

[0048] In a second example, one of the first and second sliding surfaces is formed on the bushing 24, and the other of the first and second sliding surfaces is formed on at least one of the pin 20 and the roller 22. In one example, the first sliding surface is formed on the bushing 24, and the second sliding surface is formed on at least one of the pin 20 and the roller 22. In another example, the second sliding surface is formed on the bushing 24, and the first sliding surface is formed on at least one of the pin 20 and the roller 22.

[0049] In the second example, the first sliding surface or the second sliding surface of the bush 24 is formed on at least one of the bush hole 24A and the outer peripheral surface 24D of the bush 24. The first sliding surface or the second sliding surface of the pin 20 is formed on the outer peripheral surface 20A of the pin 20. The first sliding surface or the second sliding surface of the roller 22 is formed in the roller hole 22A.

[0050] In a third example, one of the first sliding surface and the second sliding surface is formed on the first inner link plate 12, and the other of the first sliding surface and the second sliding surface is formed on the additional roller 28. In one example, the first sliding surface is formed on the first inner link plate 12, and the second sliding surface is formed on the additional roller 28. In another example, the second sliding surface is formed on the first inner link plate 12, and the first sliding surface is formed on the additional roller 28.

[0051] In the third example, the first sliding surface or the second sliding surface of the first inner link plate 12 is formed on the second inner link surface 12B of the second inner link end portion 34. The first sliding surface or the second sliding surface of the additional roller 28 is formed on the first end surface 28B of the additional roller 28.

[0052] In a fourth example, one of the first sliding surface and the second sliding surface is formed on the additional bushing 30, and the other of the first sliding surface and the second sliding surface is formed on at least one of the additional pin 26 and the additional roller 28. In one example, the first sliding surface is formed on the additional bushing 30, and the second sliding surface is formed on at least one of the additional pin 26 and the additional roller 28. In another example, the second sliding surface is formed on the additional bushing 30, and the first sliding surface is formed on at least one of the additional pin 26 and the additional roller 28.

[0053] In the fourth example, the first sliding surface or the second sliding surface of the additional bush 30 is formed on at least one of the bush hole 30A and the outer circumferential surface 30D of the additional bush 30. The first sliding surface or the second sliding surface of the additional pin 26 is formed on the outer circumferential surface 26A of the additional pin 26. The first sliding surface or the second sliding surface of the additional roller 28 is formed in the roller hole 28A.

[0054] In a fifth example, one of the first sliding surface and the second sliding surface is formed on the second inner link plate 14, and the other of the first sliding surface and the second sliding surface is formed on at least one of the second outer link plate 18 and the rollers 22. In one example, the first sliding surface is formed on the second inner link plate 14, and the second sliding surface is formed on at least one of the second outer link plate 18 and the rollers 22. In another example, the second sliding surface is formed on the second inner link plate 14, and the first sliding surface is formed on at least one of the second outer link plate 18 and the rollers 22.

[0055] In the fifth example, the first or second sliding surface of the second inner link plate 14 is formed on at least one of the fourth inner link surface 14B at the third outer periphery 40C of the third inner link end portion 40, the fourth inner link surface 14B at the fourth outer periphery 42C of the fourth inner link end portion 42, and the third inner link surface 14A at the third inner link end portion 40. The first or second sliding surface of the second outer link plate 18 is formed on at least one of the third outer link surface 18A at the third outer link end portion 54 and the third outer link surface 18A at the fourth outer link end portion 56. The first or second sliding surface of the roller 22 is formed on the second end surface 22C of the roller 22.

[0056] In a sixth example, one of the first sliding surface and the second sliding surface is formed on the second inner link plate 14, and the other of the first sliding surface and the second sliding surface is formed on the additional roller 28. In one example, the first sliding surface is formed on the second inner link plate 14, and the second sliding surface is formed on the additional roller 28. In another example, the second sliding surface is formed on the second inner link plate 14, and the first sliding surface is formed on the additional roller 28.

[0057] In the sixth example, the first sliding surface or the second sliding surface of the second inner link plate 14 is formed on the third inner link surface 14A of the fourth inner link end portion 42. The first sliding surface or the second sliding surface of the additional roller 28 is formed on the second end surface 28C of the additional roller 28.

[0058] The area where the first surface treatment or the second surface treatment is applied to the first inner link plate 12 can be changed arbitrarily. The first surface treatment or the second surface treatment may be applied to the entire surface of the first inner link plate 12, or may be applied to a part of the surface of the first inner link plate 12. The first surface treatment or the second surface treatment may be applied to a portion of the first inner link plate 12 that contacts at least one of the first outer link plate 16, the roller 22, and the additional roller 28. In one example, the first surface treatment or the second surface treatment is applied to the first inner link surface 12A of the first inner link plate 12. The first surface treatment or the second surface treatment is applied to at least the first inner link end portion 32 and the second inner link end portion 34 of the first inner link surface 12A. In one example, the first surface treatment or the second surface treatment is applied to the second inner link surface 12B of the first inner link plate 12. The first surface treatment or the second surface treatment is applied to at least the first inner link end portion 32 and the second inner link end portion 34 of the second inner link surface 12B. The first surface treatment or the second surface treatment is applied to at least the first outer periphery portion 32C of the first inner link end portion 32 and the second outer periphery portion 34C of the second inner link end portion 34 of the second inner link surface 12B.

[0059] The area where the first surface treatment or the second surface treatment is applied to the second inner link plate 14 can be changed arbitrarily. The first surface treatment or the second surface treatment may be applied to the entire surface of the second inner link plate 14, or may be applied to a part of the surface of the second inner link plate 14. The first surface treatment or the second surface treatment is applied to at least a portion of the second inner link plate 14 that contacts at least one of the second outer link plate 18, the roller 22, and the additional roller 28. In one example, the first surface treatment or the second surface treatment is applied to the third inner link surface 14A of the second inner link plate 14. The first surface treatment or the second surface treatment is applied to at least the third inner link end portion 40 and the fourth inner link end portion 42 of the third inner link surface 14A. In one example, the first surface treatment or the second surface treatment is applied to the fourth inner link surface 14B of the second inner link plate 14. The first surface treatment or the second surface treatment is applied to at least the third inner link end portion 40 and the fourth inner link end portion 42 of the fourth inner link surface 14B. The first surface treatment or the second surface treatment is applied to at least the third outer periphery portion 40C of the third inner link end portion 40 and the fourth outer periphery portion 42C of the fourth inner link end portion 42 of the fourth inner link surface 14B.

[0060] The area of ​​the first outer link plate 16 to which the first surface treatment or the second surface treatment is applied can be changed as desired. The first surface treatment and the second surface treatment may be applied to the entire surface of the first outer link plate 16, or may be applied to a portion of the surface of the first outer link plate 16. The first surface treatment or the second surface treatment is applied to at least a portion of the first outer link plate 16 that comes into contact with the first inner link plate 12. In one example, the first surface treatment or the second surface treatment is applied to the first outer link surface 16A of the first outer link plate 16. The first surface treatment or the second surface treatment is applied to at least the first outer link end portion 48 and the second outer link end portion 50 of the first outer link surface 16A.

[0061] The area of ​​the second outer link plate 18 to which the first surface treatment or the second surface treatment is applied can be changed as desired. The first surface treatment and the second surface treatment may be applied to the entire surface of the second outer link plate 18, or may be applied to a portion of the surface of the second outer link plate 18. The first surface treatment or the second surface treatment is applied to at least a portion of the second outer link plate 18 that comes into contact with the second inner link plate 14. In one example, the first surface treatment or the second surface treatment is applied to the third outer link surface 18A of the second outer link plate 18. The first surface treatment or the second surface treatment is applied to at least the third outer link end portion 54 and the fourth outer link end portion 56 of the third outer link surface 18A.

[0062] The range of the pin 20 to which the first surface treatment or the second surface treatment is applied can be changed as desired. The first surface treatment and the second surface treatment may be applied to the entire surface of the pin 20, or may be applied to part of the surface of the pin 20. The first surface treatment or the second surface treatment is applied to at least the portion of the pin 20 that comes into contact with the bush 24. In one example, the first surface treatment or the second surface treatment is applied to the entire outer circumferential surface 20A of the pin 20.

[0063] The range of the additional pin 26 to which the first surface treatment or the second surface treatment is applied can be changed arbitrarily. The first surface treatment and the second surface treatment may be applied to the entire surface of the additional pin 26, or may be applied to part of the surface of the additional pin 26. The first surface treatment or the second surface treatment is applied to at least a portion of the additional pin 26 that comes into contact with the additional bushing 30. In one example, the first surface treatment or the second surface treatment is applied to the entire outer circumferential surface 26A of the additional pin 26.

[0064] The area of ​​the roller 22 to which the first surface treatment or the second surface treatment is applied can be changed as desired. The first surface treatment and the second surface treatment may be applied to the entire surface of the roller 22, or may be applied to part of the surface of the roller 22. In one example, the first surface treatment or the second surface treatment is applied to at least one of the roller hole 22A, the first end face 22B, and the second end face 22C of the roller 22.

[0065] The range in which the first surface treatment or the second surface treatment is applied to the additional roller 28 can be changed as desired. The first surface treatment or the second surface treatment may be applied to the entire surface of the additional roller 28, or may be applied to part of the surface of the additional roller 28. In one example, the first surface treatment or the second surface treatment is applied to at least one of the roller hole 28A, the first end face 28B, and the second end face 28C of the additional roller 28.

[0066] The area of ​​the bushing 24 to which the first surface treatment or the second surface treatment is applied can be changed as desired. The first surface treatment and the second surface treatment may be applied to the entire surface of the bushing 24, or may be applied to part of the surface of the bushing 24. In one example, the first surface treatment or the second surface treatment is applied to at least one of the bushing hole 24A and the outer circumferential surface 24D of the bushing 24.

[0067] The area to which the first surface treatment or the second surface treatment is applied in the additional bushing 30 can be changed as desired. The first surface treatment and the second surface treatment may be applied to the entire surface of the additional bushing 30, or may be applied to part of the surface of the additional bushing 30. In one example, the first surface treatment or the second surface treatment is applied to at least one of the bush hole 30A and the outer circumferential surface 30D of the additional bushing 30.

[0068] <Second embodiment> A bicycle chain 10 of the second embodiment will be described with reference to Figures 7 and 8. The bicycle chain 10 of this embodiment differs from the bicycle chain 10 of the first embodiment mainly in that the bushing 24 is omitted. In the following description, components common to the bicycle chain 10 of the first embodiment are given the same reference numerals and their description will be omitted.

[0069] As shown in Fig. 7, the first inner link end portion 32 of the first inner link plate 12 includes a first annular axial protrusion 60 that circumferentially surrounds the first inner link hole 32A with respect to the first inner link central axis AX1. The second inner link end portion 34 of the first inner link plate 12 includes a second annular axial protrusion 62 that circumferentially surrounds the second inner link hole 34A with respect to the second inner link central axis AX2. For example, the first annular axial protrusion 60 is formed integrally with the first inner link end portion 32 by burring. The second annular axial protrusion 62 is formed integrally with the second inner link end portion 34 by burring.

[0070] The third inner link end portion 40 of the second inner link plate 14 includes a third annular axial protrusion 64 that circumferentially surrounds the third inner link hole 40A about the third inner link central axis AX3. The fourth inner link end portion 42 of the second inner link plate 14 includes a fourth annular axial protrusion 66 that circumferentially surrounds the fourth inner link hole 42A about the fourth inner link central axis AX4. For example, the third annular axial protrusion 64 is formed integrally with the third inner link end portion 40 by burring. The fourth annular axial protrusion 66 is formed integrally with the fourth inner link end portion 42 by burring.

[0071] The pin 20 is configured to be inserted through the first outer link hole 48A and the third outer link hole 54A and pass through the first inner link hole 32A and the third inner link hole 40A when the bicycle chain 10 is in an assembled state. Preferably, the pin 20 is press-fit into the first outer link hole 48A and the third outer link hole 54A when the bicycle chain 10 is in an assembled state. The first annular axial projection 60 and the third annular axial projection 64 are configured to be adjacent to the outer circumferential surface 20A of the pin 20. The pin 20 is rotatable relative to the first annular axial projection 60 and the third annular axial projection 64.

[0072] The roller 22 is disposed between the first inner link end portion 32 of the first inner link plate 12 and the third inner link end portion 40 of the second inner link plate 14. The first annular axial protrusion 60 and the third annular axial protrusion 64 are inserted into the roller hole 22A of the roller 22. The roller 22 is rotatable relative to the first annular axial protrusion 60 and the third annular axial protrusion 64.

[0073] The additional pin 26 is configured to be inserted through the second outer link hole 50A and the fourth outer link hole 56A and pass through the second inner link hole 34A and the fourth inner link hole 42A when the bicycle chain 10 is in an assembled state. Preferably, the additional pin 26 is press-fit into the second outer link hole 50A and the fourth outer link hole 56A when the bicycle chain 10 is in an assembled state. The second annular axial protrusion 62 and the fourth annular axial protrusion 66 are configured to be adjacent to the outer circumferential surface 26A of the additional pin 26. The additional pin 26 is rotatable relative to the second annular axial protrusion 62 and the fourth annular axial protrusion 66.

[0074] The additional roller 28 is disposed between the second inner link end portion 34 of the first inner link plate 12 and the fourth inner link end portion 42 of the second inner link plate 14. The second annular axial protrusion 62 and the fourth annular axial protrusion 66 are inserted into the roller hole 28A of the additional roller 28. The additional roller 28 is rotatable relative to the second annular axial protrusion 62 and the fourth annular axial protrusion 66.

[0075] The following describes the parts of bicycle chain 10 where components slide against each other when bicycle chain 10 is in use. The first inner link plate 12 slides with the first outer link plate 16, the pin 20, the roller 22, the additional pin 26, and the additional roller 28. More specifically, the second inner link surface 12B at the first outer peripheral portion 32C of the first inner link end portion 32 of the first inner link plate 12 slides with the first outer link surface 16A at the first outer link end portion 48 of the first outer link plate 16. The first inner link hole 32A of the first inner link plate 12 slides with the outer peripheral surface 20A of the pin 20. The first inner link surface 12A at the first inner link end portion 32 slides with the first end surface 22B of the roller 22. The outer peripheral surface 60A of the first annular axial protrusion 60 at the first inner link end portion 32 slides with the roller hole 22A of the roller 22. The second inner link hole 34A of the first inner link plate 12 slides with the outer peripheral surface 26A of the additional pin 26. The first inner link surface 12A of the second inner link end portion 34 slides against the first end surface 28B of the additional roller 28. The outer peripheral surface 62A of the second annular axial protrusion 62 of the second inner link end portion 34 slides against the roller hole 28A of the additional roller 28.

[0076] The second inner link plate 14 slides with the second outer link plate 18, the pin 20, the roller 22, the additional pin 26, and the additional roller 28. More specifically, the fourth inner link surface 14B at the third outer peripheral portion 40C of the third inner link end portion 40 of the second inner link plate 14 slides with the third outer link surface 18A at the third outer link end portion 54 of the second outer link plate 18. The third inner link hole 40A of the second inner link plate 14 slides with the outer peripheral surface 20A of the pin 20. The third inner link surface 14A at the third inner link end portion 40 slides with the second end surface 22C of the roller 22. The outer peripheral surface 64A of the third annular axial protrusion 64 at the third inner link end portion 40 slides with the roller hole 22A of the roller 22. The fourth inner link hole 42A of the second inner link plate 14 slides with the outer peripheral surface 26A of the additional pin 26. The third inner link surface 14A of the fourth inner link end portion 42 slides against the second end surface 28C of the additional roller 28. The outer peripheral surface 66A of the fourth annular axial protrusion 66 of the fourth inner link end portion 42 slides against the roller hole 28A of the additional roller 28.

[0077] Next, the relationship between the first and second sliding surfaces and the components of the bicycle chain 10 will be explained. Below, examples of combinations of the first and second sliding surfaces and the components of the bicycle chain 10 are shown. The first to fourth examples of combinations may be combined with each other as long as no technical contradiction occurs. Figure 8 shows a list of the relationships between the first and second sliding surfaces and the components of the bicycle chain 10.

[0078] In a first example, one of the first sliding surface and the second sliding surface is formed on the first inner link plate 12, and the other of the first sliding surface and the second sliding surface is formed on at least one of the first outer link plate 16, the pin 20, and the roller 22. In one example, the first sliding surface is formed on the first inner link plate 12, and the second sliding surface is formed on at least one of the first outer link plate 16, the pin 20, and the roller 22. In another example, the second sliding surface is formed on the first inner link plate 12, and the first sliding surface is formed on at least one of the first outer link plate 16, the pin 20, and the roller 22.

[0079] In the first example, the first or second sliding surface of the first inner link plate 12 is formed on at least one of the first inner link hole 32A, the outer peripheral surface 60A of the first annular axial protrusion 60, the second inner link surface 12B of the first outer peripheral portion 32C of the first inner link end portion 32, and the first inner link surface 12A of the first inner link end portion 32. The first or second sliding surface of the first outer link plate 16 is formed on the first outer link surface 16A of the first outer link end portion 48. The first or second sliding surface of the pin 20 is formed on the outer peripheral surface 20A of the pin 20. The first or second sliding surface of the roller 22 is formed on at least one of the roller hole 22A and the first end surface 22B.

[0080] In a second example, one of the first and second sliding surfaces is formed on the first inner link plate 12, and the other of the first and second sliding surfaces is formed on at least one of the additional pin 26 and the additional roller 28. In one example, the first sliding surface is formed on the first inner link plate 12, and the second sliding surface is formed on at least one of the additional pin 26 and the additional roller 28. In another example, the second sliding surface is formed on the first inner link plate 12, and the first sliding surface is formed on at least one of the additional pin 26 and the additional roller 28.

[0081] In the second example, the first sliding surface or the second sliding surface of the first inner link plate 12 is formed on at least one of the second inner link hole 34A, the outer peripheral surface 62A of the second annular axial protrusion 62, and the first inner link surface 12A of the second inner link end portion 34. The first sliding surface or the second sliding surface of the additional pin 26 is formed on the outer peripheral surface 26A of the additional pin 26. The first sliding surface or the second sliding surface of the additional roller 28 is formed on at least one of the roller hole 28A and the first end face 28B.

[0082] In a third example, one of the first sliding surface and the second sliding surface is formed on the second inner link plate 14, and the other of the first sliding surface and the second sliding surface is formed on at least one of the second outer link plate 18, the pin 20, and the roller 22. In one example, the first sliding surface is formed on the second inner link plate 14, and the second sliding surface is formed on at least one of the second outer link plate 18, the pin 20, and the roller 22. In another example, the second sliding surface is formed on the second inner link plate 14, and the first sliding surface is formed on at least one of the second outer link plate 18, the pin 20, and the roller 22.

[0083] In the third example, the first sliding surface or the second sliding surface of the second inner link plate 14 is formed on at least one of the third inner link hole 40A, the outer peripheral surface 64A of the third annular axial protrusion 64, and the third inner link surface 14A of the third inner link end portion 40. The first sliding surface or the second sliding surface of the pin 20 is formed on the outer peripheral surface 20A of the pin 20. The first sliding surface or the second sliding surface of the roller 22 is formed on at least one of the roller hole 22A and the second end surface 22C.

[0084] In a fourth example, one of the first sliding surface and the second sliding surface is formed on the second inner link plate 14, and the other of the first sliding surface and the second sliding surface is formed on at least one of the additional pin 26 and the additional roller 28. In one example, the first sliding surface is formed on the second inner link plate 14, and the second sliding surface is formed on at least one of the additional pin 26 and the additional roller 28. In another example, the second sliding surface is formed on the second inner link plate 14, and the first sliding surface is formed on at least one of the additional pin 26 and the additional roller 28.

[0085] In the fourth example, the first or second sliding surface of the second inner link plate 14 is formed on at least one of the fourth inner link hole 42A, the outer peripheral surface 66A of the fourth annular axial protrusion 66, and the third inner link surface 14A of the fourth inner link end portion 42. The first or second sliding surface of the additional pin 26 is formed on the outer peripheral surface 26A of the additional pin 26. The first or second sliding surface of the additional roller 28 is formed on at least one of the roller hole 28A and the second end surface 28C.

[0086] The area of ​​the first inner link plate 12 to which the first surface treatment or the second surface treatment is applied can be changed as desired, as in the first embodiment. The first surface treatment or the second surface treatment in this embodiment may be applied to at least one of the first inner link hole 32A, the second inner link hole 34A, the outer circumferential surface 60A of the first annular axial protrusion 60, and the outer circumferential surface 62A of the second annular axial protrusion 62.

[0087] The area to which the first surface treatment or the second surface treatment is applied in the second inner link plate 14 can be arbitrarily changed, as in the first embodiment. The first surface treatment or the second surface treatment in this embodiment may be applied to at least one of the third inner link hole 40A, the fourth inner link hole 42A, the outer peripheral surface 64A of the third annular axial protrusion 64, and the outer peripheral surface 66A of the fourth annular axial protrusion 66.

[0088] <Third embodiment> A bicycle chain 10 of a third embodiment will be described with reference to FIG. 9. The bicycle chain 10 of this embodiment differs from the bicycle chain 10 of the second embodiment mainly in the components of the bicycle chain 10 that are subjected to different surface treatments. In the following description, components common to the bicycle chain 10 of the second embodiment are given the same reference numerals and their description will be omitted. The bicycle chain 10 of FIG. 9 has the same configuration as the bicycle chain 10 of the second embodiment of FIG. 7.

[0089] As shown in Fig. 9, bicycle chain 10 includes first inner link plate 12, second inner link plate 14, first outer link plate 16, second outer link plate 18, first pin 70, second pin 72, first surface treatment, and second surface treatment. Bicycle chain 10 of this embodiment includes first pin 70 and second pin 72 instead of pin 20 and additional pin 26. First pin 70 is formed from the same material as pin 20 and has the same shape as pin 20. First pin 70 has an outer circumferential surface 70A. Second pin 72 is formed from the same material as additional pin 26 and has the same shape as additional pin 26. Second pin 72 has an outer circumferential surface 72A.

[0090] First pin 70 is configured to be inserted through first outer link hole 48A and third outer link hole 54A, and pass through first inner link hole 32A and third inner link hole 40A, when bicycle chain 10 is in an assembled state. Preferably, first pin 70 is press-fit into first outer link hole 48A and third outer link hole 54A, when bicycle chain 10 is in an assembled state.

[0091] Second pin 72 is configured to be inserted through second outer link hole 50A and fourth outer link hole 56A, and to pass through second inner link hole 34A and fourth inner link hole 42A, when bicycle chain 10 is in an assembled state. Preferably, second pin 72 is press-fit into second outer link hole 50A and fourth outer link hole 56A, when bicycle chain 10 is in an assembled state.

[0092] In the traveling direction SA of the bicycle chain 10, the first inner link hole 32A of the first inner link plate 12 is located forward of the second inner link hole 34A. In the traveling direction SA, the third inner link hole 40A of the second inner link plate 14 is located forward of the fourth inner link hole 42A. The first pin 70 inserted through the first inner link hole 32A and the third inner link hole 40A is located forward of the second pin 72 inserted through the second inner link hole 34A and the fourth inner link hole 42A.

[0093] The bicycle chain 10 of this embodiment further includes a first roller 74 and a second roller 76 instead of the roller 22 and the additional roller 28. The first roller 74 is formed of the same material as the roller 22 and has the same shape as the roller 22. The first roller 74 has a roller hole 74A, a first end face 74B, and a second end face 74C. The roller hole 74A corresponds to the roller hole 22A of the roller 22. The first end face 74B corresponds to the first end face 22B of the roller 22. The second end face 74C corresponds to the second end face 22C of the roller 22. The second roller 76 is formed of the same material as the additional roller 28 and has the same shape as the additional roller 28. The second roller 76 has a roller hole 76A, a first end face 76B, and a second end face 76C. The roller hole 76A corresponds to the roller hole 28A of the additional roller 28. The first end surface 76B corresponds to the first end surface 28B of the additional roller 28. The second end surface 76C corresponds to the second end surface 28C of the additional roller 28.

[0094] In the bicycle chain 10 of this embodiment, a first surface treatment is applied to the front portions of the first inner link plate 12 and the second inner link plate 14 in the running direction SA and the portions that slide with the front portions, and a second surface treatment is applied to the rear portions and the portions that slide with the rear portions. Examples of combinations of portions that are subjected to the first surface treatment and the second surface treatment are described below. The following first to third examples can be combined with each other as long as no technical contradiction occurs.

[0095] In a first example, the first surface treatment is applied to at least one of the first pin 70, the first inner link hole 32A, and the third inner link hole 40A, or the first surface treatment is applied to at least one of the first inner link hole 32A and the second inner link hole 34A. When the first surface treatment is applied to at least one of the first inner link hole 32A and the third inner link hole 40A, the first pin 70 may be applied with a surface treatment different from the first surface treatment.

[0096] When the first surface treatment is applied to at least one of the first pin 70, the first inner link hole 32A, and the third inner link hole 40A, the second surface treatment is applied to at least one of the second pin 72, the second inner link hole 34A, and the fourth inner link hole 42A, or when the first surface treatment is applied to at least one of the first inner link hole 32A and the second inner link hole 34A, the second surface treatment is applied to at least one of the third inner link hole 40A and the fourth inner link hole 42A. When the second surface treatment is applied to at least one of the third inner link hole 40A and the fourth inner link hole 42A, the second pin 72 may be subjected to a surface treatment different from the second surface treatment.

[0097] In the second example, the first surface treatment is applied to at least one of the first roller 74, the first annular axial protrusion 60 of the first inner link end portion 32, the first inner link surface 12A of the first inner link end portion 32, the third annular axial protrusion 64 of the third inner link end portion 40, and the third inner link surface 14A of the third inner link end portion 40. The second surface treatment is applied to at least one of the second roller 76, the second annular axial protrusion 62 of the second inner link end portion 34, the second inner link surface 12B of the second inner link end portion 34, the fourth annular axial protrusion 66 of the fourth inner link end portion 42, and the fourth inner link surface 14B of the fourth inner link end portion 42.

[0098] The first surface treatment may be applied to the entirety or part of the first inner link surface 12A of the first inner link end portion 32. The first surface treatment may be applied to at least the part of the first inner link surface 12A of the first inner link end portion 32 that contacts the first roller 74. The first surface treatment may be applied to the entirety or part of the third inner link surface 14A of the third inner link end portion 40. The first surface treatment may be applied to at least the part of the third inner link surface 14A of the third inner link end portion 40 that contacts the first roller 74. The second surface treatment may be applied to the entirety or part of the first inner link surface 12A of the second inner link end portion 34. The second surface treatment may be applied to at least the part of the second inner link surface 12B of the second inner link end portion 34 that contacts the second roller 76. The second surface treatment may be applied to the entirety or part of the third inner link surface 14A of the fourth inner link end portion 42. The second surface treatment may be applied to at least the portion of the third inner link surface 14A of the fourth inner link end portion 42 that comes into contact with the second roller 76.

[0099] In a third example, the first surface treatment is applied to at least one of the second inner link surface 12B of the first inner link end portion 32, the fourth inner link surface 14B of the third inner link end portion 40, the first outer link surface 16A of the first outer link end portion 48, and the third outer link surface 18A of the third outer link end portion 54. The second surface treatment is applied to at least one of the second inner link surface 12B of the second inner link end portion 34, the fourth inner link surface 14B of the fourth inner link end portion 42, the first outer link surface 16A of the second outer link end portion 50, and the third outer link surface 18A of the fourth outer link end portion 56.

[0100] The first surface treatment may be applied to the entire second inner link surface 12B of the first inner link end portion 32, or may be applied partially. The first surface treatment may be applied at least to a portion of the second inner link surface 12B of the first inner link end portion 32 that contacts with the first outer link end portion 48. The first surface treatment may be applied to the entire fourth inner link surface 14B of the third inner link end portion 40, or may be applied partially. The first surface treatment may be applied at least to a portion of the fourth inner link surface 14B of the third inner link end portion 40 that contacts with the third outer link end portion 54. The first surface treatment may be applied to the entire first outer link surface 16A of the first outer link end portion 48, or may be applied partially. The first surface treatment may be applied at least to a portion of the first outer link surface 16A of the first outer link end portion 48 that contacts with the first inner link end portion 32. The first surface treatment may be applied to the entirety or part of the third outer link surface 18A of the third outer link end portion 54. It is sufficient that the first surface treatment is applied to at least the portion of the third outer link surface 18A of the third outer link end portion 54 that comes into contact with the third inner link end portion 40.

[0101] The second surface treatment may be applied to the entire second inner link surface 12B of the second inner link end portion 34, or may be applied partially. The second surface treatment may be applied at least to a portion of the second inner link surface 12B of the second inner link end portion 34 that contacts the second outer link end portion 50. The second surface treatment may be applied to the entire fourth inner link surface 14B of the fourth inner link end portion 42, or may be applied partially. The second surface treatment may be applied at least to a portion of the fourth inner link surface 14B of the fourth inner link end portion 42 that contacts the fourth outer link end portion 56. The second surface treatment may be applied to the entire first outer link surface 16A of the second outer link end portion 50, or may be applied partially. The second surface treatment may be applied at least to a portion of the first outer link surface 16A of the second outer link end portion 50 that contacts the second inner link end portion 34. The second surface treatment may be applied to the entirety or part of the third outer link surface 18A of the fourth outer link end portion 56. It is sufficient that the second surface treatment is applied to at least the portion of the third outer link surface 18A of the fourth outer link end portion 56 that comes into contact with the fourth inner link end portion 42.

[0102] When the first surface treatment is applied to the first pin 70 and the second surface treatment is applied to the second pin 72, the surface of the first pin 70 has a first hardness of 1000 HV or more and the surface of the second pin 72 has a second hardness of 1000 HV or more. The first hardness of the first pin 70 is greater than the second hardness of the second pin 72. Specifically, the ratio of the first hardness to the second hardness is 1.2 or more. Preferably, the ratio of the first hardness to the second hardness is 5 or less.

[0103] When the first surface treatment is applied to the first inner link hole 32A and the third inner link hole 40A, the first inner link hole 32A and the third inner link hole 40A each have a third hardness of 1000 HV or more. When the second surface treatment is applied to the second inner link hole 34A and the fourth inner link hole 42A, the second inner link hole 34A and the fourth inner link hole 42A each have a fourth hardness of 1000 HV or more. The third hardness of the first inner link hole 32A and the third inner link hole 40A is greater than the fourth hardness of the second inner link hole 34A and the fourth inner link hole 42A. Specifically, the ratio of the third hardness to the fourth hardness is 1.2 or more. Preferably, the ratio of the third hardness to the fourth hardness is 5 or less.

[0104] When the first surface treatment is applied to the first inner link surface 12A of the first inner link end portion 32 and the third inner link surface 14A of the third inner link end portion 40, the first inner link surface 12A of the first inner link end portion 32 and the third inner link surface 14A of the third inner link end portion 40 have a fifth hardness of 1000 HV or more. When the second surface treatment is applied to the first inner link surface 12A of the second inner link end portion 34 and the third inner link surface 14A of the fourth inner link end portion 42, the first inner link surface 12A of the second inner link end portion 34 and the third inner link surface 14A of the fourth inner link end portion 42 have a sixth hardness of 1000 HV or more. The fifth hardness of the first inner link surface 12A of the first inner link end portion 32 and the third inner link surface 14A of the third inner link end portion 40 is greater than the sixth hardness of the first inner link surface 12A of the second inner link end portion 34 and the third inner link surface 14A of the fourth inner link end portion 42. Specifically, the ratio of the fifth hardness to the sixth hardness is 1.2 or more. Preferably, the ratio of the fifth hardness to the sixth hardness is 5 or less.

[0105] When the first surface treatment is applied to the first outer link surface 16A of the first outer link end portion 48 and the third outer link surface 18A of the third outer link end portion 54, the first outer link surface 16A of the first outer link end portion 48 and the third outer link surface 18A of the third outer link end portion 54 have a seventh hardness of 1000 HV or more. When the second surface treatment is applied to the first outer link surface 16A of the second outer link end portion 50 and the third outer link surface 18A of the fourth outer link end portion 56, the first outer link surface 16A of the second outer link end portion 50 and the third outer link surface 18A of the fourth outer link end portion 56 have an eighth hardness of 1000 HV or more. The seventh hardness of the first outer link surface 16A of the first outer link end portion 48 and the third outer link surface 18A of the third outer link end portion 54 is greater than the eighth hardness of the first outer link surface 16A of the second outer link end portion 50 and the third outer link surface 18A of the fourth outer link end portion 56. Specifically, the ratio of the seventh hardness to the eighth hardness is 1.2 or greater. Preferably, the ratio of the seventh hardness to the eighth hardness is 5 or less.

[0106] The first surface treatment is different from the second surface treatment. In this embodiment, vanadizing is used as the first surface treatment. Chromizing is used as the second surface treatment. A first surface treatment layer is formed by the first surface treatment on the surface to be treated with the first surface treatment. A second surface treatment layer is formed by the second surface treatment on the surface to be treated with the second surface treatment. The film thickness of the first surface treatment layer and the film thickness of the second surface treatment layer are each 1 μm or more and 100 μm or less, and preferably 2 μm or more and 20 μm or less.

[0107] The range of the first pin 70 to which the first surface treatment is applied can be changed as desired. The first surface treatment may be applied to the entire surface of the first pin 70, or may be applied to part of the surface of the first pin 70. The first surface treatment may be applied to at least one of the portion of the first pin 70 that contacts the first inner link hole 32A and the portion of the first pin 70 that contacts the third inner link hole 40A. In one example, the first surface treatment is applied to the entire outer circumferential surface 70A of the first pin 70.

[0108] The range of the second pin 72 to which the second surface treatment is applied can be changed as desired. The second surface treatment may be applied to the entire surface of the second pin 72, or may be applied to part of the surface of the second pin 72. The second surface treatment may be applied to at least one of the portion of the second pin 72 that contacts the second inner link hole 34A and the portion of the second pin 72 that contacts the fourth inner link hole 42A. In one example, the second surface treatment is applied to the entire outer circumferential surface 70A of the second pin 72.

[0109] The range of the first roller 74 to which the first surface treatment is applied can be changed arbitrarily. The first surface treatment may be applied to the entire surface of the first roller 74, or may be applied to a portion of the surface of the first roller 74. The first surface treatment may be applied to at least one of the portion of the first roller 74 that contacts the first pin 70, the portion of the first roller 74 that contacts the first inner link end portion 32 of the first inner link plate 12, and the portion of the first roller 74 that contacts the third inner link end portion 40 of the second inner link plate 14. In one example, the first surface treatment is applied to at least one of the roller hole 74A, the first end face 74B, and the second end face 74C of the first roller 74.

[0110] The range of the second roller 76 to which the second surface treatment is applied can be changed arbitrarily. The second surface treatment may be applied to the entire surface of the second roller 76, or may be applied to a portion of the surface of the second roller 76. The second surface treatment may be applied to at least one of the portion of the second roller 76 that contacts the second pin 72, the portion of the second roller 76 that contacts the second inner link end portion 34 of the first inner link plate 12, and the portion of the second roller 76 that contacts the fourth inner link end portion 42 of the second inner link plate 14. In one example, the second surface treatment is applied to at least one of the roller hole 76A, the first end face 76B, and the second end face 76C of the second roller 76.

[0111] <Fourth embodiment> A bicycle chain 10 of the fourth embodiment will be described with reference to Fig. 10. The bicycle chain 10 of this embodiment differs from the bicycle chain 10 of the third embodiment mainly in that a first bushing 78 and a second bushing 80 are added. In the following description, components common to the bicycle chain 10 of the first embodiment are given the same reference numerals and their description will be omitted. The bicycle chain 10 of Fig. 10 has a similar configuration to the bicycle chain 10 of the first embodiment of Fig. 3.

[0112] 10, the first inner link plate 12 of this embodiment is configured such that the first annular axial protrusion 60 is omitted from the first inner link end portion 32, and the second annular axial protrusion 62 is omitted from the second inner link end portion 34. The second inner link plate 14 is configured such that the third annular axial protrusion 64 is omitted from the third inner link end portion 40, and the fourth annular axial protrusion 66 is omitted from the fourth inner link end portion 42.

[0113] The first bushing 78 is configured to be inserted into the first inner link hole 32A and the third inner link hole 40A when the bicycle chain 10 is assembled. Preferably, the first bushing 78 is press-fit into the first inner link hole 32A and the third inner link hole 40A. The first bushing 78 has a bushing hole 78A, a first end face 78B, a second end face 78C, and an outer peripheral surface 78D. The first end face 78B is the face that faces the first outer link plate 16 when the bicycle chain 10 is assembled. The second end face 78C is the face that faces the second outer link plate 18 when the bicycle chain 10 is assembled.

[0114] The second bushing 80 is configured to be inserted into the second inner link hole 34A and the fourth inner link hole 42A when the bicycle chain 10 is in an assembled state. Preferably, the second bushing 80 is press-fitted into the second inner link hole 34A and the fourth inner link hole 42A. The second bushing 80 has a bushing hole 80A, a first end face 80B, a second end face 80C, and an outer peripheral surface 80D. The first end face 80B is the face that faces the first outer link plate 16 when the bicycle chain 10 is in an assembled state. The second end face 80C is the face that faces the second outer link plate 18 when the bicycle chain 10 is in an assembled state.

[0115] Next, examples of combinations of members to be subjected to the first surface treatment and the second surface treatment will be described. The following first to fourth examples can be combined with each other as long as no technical contradiction occurs.

[0116] In a first example, a first surface treatment is applied to at least one of the first pin 70 and the first bushing 78. A second surface treatment is applied to at least one of the second pin 72 and the second bushing 80.

[0117] In a second example, a first surface treatment is applied to at least one of the first roller 74 and the first bushing 78. A second surface treatment is applied to at least one of the second roller 76 and the second bushing 80.

[0118] In a third example, the first surface treatment is applied to at least one of the first inner link surface 12A of the first inner link end portion 32, the third inner link surface 14A of the third inner link end portion 40, and the first roller 74. The second surface treatment is applied to at least one of the first inner link surface 12A of the second inner link end portion 34, the third inner link surface 14A of the fourth inner link end portion 42, and the second roller 76.

[0119] The first surface treatment may be applied to the entirety or part of the first inner link surface 12A of the first inner link end portion 32. The first surface treatment may be applied to at least the part of the first inner link surface 12A of the first inner link end portion 32 that contacts the first roller 74. The first surface treatment may be applied to the entirety or part of the third inner link surface 14A of the third inner link end portion 40. The first surface treatment may be applied to at least the part of the third inner link surface 14A of the third inner link end portion 40 that contacts the first roller 74. The second surface treatment may be applied to the entirety or part of the first inner link surface 12A of the second inner link end portion 34. The second surface treatment may be applied to at least the part of the first inner link surface 12A of the second inner link end portion 34 that contacts the second roller 76. The second surface treatment may be applied to the entirety or part of the third inner link surface 14A of the fourth inner link end portion 42. The second surface treatment may be applied to at least the portion of the third inner link surface 14A of the fourth inner link end portion 42 that comes into contact with the second roller 76.

[0120] In a fourth example, the first surface treatment is applied to at least one of the second inner link surface 12B of the first inner link end portion 32, the fourth inner link surface 14B of the third inner link end portion 40, the first outer link surface 16A of the first outer link end portion 48, and the third outer link surface 18A of the third outer link end portion 54. The second surface treatment is applied to at least one of the second inner link surface 12B of the second inner link end portion 34, the fourth inner link surface 14B of the fourth inner link end portion 42, the first outer link surface 16A of the second outer link end portion 50, and the third outer link surface 18A of the fourth outer link end portion 56.

[0121] In the first and second examples, the area in the first bushing 78 where the first surface treatment is applied can be changed arbitrarily. The first surface treatment may be applied to the entire surface of the first bushing 78, or may be applied to a part of the surface of the first bushing 78. In the first bushing 78 of the first example, the first surface treatment is applied to at least the bushing hole 78A. In the first bushing 78 of the second example, the first surface treatment is applied to at least the outer circumferential surface 78D. In the first bushing 78 of the first and second examples, the first surface treatment is applied to at least one of the bushing hole 78A, the first end face 78B, the second end face 78C, and the outer circumferential surface 78D.

[0122] In the first and second examples, the area in the second bushing 80 where the second surface treatment is applied can be changed arbitrarily. The second surface treatment may be applied to the entire surface of the second bushing 80, or may be applied to a part of the surface of the second bushing 80. In the second bushing 80 of the first example, the second surface treatment is applied to the bushing hole 80A. In the second bushing 80 of the second example, the second surface treatment is applied to the outer circumferential surface 80D. In the second bushing 80 of the first and second examples, the second surface treatment is applied to at least one of the bushing hole 80A, the first end face 80B, the second end face 80C, and the outer circumferential surface 80D.

[0123] <Example of change> The above embodiments are examples of possible forms of the bicycle chain according to the present disclosure, and are not intended to limit the forms. The bicycle chain according to the present disclosure may take forms different from those exemplified in the above embodiments. One example is a form in which part of the configuration of each of the above embodiments is replaced, modified, or omitted, or a form in which a new configuration is added to each of the above embodiments. In the following modified examples, parts that are common to the forms of each of the above embodiments are given the same reference numerals as each of the above embodiments, and their description is omitted.

[0124] In each embodiment, the combination of the first surface treatment and the second surface treatment can be changed as desired. The first surface treatment may be chromizing, and the second surface treatment may be vanadizing. The first surface treatment and the second surface treatment may be other than vanadizing and chromizing, and may be nitriding, sulfurizing nitriding, boronizing, etc. In this case, the first surface treatment layer and the second surface treatment layer are formed of iron nitride (Fe-N), chromium (Cr), titanium nitride (TiN), chromium nitride (CrN), titanium carbide (TiC), titanium carbonitride (TiCN), etc.

[0125] In the first embodiment, the first end surface 24B of the bush 24 may protrude toward the first outer link plate 16 beyond the first peripheral portion 32B of the first inner link end portion 32 of the first inner link plate 12. In one example, the first end surface 24B of the bush 24 is configured to contact the first outer link surface 16A of the first outer link plate 16. In this case, one of the first sliding surface and the second sliding surface is formed on the first outer link plate 16, and the other of the first sliding surface and the second sliding surface is formed on the bush 24. In one example, the first sliding surface is formed on the first outer link plate 16, and the second sliding surface is formed on the bush 24. In another example, the second sliding surface is formed on the first outer link plate 16, and the first sliding surface is formed on the bush 24. The first sliding surface or the second sliding surface on the first outer link plate 16 is formed on the first outer link surface 16A of the first outer link end portion 48. The first sliding surface or the second sliding surface of the bushing 24 is formed on a first end surface 24B of the bushing 24. The first surface treatment or the second surface treatment is performed on the first end surface 24B of the bushing 24.

[0126] In the first embodiment, the second end surface 24C of the bush 24 may protrude toward the second outer link plate 18 beyond the third peripheral portion 40B of the third inner link end portion 40 of the second inner link plate 14. In one example, the second end surface 24C of the bush 24 is configured to contact the third outer link surface 18A of the second outer link plate 18. In this case, one of the first sliding surface and the second sliding surface is formed on the second outer link plate 18, and the other of the first sliding surface and the second sliding surface is formed on the bush 24. In one example, the first sliding surface is formed on the second outer link plate 18, and the second sliding surface is formed on the bush 24. In another example, the second sliding surface is formed on the second outer link plate 18, and the first sliding surface is formed on the bush 24. The first sliding surface or the second sliding surface on the second outer link plate 18 is formed on the third outer link surface 18A of the third outer link end portion 54. The first sliding surface or the second sliding surface of the bushing 24 is formed on the second end surface 24C of the bushing 24. The first surface treatment or the second surface treatment is performed on the second end surface 24C of the bushing 24.

[0127] In the first embodiment, the first end surface 30B of the additional bush 30 may protrude toward the first outer link plate 16 beyond the second peripheral portion 34B of the second inner link end portion 34 of the first inner link plate 12. In one example, the first end surface 30B of the additional bush 30 is configured to contact the first outer link surface 16A of the first outer link plate 16. In this case, one of the first sliding surface and the second sliding surface is formed on the first outer link plate 16, and the other of the first sliding surface and the second sliding surface is formed on the additional bush 30. In one example, the first sliding surface is formed on the first outer link plate 16, and the second sliding surface is formed on the additional bush 30. In another example, the second sliding surface is formed on the first outer link plate 16, and the first sliding surface is formed on the additional bush 30. The first sliding surface or the second sliding surface on the first outer link plate 16 is formed on the first outer link surface 16A of the first outer link end portion 48. The first sliding surface or the second sliding surface of the additional bushing 30 is formed on the first end surface 30B of the additional bushing 30. The first surface treatment or the second surface treatment is performed on the first end surface 30B of the additional bushing 30.

[0128] In the first embodiment, the second end surface 30C of the additional bush 30 may protrude toward the second outer link plate 18 beyond the fourth peripheral portion 42B of the fourth inner link end portion 42 of the second inner link plate 14. In one example, the second end surface 30C of the additional bush 30 is configured to contact the third outer link surface 18A of the second outer link plate 18. In this case, one of the first sliding surface and the second sliding surface is formed on the second outer link plate 18, and the other of the first sliding surface and the second sliding surface is formed on the additional bush 30. In one example, the first sliding surface is formed on the second outer link plate 18, and the second sliding surface is formed on the additional bush 30. In another example, the second sliding surface is formed on the second outer link plate 18, and the first sliding surface is formed on the additional bush 30. The first sliding surface or the second sliding surface on the second outer link plate 18 is formed on the third outer link surface 18A of the fourth outer link end portion 56. The first sliding surface or the second sliding surface of the additional bushing 30 is formed on the second end surface 30C of the additional bushing 30. The first surface treatment or the second surface treatment is performed on the second end surface 30C of the additional bushing 30.

[0129] In each embodiment, as shown in FIG. 11, the second inner link surface 12B at the first peripheral portion 32B of the first inner link end portion 32 of the first inner link plate 12 and the second inner link surface 12B at the first outer peripheral portion 32C may be formed flush with each other. In the first embodiment, when the second inner link surface 12B at the first peripheral portion 32B and the first end surface 24B of the bush 24 are formed flush with each other, the first end surface 24B of the bush 24 slides against the first outer link plate 16. In this case, one of the first sliding surface and the second sliding surface is formed on the first outer link plate 16, and the other of the first sliding surface and the second sliding surface is formed on the bush 24. In one example, the first sliding surface is formed on the first outer link plate 16, and the second sliding surface is formed on the bush 24. In another example, the second sliding surface is formed on the first outer link plate, and the first sliding surface is formed on the bush 24. The first sliding surface or the second sliding surface of the first outer link plate 16 is formed on the first outer link surface 16A of the first outer link end portion 48. The first sliding surface or the second sliding surface of the bushing 24 is formed on the first end surface 24B of the bushing 24. The first surface treatment or the second surface treatment is applied to the first end surface 24B of the bushing 24.

[0130] In each embodiment, as shown in FIG. 11, the second inner link surface 12B at the second peripheral portion 34B of the second inner link end portion 34 of the first inner link plate 12 and the second inner link surface 12B at the second outer peripheral portion 34C may be formed flush with each other. In the first embodiment, when the second inner link surface 12B at the second peripheral portion 34B and the first end surface 30B of the additional bush 30 are configured flush with each other, the first end surface 30B of the additional bush 30 slides against the first outer link plate 16. In this case, one of the first sliding surface and the second sliding surface is formed on the first outer link plate 16, and the other of the first sliding surface and the second sliding surface is formed on the additional bush 30. In one example, the first sliding surface is formed on the first outer link plate 16, and the second sliding surface is formed on the additional bush 30. In another example, the second sliding surface is formed on the first outer link plate 16, and the first sliding surface is formed on the additional bushing 30. The first sliding surface or the second sliding surface on the first outer link plate 16 is formed on the first outer link surface 16A of the second outer link end portion 50. The first sliding surface or the second sliding surface on the additional bushing 30 is formed on the first end surface 30B of the additional bushing 30. The first surface treatment or the second surface treatment is applied to the first end surface 30B of the additional bushing 30.

[0131] In each embodiment, as shown in FIG. 11, the fourth inner link surface 14B at the third peripheral portion 40B of the third inner link end portion 40 of the second inner link plate 14 and the fourth inner link surface 14B at the third outer peripheral portion 40C may be formed flush with each other. In the first embodiment, when the fourth inner link surface 14B at the third peripheral portion 40B and the second end surface 24C of the bush 24 are configured flush with each other, the second end surface 24C of the bush 24 slides against the second outer link plate 18. In this case, one of the first sliding surface and the second sliding surface is formed on the second outer link plate 18, and the other of the first sliding surface and the second sliding surface is formed on the bush 24. In one example, the first sliding surface is formed on the second outer link plate 18, and the second sliding surface is formed on the bush 24. In another example, the second sliding surface is formed on the second outer link plate 18, and the first sliding surface is formed on the bush 24. The first sliding surface or the second sliding surface of the second outer link plate 18 is formed on the third outer link surface 18A of the third outer link end portion 54. The first sliding surface or the second sliding surface of the bushing 24 is formed on the second end surface 24C of the bushing 24. The first surface treatment or the second surface treatment is applied to the second end surface 24C of the bushing 24.

[0132] In each embodiment, as shown in FIG. 11, the fourth inner link surface 14B at the fourth peripheral portion 42B of the fourth inner link end portion 42 of the second inner link plate 14 and the fourth inner link surface 14B at the fourth outer peripheral portion 42C may be formed flush with each other. In the first embodiment, when the fourth inner link surface 14B at the fourth peripheral portion 42B and the second end surface 30C of the additional bush 30 are configured to be flush with each other, the second end surface 30C of the additional bush 30 slides against the second outer link plate 18. In this case, one of the first sliding surface and the second sliding surface is formed on the second outer link plate 18, and the other of the first sliding surface and the second sliding surface is formed on the additional bush 30. In one example, the first sliding surface is formed on the second outer link plate 18, and the second sliding surface is formed on the additional bush 30. In another example, the second sliding surface is formed on the second outer link plate 18, and the first sliding surface is formed on the additional bushing 30. The first sliding surface or the second sliding surface on the second outer link plate 18 is formed on the third outer link surface 18A of the fourth outer link end portion 56. The first sliding surface or the second sliding surface on the additional bushing 30 is formed on the second end surface 30C of the additional bushing 30. The first surface treatment or the second surface treatment is applied to the second end surface 30C of the additional bushing 30. [Explanation of symbols]

[0133] 10...bicycle chain, 12...first inner link plate, 12A...first inner link surface, 12B...second inner link surface, 14...second inner link plate, 14A...third inner link surface, 14B...fourth inner link surface, 16...first outer link plate, 16A...first outer link surface, 16B...second outer link surface, 18...second outer link plate, 18A...third outer link surface, 18B...fourth outer link surface, 20...pin, 22...roller, 24...bush, 24A...bush hole, 32...first inner link end portion, 32A...first inner link hole, 34...second inner link end portion, 34A...second inner link hole, 36...first inner link middle portion, 40...third inner link end portion, 40A...third inner link hole, 42...fourth inner link end portion, 42A...fourth inner link hole, 44...second inner link intermediate portion, 48...first outer link end portion, 48A...first outer link hole, 50...second outer link end portion, 50A...second outer link hole, 52...first outer link intermediate portion, 54...third outer link end portion, 54A...third outer link hole, 56...fourth outer link end portion, 56A...fourth outer link hole, 58...second outer link intermediate portion, 70...first pin, 72...second pin, AX1...first inner link central axis, AX2...second inner link central axis, AX3...third inner link central axis, AX4...fourth inner link central axis, BX1...first outer link central axis, BX2...second outer link central axis, BX3...third outer link central axis, BX4...fourth outer link central axis, DA...first inner link axial direction, DB...second inner link axial direction, DE...first outer link axial direction, DF...second outer link axial direction.

Claims

1. A bicycle chain, comprising: The bicycle chain comprises: With a pinch of salt, a bush having a bush hole; The pin is inserted into the bush when the bicycle chain is in an assembled state, the bicycle chain comprises a first sliding surface having a first hardness of 1000 HV or greater, and a second sliding surface configured to contact the first sliding surface during use of the bicycle chain; The second sliding surface has a second hardness of 1000 HV or more, and a ratio of the first hardness to the second hardness is 1.2 or more; The first sliding surface is formed at least on a surface of the bush that slides against the pin, and the second sliding surface is formed at least on the pin. Bicycle chain.

2. A bicycle chain, comprising: The bicycle chain comprises: With a pinch of salt, an inner link plate; the pin is inserted into the inner link plate when the bicycle chain is in an assembled state; the bicycle chain comprises a first sliding surface having a first hardness of 1000 HV or greater, and a second sliding surface configured to contact the first sliding surface during use of the bicycle chain; The second sliding surface has a second hardness of 1000 HV or more, and a ratio of the first hardness to the second hardness is 1.2 or more; The first sliding surface is formed on a surface of the inner link plate that slides against the pin, and the second sliding surface is formed on at least the pin. Bicycle chain.

3. A bicycle chain, comprising: The bicycle chain comprises: an inner link plate; an outer link plate adjacent to the inner link plate; and a roller; the bicycle chain comprises a first sliding surface having a first hardness of 1000 HV or greater, and a second sliding surface configured to contact the first sliding surface during use of the bicycle chain; The second sliding surface has a second hardness of 1000 HV or more, and a ratio of the first hardness to the second hardness is 1.2 or more; one of the first sliding surface and the second sliding surface is formed on the inner link plate, and the other of the first sliding surface and the second sliding surface is formed on at least one of the outer link plate and the roller; Bicycle chain.

4. A bicycle chain, comprising: The bicycle chain comprises: With a pinch of salt, a bush having a bush hole, an inner link plate, an outer link plate adjacent to the inner link plate, and a roller; The pin is inserted into the bush when the bicycle chain is in an assembled state, The bushing is configured to be inserted into the inner link plate when the bicycle chain is in an assembled state, the bicycle chain comprises a first sliding surface having a first hardness of 1000 HV or greater, and a second sliding surface configured to contact the first sliding surface during use of the bicycle chain; The second sliding surface has a second hardness of 1000 HV or more, and a ratio of the first hardness to the second hardness is 1.2 or more; one of the first sliding surface and the second sliding surface is formed on the bush, and the other of the first sliding surface and the second sliding surface is formed on at least one of the outer link plate and the roller; Bicycle chain.

5. The bicycle chain further comprises an inner link plate, an outer link plate, and a roller; the inner link plates include a first inner link plate and a second inner link plate, the outer link plates include a first outer link plate and a second outer link plate, The first inner link plate is a first inner link end portion including a first inner link hole having a first inner link central axis; a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis; a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion; A first inner link surface; a second inner link surface disposed on an opposite side of the first inner link surface in a first inner link axial direction with respect to a central axis of the first inner link, The second inner link plate is a third inner link end portion including a third inner link hole having a third inner link central axis; a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the third inner link central axis; a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion; a third inner link surface that faces the first inner link surface of the first inner link plate in an axial direction of the first inner link when the bicycle chain is in an assembled state; a fourth inner link surface disposed on an opposite side of the third inner link surface in a second inner link axial direction with respect to the third inner link central axis, The first outer link plate is a first inner link plate adjacent to the first inner link plate in an assembled state of the bicycle chain without sandwiching another inner link plate or another outer link plate therebetween; a first outer link end portion including a first outer link hole having a first outer link central axis; a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis; a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion; A first outer link surface; a second outer link surface disposed on an opposite side to the first outer link surface in a first outer link axial direction relative to a central axis of the first outer link, The second outer link plate is When the bicycle chain is assembled, the second inner link plate is adjacent to the second inner link plate without sandwiching another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; a third outer link surface that faces the first outer link surface of the first outer link plate in the first outer link axial direction when the bicycle chain is in an assembled state; a fourth outer link surface disposed on an opposite side to the third outer link surface in a second outer link axial direction relative to a central axis of the third outer link, the bushing is configured to be inserted into the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state; 2. The bicycle chain of claim 1, wherein said roller is configured to be located between said first inner link surface of said first inner link plate and said third inner link surface of said second inner link plate in an assembled state of said bicycle chain.

6. The bicycle chain further comprises an outer link plate and a roller. the inner link plates include a first inner link plate and a second inner link plate, the outer link plates include a first outer link plate and a second outer link plate, The first inner link plate is a first inner link end portion including a first inner link hole having a first inner link central axis; a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis; a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion; A first inner link surface; a second inner link surface disposed on an opposite side of the first inner link surface in a first inner link axial direction with respect to a central axis of the first inner link, The second inner link plate is a third inner link end portion including a third inner link hole having a third inner link central axis; a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the third inner link central axis; a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion; a third inner link surface that faces the first inner link surface of the first inner link plate in an axial direction of the first inner link when the bicycle chain is in an assembled state; a fourth inner link surface disposed on an opposite side of the third inner link surface in a second inner link axial direction with respect to the third inner link central axis, The first outer link plate is a first inner link plate adjacent to the first inner link plate in an assembled state of the bicycle chain without sandwiching another inner link plate or another outer link plate therebetween; a first outer link end portion including a first outer link hole having a first outer link central axis; a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis; a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion; A first outer link surface; a second outer link surface disposed on an opposite side to the first outer link surface in a first outer link axial direction relative to a central axis of the first outer link, The second outer link plate is When the bicycle chain is assembled, the second inner link plate is adjacent to the second inner link plate without sandwiching another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; a third outer link surface that faces the first outer link surface of the first outer link plate in the first outer link axial direction when the bicycle chain is in an assembled state; a fourth outer link surface disposed on an opposite side to the third outer link surface in a second outer link axial direction relative to a central axis of the third outer link, the pin is configured to be inserted through the first outer link hole and the third outer link hole and pass through the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state; 3. The bicycle chain of claim 2, wherein said roller is configured to be located between said first inner link surface of said first inner link plate and said third inner link surface of said second inner link plate in an assembled state of said bicycle chain.

7. The bicycle chain further comprises a pin; the inner link plates include a first inner link plate and a second inner link plate, the outer link plates include a first outer link plate and a second outer link plate, The first inner link plate is a first inner link end portion including a first inner link hole having a first inner link central axis; a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis; a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion; A first inner link surface; a second inner link surface disposed on an opposite side of the first inner link surface in a first inner link axial direction with respect to a central axis of the first inner link, The second inner link plate is a third inner link end portion including a third inner link hole having a third inner link central axis; a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the third inner link central axis; a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion; a third inner link surface configured to face the first inner link surface of the first inner link plate in an axial direction of the first inner link in an assembled state of the bicycle chain; a fourth inner link surface disposed on an opposite side of the third inner link surface in a second inner link axial direction with respect to the third inner link central axis, The first outer link plate is a first inner link plate adjacent to the first inner link plate in an assembled state of the bicycle chain without sandwiching another inner link plate or another outer link plate therebetween; a first outer link end portion including a first outer link hole having a first outer link central axis; a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis; a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion; A first outer link surface; a second outer link surface disposed on an opposite side to the first outer link surface in a first outer link axial direction relative to a central axis of the first outer link, The second outer link plate is When the bicycle chain is assembled, the second inner link plate is adjacent to the second inner link plate without sandwiching another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; a third outer link surface that faces the first outer link surface of the first outer link plate in the first outer link axial direction when the bicycle chain is in an assembled state; a fourth outer link surface disposed on an opposite side to the third outer link surface in a second outer link axial direction relative to a central axis of the third outer link, the pin is configured to be inserted through the first outer link hole and the third outer link hole and pass through the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state; 4. The bicycle chain of claim 3, wherein said roller is configured to be located between said first inner link surface of said first inner link plate and said third inner link surface of said second inner link plate in an assembled state of said bicycle chain.

8. the inner link plates include a first inner link plate and a second inner link plate, the outer link plates include a first outer link plate and a second outer link plate, The first inner link plate is a first inner link end portion including a first inner link hole having a first inner link central axis; a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis; a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion; A first inner link surface; a second inner link surface disposed on an opposite side of the first inner link surface in a first inner link axial direction with respect to a central axis of the first inner link, The second inner link plate is a third inner link end portion including a third inner link hole having a third inner link central axis; a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the third inner link central axis; a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion; a third inner link surface that faces the first inner link surface of the first inner link plate in an axial direction of the first inner link when the bicycle chain is in an assembled state; a fourth inner link surface disposed on an opposite side of the third inner link surface in a second inner link axial direction with respect to the third inner link central axis, The first outer link plate is a first inner link plate adjacent to the first inner link plate in an assembled state of the bicycle chain without sandwiching another inner link plate or another outer link plate therebetween; a first outer link end portion including a first outer link hole having a first outer link central axis; a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis; a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion; A first outer link surface; a second outer link surface disposed on an opposite side to the first outer link surface in a first outer link axial direction relative to a central axis of the first outer link, The second outer link plate is When the bicycle chain is assembled, the second inner link plate is adjacent to the second inner link plate without sandwiching another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; a third outer link surface that faces the first outer link surface of the first outer link plate in the first outer link axial direction when the bicycle chain is in an assembled state; a fourth outer link surface disposed on an opposite side to the third outer link surface in a second outer link axial direction relative to a central axis of the third outer link, the bushing is configured to be inserted into the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state; 5. The bicycle chain of claim 4, wherein said roller is configured to be located between said first inner link surface of said first inner link plate and said third inner link surface of said second inner link plate in an assembled state of said bicycle chain.

9. The bicycle chain further comprises a bush having a bush hole.

4. A bicycle chain as claimed in claim 3.

10. a bushing having a bushing hole; the bushing is configured to be inserted into the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state; 8. The bicycle chain of claim 7, wherein said pin is configured to pass through said bushing hole in an assembled state of said bicycle chain.

11. 11. The bicycle chain according to claim 1, wherein a ratio of the first hardness to the second hardness is 5 or less.

12. A first surface treatment is applied to the first sliding surface, A second surface treatment is applied to the second sliding surface, 12. The bicycle chain according to claim 1, wherein the first surface treatment is different from the second surface treatment.

13. A first surface treatment is applied to the first sliding surface, A second surface treatment is applied to the second sliding surface, and the second surface treatment is applied only to a portion of the pin that contacts the bush; 6. The bicycle chain of claim 1 or 5, wherein the first surface treatment is different from the second surface treatment.

14. A first surface treatment is applied to the first sliding surface, A second surface treatment is applied to the second sliding surface, and the first surface treatment or the second surface treatment is applied only to a portion of the pin that comes into contact with the inner link plate; 7. The bicycle chain of claim 2 or 6, wherein said first surface treatment is different from said second surface treatment.

15. A first surface treatment is applied to the first sliding surface, A second surface treatment is applied to the second sliding surface, the first surface treatment or the second surface treatment is applied only to a portion of the inner link plate which contacts at least one of the outer link plate and the roller; 11. The bicycle chain of claim 3, 7, 9, or 10, wherein the first surface treatment is different from the second surface treatment.

16. A first surface treatment is applied to the first sliding surface, A second surface treatment is applied to the second sliding surface, the first surface treatment or the second surface treatment is applied only to a portion of the bush that comes into contact with at least one of the outer link plate and the roller; 9. The bicycle chain of claim 4 or claim 8, wherein the first surface treatment is different from the second surface treatment.

17. A bicycle chain, comprising: a first inner link plate, a second inner link plate, a first outer link plate, a second outer link plate, a first pin, a second pin, a first surface treatment, and a second surface treatment, The first inner link plate is a first inner link end portion including a first inner link hole having a first inner link central axis; a second inner link end portion including a second inner link hole having a second inner link central axis extending parallel to the first inner link central axis; a first inner link intermediate portion connecting the first inner link end portion and the second inner link end portion; A first inner link surface; a second inner link surface disposed on an opposite side of the first inner link surface in a first inner link axial direction with respect to a central axis of the first inner link, The second inner link plate is a third inner link end portion including a third inner link hole having a third inner link central axis; a fourth inner link end portion including a fourth inner link hole having a fourth inner link central axis extending parallel to the third inner link central axis; a second inner link intermediate portion connecting the third inner link end portion and the fourth inner link end portion; a third inner link surface configured to face the first inner link surface of the first inner link plate in an axial direction of the first inner link in an assembled state of the bicycle chain; a fourth inner link surface disposed on an opposite side of the third inner link surface in a second inner link axial direction with respect to the third inner link central axis, The first outer link plate is a first inner link plate adjacent to the first inner link plate in an assembled state of the bicycle chain without sandwiching another inner link plate or another outer link plate therebetween; a first outer link end portion including a first outer link hole having a first outer link central axis; a second outer link end portion including a second outer link hole having a second outer link central axis extending parallel to the first outer link central axis; a first outer link intermediate portion connecting the first outer link end portion and the second outer link end portion; A first outer link surface; a second outer link surface disposed on an opposite side to the first outer link surface in a first outer link axial direction relative to a central axis of the first outer link, The second outer link plate is When the bicycle chain is assembled, the second inner link plate is adjacent to the second inner link plate without sandwiching another inner link plate or another outer link plate therebetween; a third outer link end portion including a third outer link hole having a third outer link central axis; a fourth outer link end portion including a fourth outer link hole having a fourth outer link central axis extending parallel to the third outer link central axis; a second outer link intermediate portion connecting the third outer link end portion and the fourth outer link end portion; a third outer link surface that faces the first outer link surface of the first outer link plate in the first outer link axial direction when the bicycle chain is in an assembled state; a fourth outer link surface disposed on an opposite side to the third outer link surface in a second outer link axial direction relative to a central axis of the third outer link, the first pin is configured to be inserted through the first outer link hole and the third outer link hole and pass through the first inner link hole and the third inner link hole when the bicycle chain is in an assembled state; the second pin is configured to be inserted through the second outer link hole and the fourth outer link hole and pass through the second inner link hole and the fourth inner link hole when the bicycle chain is in an assembled state; the first surface treatment is applied to at least one of the first pin, the first inner link hole, and the third inner link hole, or the first surface treatment is applied to at least one of the first inner link hole and the second inner link hole; The first surface treatment is different from the second surface treatment, When the first surface treatment is applied to the first inner link hole, the second surface treatment is applied to at least the second inner link hole; A bicycle chain, wherein when the first surface treatment is applied to the third inner link hole, the second surface treatment is applied to at least the fourth inner link hole.

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