TWI910109B - bicycle chain - Google Patents

Abstract

This invention suppresses the decrease in efficiency of the front and rear sprockets of a bicycle or suppresses the slack in a bicycle chain. A bicycle chain has a plurality of inner link plates, a plurality of outer link plates, and a plurality of pins, said pins being included in part or all of their outer peripheral surfaces, having a pin-hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride.

Description

bicycle chain

This disclosure relates to a bicycle chain.

Patent document 1 discloses a technology for a bicycle chain. The chain of patent document 1 has alternating outer and inner links, connected at their respective ends by rivets. [Prior Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent Application Publication No. 2017-105438

[Problem to be Solved by the Invention] From the viewpoint of suppressing the decrease in efficiency of the front and rear sprockets of a bicycle, or suppressing the loosening of the bicycle chain, it is preferable that at least one of the parts that slide against each other during the use of the bicycle chain has high wear resistance. [Means of Solving the Problem]

The bicycle chain of the first feature disclosed herein is a bicycle chain comprising multiple inner link plates, multiple outer link plates, and multiple pins, wherein the multiple pins are included on a portion or all of their outer peripheral surfaces and have a pin-hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride. According to the bicycle chain of the first feature, the pin-hardened layer improves the wear resistance of the pins, suppresses chain elongation, and enhances drive efficiency.

In the bicycle chain of the second feature disclosed herein, the pin-hardened layer has a sliding surface hardness of 1000 HV or higher and 3500 HV or lower. According to the bicycle chain of the second feature, compared to those with a sliding surface hardness of the pin-hardened layer outside the aforementioned range, the wear resistance of the pin is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the third feature disclosed herein, the plurality of inner link plates have inner link sliding surfaces that slide against the outer peripheral surface of the pin, and the hardness of the sliding surface of the pin hardened layer is greater than the surface hardness of the inner link sliding surface. According to the bicycle chain of the third feature, compared to a chain where the hardness of the sliding surface of the pin hardened layer is less than the surface hardness of the inner link sliding surface, the wear resistance of the pin is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the fourth feature disclosed herein, the plurality of inner link plates have an inner link sliding surface that slides against the outer peripheral surface of the pin, and a portion or all of the inner link sliding surface has a link hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride. According to the bicycle chain of the fourth feature, compared to a chain chain without a link hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride, the wear resistance of the pin is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the fifth feature disclosed herein, the plurality of inner link plates have inner link sliding surfaces that slide against the outer peripheral surface of the pin, and the surface roughness of the pin-hardened layer is smaller than the surface roughness of the inner link sliding surfaces. According to the bicycle chain of the fifth feature, compared to a pin-hardened layer with a surface roughness greater than or equal to that of the inner link sliding surfaces, the wear resistance of the pin is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the sixth feature disclosed herein, the plurality of pins includes a connecting pin for connecting the chain into an endless shape, the surface condition of which is formed differently from that of the other pins. According to the bicycle chain of the sixth feature, only the connecting pin wears more than the other pins. Over prolonged use, the chain gap before and after the connecting pin becomes larger than that of the other pins, producing a clicking sensation or sound during use. Therefore, this can be used to judge the elongation of the chain by the user.

In the bicycle chain of the seventh feature disclosed herein, the plurality of inner link plates include a first inner link plate and a second inner link plate, the plurality of outer link plates include a first outer link plate and a second outer link plate, and the plurality of pins include a first pin. The first inner link plate includes: a first inner link end, including a first inner link opening having a central axis of the first inner link, and a first annular axial protrusion surrounding the first inner link opening in a circumferential direction with respect to the central axis of the first inner link; and a second inner link end, including a second inner link extending parallel to the central axis of the first inner link. The second inner link has a central axis opening and a second annular axial protrusion that surrounds the opening in the circumferential direction with respect to the central axis of the second inner link; a middle portion of the first inner link connects the end of the first inner link and the end of the second inner link; a first inner link surface; and a second inner link surface, disposed on the opposite side of the first inner link surface in the axial direction with respect to the central axis of the first inner link; the first annular axial protrusion has a first proximal end and a first distal end connected to the first inner link surface, and the second annular axial protrusion has... The second inner link plate has a second proximal end and a second distal end connected to the first inner link surface. The second inner link plate includes: a third inner link end portion comprising a third inner link opening having a central axis of the third inner link, and a third annular axial protrusion surrounding the third inner link opening in a circumferential direction with respect to the central axis of the third inner link; and a fourth inner link end portion comprising a fourth inner link opening having a central axis of the fourth inner link extending parallel to the central axis of the third inner link, and a fourth annular axial protrusion surrounding the fourth inner link opening in a circumferential direction with respect to the central axis of the fourth inner link. The bicycle chain has a protruding portion; a second inner link middle portion connecting the end of the third inner link and the end of the fourth inner link; a third inner link face, configured such that, in the assembled state of the bicycle chain, it faces the first inner link face of the first inner link plate in the axial direction of the first inner link; and a fourth inner link face, disposed on the opposite side of the third inner link face in the axial direction of the second inner link about the central axis of the third inner link; the third annular axial protrusion has a third proximal end and a third distal end connected to the third inner link face, the third distal end being positioned such that... In the assembled state of the bicycle chain, the first distal end of the first annular axial protrusion faces the first annular axial protrusion. The fourth annular axial protrusion has a fourth proximal end and a fourth distal end connected to the third inner link surface. The fourth distal end is arranged in the assembled state of the bicycle chain to face the second distal end of the second annular axial protrusion. The first outer link plate is configured to be adjacent to the first inner link plate in the assembled state of the bicycle chain without passing through other inner link plates or other outer link plates. The first outer link plate includes: a first outer link end portion including a first outer link opening having a central axis of the first outer link; a second outer link end portion including a second outer link opening having a central axis of the second outer link extending parallel to the central axis of the first outer link; a middle portion of the first outer link connecting the first outer link end portion and the second outer link end portion; a first outer link face; and a second outer link face, disposed on the opposite side of the first outer link face in a first outer link axial direction about the central axis of the first outer link; the second outer link plate is used in the assembly of the bicycle chain. In the assembled state, the second outer link plate is configured to be adjacent to the second inner link plate without being connected by other inner link plates or other outer link plates. The second outer link plate includes: a third outer link end, including a third outer link opening having a third outer link central axis; a fourth outer link end, including a fourth outer link opening having a fourth outer link central axis extending parallel to the central axis of the third outer link; a second outer link middle portion, connecting the third outer link end and the fourth outer link end; and a third outer link face, which, in the assembled state of the bicycle chain, faces the first outer link axial direction. The chain is configured such that it is aligned with the first outer link surface of the first outer link plate; and a fourth outer link surface is disposed on the opposite side of the third outer link surface in the direction of the second outer link axis about the central axis of the third outer link; the first pin is configured to be inserted into the openings of the first outer link, the third outer link, the first inner link, and the third inner link in the assembled state of the bicycle chain, and has a first outer peripheral surface that slides against the first annular axial protrusion and the third annular axial protrusion in the use state of the bicycle chain. The bicycle chain according to the seventh feature, comprising a first inner link plate, a second inner link plate, a first outer link plate, a second outer link plate, and a first pin, exhibits improved wear resistance, suppressed chain elongation, and improved drive efficiency.

In the bicycle chain of the eighth feature disclosed herein, the plurality of pins includes a second pin, which, in the assembled state of the bicycle chain, is inserted into the openings of the second outer link, the fourth outer link, the second inner link, and the fourth inner link. The second pin has a second outer peripheral surface that slides against the second and fourth annular axial protrusions in the use state of the bicycle chain. According to the bicycle chain of the eighth feature, the wear resistance of the bicycle chain including the second pin is improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the ninth feature disclosed herein, the first proximal end of the first axially oriented annular protrusion is integrally connected to the first inner link surface by a single material, and the second proximal end of the second axially oriented annular protrusion is integrally connected to the first inner link surface by a single material. Compared to bicycle chains not integrally connected by a single material, the bicycle chain according to the ninth feature exhibits further improved wear resistance, suppressed chain elongation, and improved drive efficiency.

In the bicycle chain of the tenth feature disclosed herein, the first inner link plate has a first inner link sliding surface, which is formed on the inner peripheral surface of the opening of the first inner link and the inner peripheral surface of the first annular axial protrusion, extends parallel to the central axis of the first inner link, and slides against the first outer peripheral surface of the first pin. The second inner link plate has a second inner link sliding surface, which is formed on the inner peripheral surface of the opening of the third inner link and the inner peripheral surface of the third annular axial protrusion, extends parallel to the central axis of the third inner link, and slides against the first outer peripheral surface of the first pin. According to the tenth feature, the bicycle chain having a first inner link sliding surface and a second inner link sliding surface has improved wear resistance, suppressed chain elongation, and improved drive efficiency.

In the bicycle chain of the eleventh feature disclosed herein, the sliding surface of the first inner link has a first axial sliding surface length of 0.5 mm or more and 3.5 mm or less in the axial direction of the first inner link, and the sliding surface of the second inner link has a second axial sliding surface length of 0.5 mm or more and 3.5 mm or less in the axial direction of the second inner link. According to the bicycle chain of the eleventh feature, compared with those where the lengths of the first and second axial sliding surfaces are outside the aforementioned ranges, wear resistance is further improved, chain elongation is suppressed, and drive efficiency is improved. Furthermore, compared to the lengths of the first axial sliding surface and the second axial sliding surface being outside the aforementioned range, this achieves smooth engagement between the inner link plate of the bicycle chain and the sprocket teeth of the bicycle sprocket, as well as smooth gear shifting between adjacent bicycle sprockets.

In the bicycle chain of the twelfth feature disclosed herein, the sliding surface of the first inner link has a first inner link sliding surface hardness of 200 HV or higher and 2500 HV or lower, and the sliding surface of the second inner link has a second inner link sliding surface hardness of 200 HV or higher and 2500 HV or lower. According to the bicycle chain of the twelfth feature, compared to those with first and second inner link sliding surface hardness outside the stated range, wear resistance is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the thirteenth feature disclosed herein, the first inner link sliding surface has a first axial sliding surface length defined in the axial direction of the first inner link, and the second inner link sliding surface has a second axial sliding surface length defined in the axial direction of the second inner link. In the assembled state of the bicycle chain, the first pin has a first pin center axis, a first pin axial end face, a second pin axial end face, and a first shaft body. The first shaft body is related to the... In the first pin direction of the first pin center axis, the chain extends between the end face of the first pin direction and the end face of the second pin direction. The length in the first pin direction is defined by the distance between the end faces of the first and second pin directions. The ratio of the length in the first pin direction to the length of the sliding surface in the first axial direction is 2 or more and 7 or less, and the ratio of the length in the first pin direction to the length of the sliding surface in the second axial direction is also 2 or more and 7 or less. According to the thirteenth feature of the bicycle chain, compared to those chains where the ratio of the length in the first pin direction to the length of the sliding surface in the first axial direction and the ratio of the length in the first pin direction to the length of the sliding surface in the second axial direction are outside the aforementioned ranges, wear resistance is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the fourteenth feature disclosed herein, the ratio of the length in the first pin direction to the length of the sliding surface in the first axial direction is 3.5 or more and 6 or less, and the ratio of the length in the first pin direction to the length of the sliding surface in the second axial direction is 3.5 or more and 6 or less. According to the bicycle chain of the fourteenth feature, compared to those where the ratios of the length in the first pin direction to the length of the sliding surface in the first axial direction and the ratios of the length in the first pin direction to the length of the sliding surface in the second axial direction are outside the aforementioned ranges, wear resistance is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the fifteenth feature disclosed herein, the first annular axial protrusion has a first radial thickness defined radially about the central axis of the first inner link, the third annular axial protrusion has a second radial thickness defined radially about the central axis of the third inner link, and the first pin, in the assembled state of the bicycle chain, has a first pin central axis, a first pin axial end face, a second pin axial end face, and a first shaft body. A shaft extends along a first pin direction about the axis of the first pin center, between a first pin direction end face and a second pin direction end face. The length in the first pin direction is defined by the distance between the first pin direction end face and the second pin direction end face. The ratio of the first pin direction length to the first radial thickness is 6 or more and 20 or less, and the ratio of the first pin direction length to the second radial thickness is also 6 or more and 20 or less. According to the fifteenth feature of the bicycle chain, compared to those chains where the ratio of the first pin direction length to the first radial thickness is outside the stated range, wear resistance is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the sixteenth feature disclosed herein, the ratio of the length in the first pin direction to the first radial thickness is 8 or more and 15 or less, and the ratio of the length in the first pin direction to the second radial thickness is 8 or more and 15 or less. According to the bicycle chain of the sixteenth feature, compared to those where the ratio of the length in the first pin direction to the first radial thickness or the ratio of the length in the first pin direction to the first radial thickness is outside the stated range, wear resistance is further improved, chain elongation is suppressed, and drive efficiency is improved.

In the bicycle chain of the seventeenth feature disclosed herein, the first pin, in the assembled state of the bicycle chain, has a first pin center axis, a first pin axis direction end face, a second pin axis direction end face, and a first shaft body, wherein the first shaft body extends in the first pin axis direction about the first pin center axis between the first pin axis direction end face and the second pin axis direction end face. According to the seventeenth feature, in the assembled state, the bicycle chain having a first pin center axis, a first pin direction end face, a second pin direction end face, and a first shaft has improved wear resistance, suppressed chain elongation, and improved drive efficiency. The first shaft extends in the first pin direction about the first pin center axis between the first pin direction end face and the second pin direction end face.

In the bicycle chain of the eighteenth feature disclosed herein, a first locking portion is formed around the entire circumference of the end face in the direction of the first pin, and a second locking portion is formed around the entire circumference of the end face in the direction of the second pin in the direction of the first pin. According to the bicycle chain of the eighteenth feature, the wear resistance of the bicycle chain having the first locking portion and the second locking portion is improved, chain elongation is suppressed, and drive efficiency is improved. The strength of the bicycle chain is also improved by means of the first locking portion and the second locking portion.

In the bicycle chain of the nineteenth feature disclosed herein, the first locking portion is formed around the entire circumference of the end face in the direction of the first pin by a riveting step, and the second locking portion is formed around the entire circumference of the end face in the direction of the second pin by a riveting step. According to the bicycle chain of the nineteenth feature, the wear resistance of the bicycle chain having the first locking portion and the second locking portion formed by the riveting step is improved, chain elongation is suppressed, and drive efficiency is improved. Because the first locking portion and the second locking portion are formed by the riveting step, the manufacturing efficiency of the bicycle chain is excellent.

In the bicycle chain of the twentieth feature disclosed herein, the first pin-direction end face is located on the same plane as the second outer link face, or in the first pin direction about the center axis of the first pin, between the first and second outer link faces; the second pin-direction end face is located on the same plane as the fourth outer link face, or in the first pin direction about the center axis of the first pin, between the third and fourth outer link faces. According to the bicycle chain of the twentieth feature, the wear resistance of the bicycle chain with the first and second pin-direction end faces located at the aforementioned positions is improved, chain elongation is suppressed, and drive efficiency is improved. Furthermore, according to the twentieth feature of the bicycle chain, since the first pin direction end face and the second pin direction end face are located at the aforementioned positions, the speed change operation of the bicycle chain between adjacent bicycle sprockets can be smoothly carried out, and the bicycle chain is miniaturized in the pin direction, thereby increasing the number of sprockets on the bicycle rear sprocket.

In the bicycle chain of the twenty-first feature disclosed herein, the first pin, in the assembled state, is inserted into the openings of the first and third outer links in a press-in state. According to the bicycle chain of the twenty-first feature, the wear resistance of the bicycle chain is improved, chain elongation is suppressed, and drive efficiency is improved because the first pin is inserted into the openings of the first and third outer links in a press-in state.

In the bicycle chain of the twenty-second feature disclosed herein, the first inner link plate has a first inner link recess formed from the first inner link surface toward the second inner link surface, at least in the middle portion of the first inner link; and the second inner link plate has a second inner link recess formed from the third inner link surface toward the fourth inner link surface, at least in the middle portion of the second inner link. According to the bicycle chain of the twenty-second feature, the wear resistance of the bicycle chain having the first inner link recess and the second inner link recess is improved, chain elongation is suppressed, and drive efficiency is improved. Because it has a first inner link recess and a second inner link recess, even if the bicycle chain is miniaturized in the pin direction, the sprocket teeth of the bicycle sprocket can still smoothly engage with the inner link plate.

In the bicycle chain of the twenty-third feature disclosed herein, the second inner link surface at the middle portion of the first inner link is flat, and the fourth inner link surface at the middle portion of the second inner link is flat. According to the bicycle chain of the twenty-third feature, the flat second inner link surface at the middle portion of the first inner link and the flat fourth inner link surface at the middle portion of the second inner link improve wear resistance, suppress chain elongation, and improve drive efficiency. Because the flat second inner link surface at the middle portion of the first inner link and the flat fourth inner link surface at the middle portion of the second inner link enable miniaturization of the bicycle chain in the pin direction, allowing for an increase in the number of sprockets on the bicycle rear sprocket.

In the bicycle chain of the twenty-fourth feature disclosed herein, a first inner link opening recess is formed around the first inner link opening in the second inner link face, a second inner link opening recess is formed around the second inner link opening in the second inner link face, a third inner link opening recess is formed around the third inner link opening in the fourth inner link face, and a fourth inner link opening recess is formed around the fourth inner link opening in the fourth inner link face. According to the bicycle chain of the twenty-fourth feature, the wear resistance of the bicycle chain with the first, second, third, and fourth inner link opening recesses is improved, chain elongation is suppressed, and drive efficiency is improved. By forming a first inner link opening recess, a second inner link opening recess, a third inner link opening recess, and a fourth inner link opening recess, excessive interference between the inner link plate and the outer link plate is suppressed.

In the bicycle chain of the twenty-fifth feature disclosed herein, the first inner link end of the first inner link plate has a first inner link sprocket tooth retaining portion, the first inner link sprocket tooth retaining portion being configured to retain the sprocket tooth when the bicycle chain is engaged with the sprocket tooth of the bicycle sprocket, and the second inner link end of the first inner link plate has a second inner link. The second inner link sprocket tooth retaining portion is configured to retain the sprocket teeth when the bicycle chain is engaged with the sprocket teeth of the bicycle sprocket. A first inner link chamfer is formed on the first inner link surface of the first inner link sprocket tooth retaining portion, and a second inner link chamfer is formed on the first inner link surface of the second inner link sprocket tooth retaining portion. According to the twenty-fifth feature, the bicycle chain having a first inner link sprocket tooth retaining portion, a second inner link sprocket tooth retaining portion, and forming a first inner link chamfered portion and a second inner link chamfered portion, exhibits improved wear resistance, suppressed chain elongation, and improved drive efficiency. With the first inner link chamfered portion and the second inner link chamfered portion, the bicycle chain easily engages with the sprocket teeth of the bicycle sprocket while the sprocket teeth of the bicycle sprocket are held in place by the first inner link sprocket tooth retaining portion and the second inner link sprocket tooth retaining portion.

In the bicycle chain of the twenty-sixth feature disclosed herein, the third inner link end of the second inner link plate has a third inner link sprocket tooth retaining portion, the third inner link sprocket tooth retaining portion being configured to retain the sprocket tooth when the bicycle chain is engaged with the sprocket tooth of the bicycle sprocket, and the fourth inner link end of the second inner link plate has a fourth inner link. The fourth inner link sprocket tooth retaining portion is configured to retain the sprocket teeth when the bicycle chain is engaged with the sprocket teeth of the bicycle sprocket. A third inner link chamfer is formed on the third inner link surface of the third inner link sprocket tooth retaining portion, and a fourth inner link chamfer is formed on the third inner link surface of the fourth inner link sprocket tooth retaining portion. The fourth inner link sprocket tooth retaining portion includes a sprocket tooth retaining portion and a sprocket tooth retaining portion. According to the twenty-sixth feature, the bicycle chain having a third inner link sprocket tooth retaining portion, a fourth inner link sprocket tooth retaining portion, and forming a third inner link chamfered portion and a fourth inner link chamfered portion, exhibits improved wear resistance, suppressed chain elongation, and improved drive efficiency. With the third inner link chamfered portion and the fourth inner link chamfered portion, the bicycle chain easily engages with the sprocket teeth of the bicycle sprocket while the sprocket teeth of the bicycle sprocket are held in place by the third inner link sprocket tooth retaining portion and the fourth inner link sprocket tooth retaining portion.

In the bicycle chain of the twenty-seventh feature disclosed herein, the plurality of pins includes those having through holes extending along their longitudinal direction. According to the bicycle chain of the twenty-seventh feature, the wear resistance of the bicycle chain with through holes is improved, chain elongation is suppressed, and drive efficiency is improved. The bicycle chain is lightweight by forming through holes. [Effects of the Invention]

The bicycle chain disclosed herein exhibits excellent wear resistance, suppressed chain elongation, and improved drive efficiency.

Referring to Figure 1, a bicycle using a bicycle chain will be described. Figure 1 shows a schematic diagram of the transmission system 101 as viewed from above. The transmission system 101 is chain-driven. The transmission system 101 includes a bicycle crank assembly 102, a bicycle sprocket (hereinafter referred to as "sprocket"), and a bicycle chain 100. The sprocket has sprocket teeth that engage with the bicycle chain 100. The sprocket includes a front sprocket 103 and a rear sprocket 104. The bicycle crank assembly 102 includes a crankshaft 105 rotatably supported by the bicycle frame, and a pair of crank arms 106 respectively disposed at both ends of the crankshaft 105. Pedals are rotatably mounted at the front end of each crank arm 106.

The front sprocket 103 is mounted on the crankshaft 105 in a manner that allows it to rotate integrally with the crankshaft 105. The rear sprocket 104 is mounted on the hub of the rear wheel. A bicycle chain 100 is wound around the front sprocket 103 and the rear sprocket 104. The driving force applied to the pedals by the bicycle rider is transmitted to the rear wheel via the crank arm 106, crankshaft 105, front sprocket 103, bicycle chain 100, and rear sprocket 104.

Referring to Figures 2 to 9, the detailed configuration of a bicycle chain 100 according to one embodiment of the present invention will be described. Furthermore, in this embodiment, each inner link plate, outer link plate, and pin is symmetrical in shape along the long side of the bicycle chain 100, and the first inner link plate 110 and the second inner link plate 120, and the first outer link plate 130 and the second outer link plate 140 are symmetrical in shape along the width of the bicycle chain 100. Therefore, components not shown in the figures are also described in this text using corresponding symbols. However, in this invention, each inner link plate, outer link plate, and pin may also have an asymmetrical shape along the long side of the bicycle chain 100, and may also have an asymmetrical shape along the width of the bicycle chain 100. As shown in Figure 2, the bicycle chain 100 includes multiple inner link plates, multiple outer link plates, and multiple pins. The multiple inner link plates include a first inner link plate 110 and a second inner link plate 120. The multiple outer link plates include a first outer link plate 130 and a second outer link plate 140, and the multiple pins include a first pin 150.

As shown in Figures 3, 4, 7, and 8, the first inner link plate 110 includes: a first inner link end 111, comprising a first inner link opening 111A having a central axis A1 of the first inner link, and a first annular axial protrusion 111B surrounding the first inner link opening 111A in the circumferential direction with respect to the central axis A1 of the first inner link; and a second inner link end 112, comprising a second inner link central axis A2 extending parallel to the central axis A1 of the first inner link. The inner link has an opening 112A and a second annular axial protrusion 112B that surrounds the opening 112A in the circumferential direction with respect to the central axis A2 of the second inner link; a middle portion 113 of the first inner link connects the end portion 111 of the first inner link and the end portion 112 of the second inner link; a first inner link surface 114; and a second inner link surface 115, disposed on the opposite side of the first inner link surface 114 in the axial direction DA of the first inner link with respect to the central axis A1 of the first inner link. The first annular axial protrusion 111B has a first proximal end 111BN and a first distal end 111BF connected to the first inner chain joint surface 114, and the second annular axial protrusion 112B has a second proximal end 112BN and a second distal end 112BF connected to the first inner chain joint surface 114.

Similar to the first inner link plate 110, the second inner link plate 120 includes: a third inner link end 121, comprising a third inner link opening 121A having a third inner link central axis A3, and a third annular axial protrusion 121B surrounding the third inner link opening 121A circumferentially with respect to the third inner link central axis A3; a fourth inner link end 122, comprising a fourth inner link opening 122A having a fourth inner link central axis A4 extending parallel to the third inner link central axis A3, and a third annular axial protrusion 121B surrounding the third inner link opening 121A circumferentially with respect to the fourth inner link central axis A4. A fourth annular axial protrusion 122B surrounds the fourth inner link opening 122A upwards; a second inner link middle portion 123 connects the third inner link end 121 and the fourth inner link end 122; a third inner link surface 124 is configured such that, in the assembled state of the bicycle chain 100, it faces the first inner link surface 114 of the first inner link plate 110 in the first inner link axial direction DA; and a fourth inner link surface 125 is disposed on the opposite side of the third inner link surface 124 in the second inner link axial direction DB with respect to the central axis A3 of the third inner link. The third axially oriented protrusion 121B has a third proximal end 121BN and a third distal end 121BF connected to the third inner link surface 124. The third distal end 121BF is arranged facing the first distal end 111BF of the first axially oriented protrusion 111B in the assembled state of the bicycle chain. The fourth axially oriented protrusion 122B has a fourth proximal end 122BN and a fourth distal end 122BF connected to the third inner link surface 124. The fourth distal end 122BF is arranged facing the second distal end 112BF of the second axially oriented protrusion 112B in the assembled state of the bicycle chain 100.

As shown in Figures 3, 5, 7, and 8, the first outer link plate 130 is configured to be adjacent to the first inner link plate 110 without passing through other inner link plates or other outer link plates when the bicycle chain 100 is assembled. The first outer link plate 130 includes: a first outer link end 131, including a first outer link opening 131A having a first outer link central axis B1; a second outer link end 132, including a second outer link opening 132A having a second outer link central axis B2 extending parallel to the first outer link central axis B1; a first outer link middle portion 133 connecting the first outer link end 131 and the second outer link end 132; a first outer link surface 134; and a second outer link surface 135, disposed on the opposite side of the first outer link surface 134 in the first outer link axial direction DE with respect to the first outer link central axis B1.

Similar to the first outer link plate 130, the second outer link plate 140 is configured to be adjacent to the second inner link plate 120 without passing through other inner link plates or other outer link plates when the bicycle chain 100 is assembled. The second outer link plate 140 includes: a third outer link end 141, including a third outer link opening 141A having a third outer link central axis B3; a fourth outer link end 142, including a fourth outer link opening 142A having a fourth outer link central axis B4 extending parallel to the third outer link central axis B3; and a second outer link middle portion 143, connecting the third outer link end 141 and... The fourth outer link end 142; the third outer link face 144, configured such that, in the assembled state of the bicycle chain 100, it faces the first outer link face 134 of the first outer link plate 130 in the axial direction DE of the first outer link; and the fourth outer link face 145, disposed on the opposite side of the third outer link face 144 in the axial direction DF of the second outer link with respect to the central axis B3 of the third outer link.

As shown in Figures 3, 6 to 8, the first pin 150, in the assembled state of the bicycle chain 100, is inserted through the first outer link opening 131A, the third outer link opening 141A, the first inner link opening 111A, and the third inner link opening 121A. It has a first outer peripheral surface 151 that slides against the first annular axial protrusion 111B and the third annular axial protrusion 121B when the bicycle chain 100 is in use. The plurality of pins includes a second pin 160, which, in the assembled state of the bicycle chain 100, is inserted through the second outer link opening 132A, the fourth outer link opening 142A, the second inner link opening 112A, and the fourth inner link opening 122A. The second pin 160 has a second outer peripheral surface 161 that slides against the second circumferential axial protrusion 112B and the fourth circumferential axial protrusion 122B when the bicycle chain 100 is in use. The plurality of pins 150 and 160 have a pin-hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride on part or all of the outer peripheral surfaces 151 and 161. Multiple pins 150 and 160 have through holes 152 and 162 extending along their long sides. The pin hardening layer preferably has a sliding surface hardness of 1000 HV or higher and 3500 HV or lower.

The first proximal end 111BN of the first annular axial protrusion 111B is integrally connected to the first inner link surface 114 by a single material, and the second proximal end 112BN of the second annular axial protrusion 112B is integrally connected to the first inner link surface 114 by a single material. The first inner link plate 110 has a first inner link sliding surface 111C, which is formed on the inner circumferential surface of the first inner link opening 111A and the inner circumferential surface of the first annular axial protrusion 111B, extends parallel to the central axis A1 of the first inner link, and slides against the first outer circumferential surface 151 of the first pin 150. The second inner link plate 120 has a second inner link sliding surface 112C, which is formed on the inner peripheral surface of the third inner link opening 121A and the inner peripheral surface of the third annular axial protrusion 121B. It extends parallel to the central axis A3 of the third inner link and slides with the first outer peripheral surface 151 of the first pin 150.

Preferably, multiple inner link plates 110, 120 have inner link sliding surfaces 111C, 121C, 112C, and 122C that slide against the outer peripheral surfaces 151 and 161 of pins 150 and 160, respectively. The hardness of the sliding surface of the pin-hardened layer is greater than the surface hardness of the inner link sliding surfaces 111C, 121C, 112C, and 122C. The inner link sliding surfaces 111C, 121C, 112C, and 122C may also have a link-hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride, in some or all of them. Preferably, the surface roughness of the pin-hardened layer is smaller than that of the inner link sliding surfaces 111C, 121C, 112C, and 122C. The plurality of pins may also include a connecting pin for connecting the chain into an endless shape, and the surface condition of the connecting pin is formed in a manner different from that of the other pins 150 and 160.

As shown in Figure 9, the sliding surface 111C of the first inner link preferably has a first axial sliding surface length LL1 of 0.5 mm to 3.5 mm along the axial direction DA of the first inner link. The sliding surface 112C of the second inner link preferably has a second axial sliding surface length LL2 of 0.5 mm to 3.5 mm along the axial direction DB of the second inner link. The sliding surface 111C of the first inner link preferably has a first inner link sliding surface hardness of 200 HV to 2500 HV. The sliding surface 112C of the second inner link preferably has a second inner link sliding surface hardness of 200 HV to 2500 HV.

As shown in Figure 9, the first inner link sliding surface 111C has a first axial sliding surface length LL1 defined in the first inner link axial direction DA, and the second inner link sliding surface 112C has a second axial sliding surface length LL2 defined in the second inner link axial direction DB. In the assembled state of the bicycle chain 100, the first pin 150 has a first pin center axis P1, a first pin axial direction end face 153, a second pin axial direction end face 154, and a first shaft 155. The first shaft 155 extends between the first pin axial direction end face 153 and the second pin axial direction end face 154 in the first pin axial direction DP with respect to the first pin center axis P1. The first pin-direction length LP1, along the first pin-direction DP, is defined between the first pin-direction end face 153 and the second pin-direction end face 154. The ratio of the first pin-direction length LP1 to the first axial-direction sliding surface length LL1 is preferably 2 or more and 7 or less, more preferably 3.5 or more and 6 or less. The ratio of the first pin-direction length LP1 to the second axial-direction sliding surface length LL2 is preferably 2 or more and 7 or less, more preferably 3.5 or more and 6 or less. As shown in Figure 10, the third inner link sliding surface 121C has a third axial-direction sliding surface length LL3 defined along the third inner link axial direction DC, and the fourth inner link sliding surface 122C has a fourth axial-direction sliding surface length LL4 defined along the fourth inner link axial direction DD. In the assembled state of the bicycle chain 100, the second pin 160 has a second pin center axis P2, a third pin direction end face 163, a fourth pin direction end face 164, and a second shaft 165. The second shaft 165 extends along the second pin direction DP2 with respect to the second pin center axis P2, between the third pin direction end face 163 and the fourth pin direction end face 164. The second pin direction length LP2 is defined along the second pin direction DP2 by the distance between the third pin direction end face 163 and the fourth pin direction end face 164. Preferably, the ratio of the second pin direction length LP2 to the third pin direction sliding surface length LL3 is 2 or more and 7 or less, more preferably 3.5 or more and 6 or less. The ratio of the length LP2 in the second pin direction to the length LL4 in the fourth axis direction is preferably 2 or more and 7 or less, and more preferably 3.5 or more and 6 or less.

As shown in Figure 9, the first annular axial protrusion 111B has a first radial thickness WL1 defined radially about the central axis A1 of the first inner link, and the third annular axial protrusion 121B has a second radial thickness WL2 defined radially about the central axis A3 of the third inner link. The first pin length LP1 is defined in the first pin direction by the distance between the first pin end face 153 and the second pin end face 154. The ratio of the first pin length LP1 to the first radial thickness WL1 is preferably 6 or more and 20 or less, more preferably 8 or more and 15 or less. The ratio of the first pin length LP1 to the second radial thickness WL2 is preferably 6 or more and 20 or less, more preferably 8 or more and 15 or less. As shown in Figure 10, the second annular axial protrusion 112B has a third radial thickness WL3 defined radially about the central axis A2 of the second inner link. Similarly, like the third annular axial protrusion 121B, the fourth annular axial protrusion 122B has a fourth radial thickness WL4 defined radially about the central axis A4 of the fourth inner link. The second pin axial length LP2, along the second pin axial direction DP2, is defined between the third pin axial direction end face 163 and the fourth pin axial direction end face 164. The ratio of the second pin axial length LP2 to the third radial thickness WL3 is preferably 6 or more and 20 or less, more preferably 8 or more and 15 or less. The ratio of the second pin shaft length LP2 to the fourth radial thickness WL4 is preferably 6 or more and 20 or less, and more preferably 8 or more and 15 or less.

As shown in Figure 8, a first locking portion 156 is formed around the entire circumference of the first pin direction end face 153 in the first pin direction, and a second locking portion 157 is formed around the entire circumference of the second pin direction end face 154 in the first pin direction. The first locking portion 156 is formed around the entire circumference of the first pin direction end face 153 by a riveting step, and the second locking portion 157 is formed around the entire circumference of the second pin direction end face 154 by a riveting step.

The first pin-axis end face 153 is located on the same plane relative to the second outer link face 135, or on the first pin-axis direction DP with respect to the first pin center axis P1, between the first outer link face 134 and the second outer link face 135. The second pin-axis end face 154 is located on the same plane relative to the fourth outer link face 145, or as shown in Figure 8, on the first pin-axis direction DP with respect to the first pin center axis P1, between the third outer link face 144 and the fourth outer link face 145. Preferably, the first pin 150, in the assembled state of the bicycle chain 100, is inserted into the first outer link opening 131A and the third outer link opening 141A in a pressed-in state. Preferably, the second pin 160 is inserted into the second outer link opening 132A and the fourth outer link opening 142A in the assembled state of the bicycle chain 100.

The first inner link plate 110 has a first inner link recess 116 formed at least in the middle portion 113 of the first inner link, extending from the first inner link surface 114 toward the second inner link surface 115. The second inner link plate 120 has a second inner link recess 126 formed at least in the middle portion 123 of the second inner link, extending from the third inner link surface 124 toward the fourth inner link surface 125. The second inner link surface 115 of the middle portion 113 of the first inner link is flat, and the fourth inner link surface 125 of the middle portion 123 of the second inner link is also flat. A first inner link opening recess 111D is formed around the first inner link opening 111A in the second inner link surface 115, and a second inner link opening recess 112D is formed around the second inner link opening 112A in the second inner link surface 115. A third inner link opening recess 121D is formed around the third inner link opening 121A in the fourth inner link surface 125, and a fourth inner link opening recess is formed around the fourth inner link opening 122A in the fourth inner link surface 125.

The first inner link end 111 of the first inner link plate 110 has a first inner link sprocket tooth retaining portion 111E, which is configured to retain the sprocket tooth when the bicycle chain 100 is engaged with the sprocket tooth of the bicycle sprocket. The second inner link end 112 of the first inner link plate 110 has a second inner link sprocket tooth retaining portion 112E, which is configured to retain the sprocket tooth when the bicycle chain 100 is engaged with the sprocket tooth of the bicycle sprocket. A first inner link chamfer 117 is formed on the first inner link surface 114 of the first inner link sprocket tooth holding portion 111E, and a second inner link chamfer 118 is formed on the first inner link surface 114 of the second inner link sprocket tooth holding portion 112E.

The third inner link end 121 of the second inner link plate 120 has a third inner link sprocket tooth retaining portion 121E, which is configured to retain the sprocket tooth when the bicycle chain 100 is engaged with the sprocket tooth of the bicycle sprocket. The fourth inner link end 122 of the second inner link plate 120 has a fourth inner link sprocket tooth retaining portion 122E, which is configured to retain the sprocket tooth when the bicycle chain 100 is engaged with the sprocket tooth of the bicycle sprocket. A third inner link chamfer 127 is formed on the third inner link surface 124 of the third inner link sprocket tooth holding portion 121E, and a fourth inner link chamfer 128 is formed on the third inner link surface 124 of the fourth inner link sprocket tooth holding portion 122E.

The first outer link plate 130 and the second outer link plate 140 are joined by the first pin 150 and the second pin 160. The first inner link plate 110 and the second inner link plate 120 are joined by the first pin 150 and the second pin 160. The assembly of the first inner link plate 110 and the second inner link plate 120 is rotatably connected to the assembly of the first outer link plate 130 and the second outer link plate 140, with the central axes of the first pin 150 and the second pin 160 as its centers. The assemblies of the first inner link plate 110 and the second inner link plate 120, and the assemblies of the first outer link plate 130 and the second outer link plate 140, are alternately arranged and connected in a ring shape.

The roller 170, in the assembled state of the bicycle chain 100, is positioned between the first inner link surface 114 of the first inner link plate 110 and the third inner link surface 124 of the second inner link plate 120. The roller 170 is disposed between the first inner link end 111 of the first inner link plate 110 and the third inner link end 121 of the second inner link plate 120. The roller 170 has a roller hole 171 through which the annular axial protrusions 111B, 112B, 121B, and 122B are inserted. The roller 170 can rotate relative to the annular axial protrusions 111B, 112B, 121B, and 122B. When the bicycle chain 100 is installed on the bicycle A, the roller 170 contacts the sprocket teeth.

In the bicycle chain 100 of this embodiment, at least the portions of the outer peripheral surfaces 151 and 161 of pins 150 and 160 that slide against the inner link sliding surfaces 111C, 121C, 112C, and 122C of the inner link plates 110 and 120, respectively, are formed with a pin-hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride. By using these materials to form a hardened layer on the surface of the pin, the surface hardness can be increased compared to simply using heat treatment or other methods to harden the pin material, thereby reducing wear. On the other hand, the wear of the sliding object will increase. Therefore, it is ideal to have a fixed range of surface hardness.

Bicycle chains engage multiple sprockets arranged side-by-side in the width direction during gear shifting, causing alignment misalignment and resulting in a bent configuration in the width direction. Therefore, a predetermined gap is maintained between the sliding surface of the inner link and the outer circumference of the pin. Sliding is not always under fixed conditions; the sliding part constantly changes, and the pressing force on the sliding part is not constant, frequently experiencing impactful increases. At this point, the sliding part of the inner link (bent into a concave shape) is less elastically deformable than the sliding part of the pin (bent into a convex shape), and therefore less able to absorb pressure or impact. Consequently, with the same surface hardness, the outer circumference of the pin experiences greater wear or damage than the sliding surface of the inner link. Therefore, a pin-hardening layer with a higher surface hardness than the sliding surface of the inner link is applied to the outer circumference of the pin. This improves the pin's wear resistance, suppresses chain elongation, and increases drive efficiency. Furthermore, if a link-hardening layer is also applied to the sliding surface of the inner link, its wear resistance is further improved, and chain elongation is suppressed.

100: Bicycle chain 101: Transmission system 102: Bicycle crank assembly 103: Front sprocket 104: Rear sprocket 105: Crankshaft 106: Crank arm 110: First inner link plate 111: First inner link end 111A: First inner link opening 111B: First annular axial protrusion 111BN: First proximal end 111BF: First distal end 111C: First inner link sliding surface 111D: First inner link opening recess 111E: First inner link sprocket tooth holding portion 112: Second inner link end 112A: Second inner link opening 112B: Second annular axial protrusion 112BN: Second proximal end 112BF: Second distal end 112C: Second inner link sliding surface 112D: Second inner link opening recess 112E: Second inner link sprocket tooth holding portion 113: First inner link middle portion 114: First inner link surface 115: Second inner link surface 116: First inner link Link Recess 117: First Inner Link Chamfer 118: Second Inner Link Chamfer 120: Second Inner Link Plate 121: Third Inner Link End 121A: Third Inner Link Opening 121B: Third Circular Axial Protrusion 121BN: Third Proximal End 121BF: Third Distal End 121C: Third Inner Link Sliding Surface 121D: Third Inner Link Opening Recess 121E: Third Inner Link Sprocket Tooth Retention Part 122: Fourth Inner Link End 122A: The... Fourth inner link opening 122B: Fourth annular axial protrusion 122BN: Fourth proximal end 122BF: Fourth distal end 122C: Fourth inner link sliding surface 122E: Fourth inner link sprocket tooth holding part 123: Second inner link middle part 124: Third inner link surface 125: Fourth inner link surface 126: Second inner link recess 127: Third inner link chamfer 128: Fourth inner link chamfer 130: First outer link plate 131: First outer link End Points 131A: First Outer Link Opening 132: Second Outer Link End 132A: Second Outer Link Opening 133: Middle Part of First Outer Link 134: First Outer Link Face 135: Second Outer Link Face 140: Second Outer Link Plate 141: Third Outer Link End 141A: Third Outer Link Opening 142: Fourth Outer Link End 142A: Fourth Outer Link Opening 143: Middle Part of Second Outer Link 144: Third Outer Link Face 145: Fourth Outer Link Surface 150: First pin 151: First outer peripheral surface 152: First pin through hole 153: First pin axial end face 154: Second pin axial end face 155: First shaft body 156: First locking part 157: Second locking part 160: Second pin 161: Second outer peripheral surface 162: Second pin through hole 163: Third pin axial end face 164: Fourth pin axial end face 165: Second shaft body 170: Roller 171: Roller hole A1: First inner Link center axis A2: Second inner link center axis A3: Third inner link center axis A4: Fourth inner link center axis B1: First outer link center axis B2: Second outer link center axis B3: Third outer link center axis B4: Fourth outer link center axis P1: First pin center axis P2: Second pin center axis DA: First inner link axis direction DB: Second inner link axis direction DC: Third inner link axis direction DD: Fourth inner link axis direction DE: First outer link axial direction DF: Second outer link axial direction DP: First pin direction DP2: Second pin direction LL1: Length of sliding surface in the first axial direction LL2: Length of sliding surface in the second axial direction LL3: Length of sliding surface in the third axial direction LL4: Length of sliding surface in the fourth axial direction LP1: Length in the first pin direction LP2: Length in the second pin direction WL1: First radial thickness WL2: Second radial thickness WL3: Third radial thickness WL4: Fourth radial thickness

Figure 1 is a schematic diagram of a bicycle viewed from above. Figure 2 is a perspective view of a bicycle chain according to the first embodiment. Figure 3 is an exploded view of the bicycle chain according to the first embodiment. Figure 4 is an enlarged view of the first (second) inner link plate of Figure 3. Figure 5 is an enlarged view of the first (second) outer link plate of Figure 3. Figure 6 is an enlarged view of the first (second) pin of Figure 3. Figure 7 is a cross-sectional view of the bicycle chain of the first embodiment before riveting along its long side. Figure 8 is a partial enlarged view of Figure 7 after riveting. Figure 9 is a dimensional diagram illustrating the sliding surface between the first pin and the first (second) inner link plate. Figure 10 is a dimensional diagram illustrating the sliding surface between the second pin and the first (second) inner link plate.

100: Bicycle chains

101: Transmission System

102: Bicycle crank assembly

103:Front sprocket

104:Rear sprocket

105: Crankshaft

106: Crank arm

Claims (26)

A bicycle chain comprising multiple inner link plates, multiple outer link plates, and multiple pins, characterized in that the multiple pins, located on a portion or all of their outer peripheral surfaces, have a pin-hardened layer comprising any one of Ti carbide, Nb carbide, Cr nitride, and Ti nitride, wherein the multiple pins include connecting pins for linking the chain into an endless shape, and the surface wear resistance of the connecting pins is lower than that of the other pins. The bicycle chain as described in claim 1, wherein the pin-hardened layer has a sliding surface hardness of 1000 HV or higher and 3500 HV or lower. The bicycle chain as claimed in claim 1, wherein the plurality of inner link plates have inner link sliding surfaces that slide against the outer peripheral surface of the pin, and the hardness of the sliding surface of the pin hardened layer is greater than the surface hardness of the inner link sliding surface. The bicycle chain as claimed in claim 1, wherein the plurality of inner link plates have an inner link sliding surface that slides with the outer peripheral surface of the pin, and wherein a portion or all of the inner link sliding surface has a link hardened layer comprising any one of Cr carbide, Ti carbide, V carbide, Nb carbide, Cr nitride, Ti nitride, V nitride, and Nb nitride. The bicycle chain as claimed in claim 1, wherein the plurality of inner link plates have inner link sliding surfaces that slide with the outer peripheral surface of the pin, and the surface roughness of the hardened layer of the pin is smaller than the surface roughness of the inner link sliding surfaces. The bicycle chain as described in claim 1, wherein the plurality of inner link plates includes a first inner link plate and a second inner link plate, the plurality of outer link plates includes a first outer link plate and a second outer link plate, the plurality of pins includes a first pin, and the first inner link plate includes: a first inner link end, including a first inner link opening having a central axis of the first inner link, and a first annular axial protrusion surrounding the first inner link opening in a circumferential direction with the central axis of the first inner link as the axis; and a second inner link end, including a second inner link extending parallel to the central axis of the first inner link. The system comprises: a second inner link opening centered on a central axis; a second annular axial protrusion surrounding the second inner link opening in a circumferential direction with the central axis of the second inner link as its axis; a middle portion of a first inner link connecting the ends of the first and second inner links; a first inner link surface; and a second inner link surface disposed on the opposite side of the first inner link surface in the axial direction passing through the central axis of the first inner link; the first annular axial protrusion having a first proximal end and a first distal end connected to the first inner link surface; and the second annular axial protrusion... The second inner link plate has a second proximal end and a second distal end connected to the first inner link surface. The second inner link plate includes: a third inner link end portion, comprising a third inner link opening having a central axis of the third inner link, and a third annular axial protrusion surrounding the third inner link opening in a circumferential direction with the central axis of the third inner link as its axis; and a fourth inner link end portion, comprising a fourth inner link opening having a central axis of the fourth inner link extending parallel to the central axis of the third inner link, and a third inner link opening surrounding the fourth inner link opening in a circumferential direction with the central axis of the fourth inner link as its axis. The bicycle chain has four annular axial protrusions; a second inner link middle portion connecting the end of the third inner link and the end of the fourth inner link; a third inner link face, configured such that, in the assembled state of the bicycle chain, it faces the first inner link face of the first inner link plate in the axial direction of the first inner link; and a fourth inner link face, disposed on the opposite side of the third inner link face in the axial direction of the second inner link, passing through the central axis of the third inner link; each annular axial protrusion has a third proximal end and a third distal end connected to the third inner link face. The first outer link plate is configured to face the first distal end of the first annular axial protrusion in the assembled state of the bicycle chain. The fourth annular axial protrusion has a fourth proximal end and a fourth distal end connected to the third inner link surface. The fourth distal end is configured to face the second distal end of the second annular axial protrusion in the assembled state of the bicycle chain. The first outer link plate is configured to be adjacent to the first inner link plate without passing through other inner link plates or other outer link plates in the assembled state of the bicycle chain. The first outer link plate includes: a first outer link end portion including a first outer link opening having a central axis of the first outer link; a second outer link end portion including a second outer link opening having a central axis of the second outer link extending parallel to the central axis of the first outer link; a middle portion of the first outer link connecting the first outer link end portion and the second outer link end portion; a first outer link face; and a second outer link face, disposed on the opposite side of the first outer link face in the direction of the first outer link axial direction passing through the central axis of the first outer link; the second outer link plate is for the bicycle chain. In its assembled state, the second outer link plate is configured to be adjacent to the second inner link plate without being connected by other inner link plates or other outer link plates. The second outer link plate includes: a third outer link end, comprising a third outer link opening having a third outer link central axis; a fourth outer link end, comprising a fourth outer link opening having a fourth outer link central axis extending parallel to the central axis of the third outer link; a second outer link middle portion, connecting the third outer link end and the fourth outer link end; and a third outer link face, so that in the assembled state of the bicycle chain, in the axial direction of the first outer link... The chain has a first outer link face facing the first outer link plate; and a fourth outer link face, disposed on the opposite side of the third outer link face in the direction of the second outer link axis passing through the central axis of the third outer link; the first pin is configured to be inserted into the openings of the first outer link, the third outer link, the first inner link, and the third inner link in the assembled state of the bicycle chain, and has a first outer peripheral surface that slides against the first annular axial protrusion and the third annular axial protrusion in the use state of the bicycle chain. The bicycle chain as described in claim 6, wherein the plurality of pins includes a second pin, the second pin being configured, in the assembled state of the bicycle chain, to pass through the openings of the second outer link, the fourth outer link, the second inner link, and the fourth inner link, and having a second outer peripheral surface that slides with the second and fourth annular axial protrusions in the use state of the bicycle chain. The bicycle chain as described in claim 6, wherein the first proximal end of the first axially oriented circumferential protrusion is integrally connected to the first inner link face by a single material, and the second proximal end of the second axially oriented circumferential protrusion is integrally connected to the first inner link face by a single material. The bicycle chain as described in claim 6, wherein the plurality of inner link plates have inner link sliding surfaces that slide against the outer peripheral surface of the pin, wherein the inner link sliding surfaces include a first inner link sliding surface and a second inner link sliding surface, the first inner link plate having the first inner link sliding surface, the first inner link sliding surface being formed on the inner peripheral surface of the opening of the first inner link and the inner surface of the first annular axial protrusion. The second inner link plate extends parallel to the central axis of the first inner link and slides against the first outer peripheral surface of the first pin. The second inner link sliding surface is formed on the inner peripheral surface of the opening of the third inner link and the inner peripheral surface of the third annular axial protrusion, extends parallel to the central axis of the third inner link, and slides against the first outer peripheral surface of the first pin. The bicycle chain as described in claim 9, wherein the sliding surface of the first inner link has a first axial sliding surface length of 0.5 mm or more and 3.5 mm or less in the axial direction of the first inner link, and the sliding surface of the second inner link has a second axial sliding surface length of 0.5 mm or more and 3.5 mm or less in the axial direction of the second inner link. The bicycle chain as described in claim 9, wherein the first inner link sliding surface has a first inner link sliding surface hardness of 200 HV or higher and 2500 HV or lower, and the second inner link sliding surface has a second inner link sliding surface hardness of 200 HV or higher and 2500 HV or lower. As described in claim 9, in a bicycle chain, wherein the first inner link sliding surface has a first axial sliding surface length defined in the axial direction of the first inner link, the second inner link sliding surface has a second axial sliding surface length defined in the axial direction of the second inner link, and the first pin, in the assembled state of the bicycle chain, has a first pin center axis, a first pin axial end face, a second pin axial end face, and a first shaft body, the first shaft body being... In the first pin axis direction, extending between the first pin axis end face and the second pin axis end face, the length in the first pin axis direction is defined by the distance between the first pin axis end face and the second pin axis end face. The ratio of the first pin axis length to the length of the sliding surface in the first axis direction is 2 or more and 7 or less, and the ratio of the first pin axis length to the length of the sliding surface in the second axis direction is also 2 or more and 7 or less. The bicycle chain as described in claim 12, wherein the ratio of the length in the first pin direction to the length of the sliding surface in the first axial direction is 3.5 or more and 6 or less, and the ratio of the length in the first pin direction to the length of the sliding surface in the second axial direction is 3.5 or more and 6 or less. As described in claim 6, in a bicycle chain, wherein the first annular axial protrusion has a first radial thickness defined in the radial direction about the central axis of the first inner link, and the third annular axial protrusion has a second radial thickness defined in the radial direction about the central axis of the third inner link, and the first pin, in the assembled state of the bicycle chain, has a first pin central axis, a first pin axial end face, a second pin axial end face, and a first shaft body. The first shaft extends along a first pin axis passing through the center of the first pin, between its first pin axis end face and its second pin axis end face. The length along the first pin axis is defined by the distance between the first pin axis end face and the second pin axis end face. The ratio of the first pin axis length to the first radial thickness is 6 or more and 20 or less, and the ratio of the first pin axis length to the second radial thickness is also 6 or more and 20 or less. The bicycle chain as described in claim 14, wherein the ratio of the length in the first pin direction to the first radial thickness is 8 or more and 15 or less, and the ratio of the length in the first pin direction to the second radial thickness is 8 or more and 15 or less. As described in claim 6, in the assembled state of the bicycle chain, the first pin has a first pin center axis, a first pin axis end face, a second pin axis end face, and a first shaft body, wherein the first shaft body extends in the first pin axis direction through the first pin center axis between the first pin axis end face and the second pin axis end face. The bicycle chain as described in claim 16, wherein a first locking portion is formed around the entire circumference of the end face in the first pin direction, and a second locking portion is formed around the entire circumference of the end face in the second pin direction in the first pin direction. The bicycle chain as claimed in claim 17, wherein the first locking portion is formed around the entire circumference of the end face in the direction of the first pin by a riveting step, and the second locking portion is formed around the entire circumference of the end face in the direction of the second pin by a riveting step. The bicycle chain as described in claim 16, wherein the first pin-direction end face is located on the same plane as the second outer link face, or between the first and second outer link faces in the first pin direction passing through the first pin center axis; the second pin-direction end face is located on the same plane as the fourth outer link face, or between the third and fourth outer link faces in the first pin direction passing through the first pin center axis. The bicycle chain as described in claim 6, wherein the first pin, in the assembled state of the bicycle chain, is inserted in a pressed-in state into the openings of the first and third outer links. The bicycle chain as claimed in claim 6, wherein the first inner link plate has a first inner link recess formed from the first inner link surface toward the second inner link surface, at least in the middle portion of the first inner link, and the second inner link plate has a second inner link recess formed from the third inner link surface toward the fourth inner link surface, at least in the middle portion of the second inner link. The bicycle chain as claimed in claim 6, wherein the second inner link surface at the middle portion of the first inner link is flat, and the fourth inner link surface at the middle portion of the second inner link is flat. The bicycle chain as described in claim 6, wherein a first inner link opening recess is formed around the first inner link opening in the second inner link face, a second inner link opening recess is formed around the second inner link opening in the second inner link face, a third inner link opening recess is formed around the third inner link opening in the fourth inner link face, and a fourth inner link opening recess is formed around the fourth inner link opening in the fourth inner link face. The bicycle chain as described in claim 6, wherein the first inner link end of the first inner link plate has a first inner link sprocket tooth retaining portion, the first inner link sprocket tooth retaining portion being configured to retain the sprocket tooth when the bicycle chain is engaged with the sprocket tooth of the bicycle sprocket, and the second inner link end of the first inner link plate has a second inner link chain. The second inner link sprocket tooth retaining portion is configured to retain the sprocket teeth when the bicycle chain engages with the sprocket teeth of the bicycle sprocket. A first inner link chamfer is formed on the first inner link surface of the first inner link sprocket tooth retaining portion, and a second inner link chamfer is formed on the first inner link surface of the second inner link sprocket tooth retaining portion. The bicycle chain as described in claim 6, wherein the third inner link end of the second inner link plate has a third inner link sprocket tooth retaining portion, the third inner link sprocket tooth retaining portion being configured to retain the sprocket tooth when the bicycle chain is engaged with the sprocket tooth of the bicycle sprocket, and the fourth inner link end of the second inner link plate has a fourth inner link. The sprocket tooth retaining portion, the fourth inner link sprocket tooth retaining portion, is configured to retain the sprocket teeth when the bicycle chain is engaged with the sprocket teeth of the bicycle sprocket. A third inner link chamfer is formed on the third inner link surface of the third inner link sprocket tooth retaining portion, and a fourth inner link chamfer is formed on the third inner link surface of the fourth inner link sprocket tooth retaining portion. A bicycle chain as described in any of claims 1 to 25, wherein the plurality of pins includes those having pin through holes extending along their long sides.