Bicycle crank arrangement

Abstract

Bicycle crank assembly (10), comprising: a sprocket (18) with a central axis of rotation (A1); a crank shaft (14) extending along the rotational center axis (A1), the crank shaft (14) having an inner space (14S); a movable member (26) movably provided in the inner space (14S), which is further connected to the sprocket to move with the sprocket 18 with respect to the crank axis 14 in the axial direction (D2) of the rotational center axis (A1); a torque transmission element (42) for transmitting a pedal actuation torque from the crank axle (14) to the sprocket (18); and a bearing structure (56) arranged between the movable member (26) and the crank axis (14) to slidably support the movable member (26) in the axial direction (D2), wherein the bearing structure (56) is arranged at a location different from a location of the torque transmission member (42) in the axial direction (D2).

Description

BACKGROUND OF THE INVENTIONREFERENCE TO FURTHER APPLICATIONSThis application claims priority to U.S. patent application US 15 / 621,994, filed June 13, 2017. The entire disclosure of U.S. patent application Ser. No. 15 / 621,994 is hereby incorporated by reference.FIELD OF THE INVENTIONThe present invention relates to a bicycle crank assembly.BACKGROUND DISCUSSIONBiking is becoming an increasingly more popular form of recovery as well as transportation. Moreover, biking has become a very popular competitive sport for amateurs and professionals. Whether the bicycle is used for recreational, shipping or competition, the bicycle industry constantly improves the various components of the bicycle. A bicycle component that has been comprehensively reconfigured is a crank assembly. For example, DE 10 2015 104 670 A1 shows a bicycle crank arrangement which has a rotational central axis and is basically provided with a crank element and a sprocket element. The crank member includes a bearing portion extending in the axial direction and an arm portion integrally rotatable with the bearing portion about the rotational center axis. The ring gear member includes a sliding portion which extends in the axial direction, which is integrally rotatable with respect to the bearing portion, and which is slidable in the axial direction. The bicycle crank assembly is designed to achieve high strength and suppress the decrease in efficiency of rotation transmission from the crank member to the sprocket member in a crank assembly in which the sprocket member is movable in the axial direction. FR 2 881 199 A1 shows a transmission with a crankset which has a toothed chain plate which is displaced laterally parallel to a rotational axis of the crankset. The chainring is slid by an actuator integrated with a vertical tube of a bicycle. The actuator is comprised of a main body and a roller rotatably mounted on a shaft translationally guided in the body. The chainring engages in a recess of the roller. US 2013 / 0 008 282 A1 discloses a bicycle transmission system that includes a sprocket or ring that is slidable between an infinite number of lateral positions relative to a crank arm. WO 2016 / 033 623 A1 shows a regulating device for a transmission ratio between a traction means and a wheel set which can be rotated about a wheel axis and has at least two wheel profiles which are optionally wrapped around by the traction means, wherein at least one of the wheel profiles is composed of a plurality of rim segments which can be adjusted independently of one another. DE 10 2016 014 681 A1 discloses a bicycle crank arrangement that includes a sprocket having a rotational center axis, a crank, a crankshaft and a sliding mechanism.SUMMARY OF THE INVENTIONModern bicycle transmission systems often use a single front sprocket on the crankset and multiple sprockets on the cassette. These systems typically employ at least one derailleur to shift the chain from sprocket to sprocket on the rear cassette. In shifting the bicycle transmission, the chain angularly connects the sprocket to the rear cassette unless the center sprockets are used. The inclined position of the chain between the bicycle crank assembly and the rear cassette presents two problems. First, when the chain is angled, the chain joints are no longer correctly aligned with one another and are therefore constantly bent. This leads to unnecessary friction in the individual chain joints. Second, the chain reaches both the front and rear sprockets at an angle. Both lead to unnecessary friction of the entire bicycle transmission system. Therefore, this additional friction reduces the efficiency of the transmission of power from the driver to the wheels.Therefore, it is an object of the present disclosure to provide a bicycle transmission system that overcomes the above-mentioned deficiencies. In particular, a bicycle crank arrangement is proposed here which provides a smooth and more accurate chain path for bicycle transmission systems and reduces the angle of inclination of the bicycle chain.A bicycle crank assembly according to the first embodiment of the present invention includes a sprocket, a crank axle, a movable member, a torque transmitting member, and a bearing structure. The sprocket has a rotational center axis. The crankshaft extends along the rotational central axis. The crank axle includes an interior space. The movable member is movably provided in the internal space. Further, the movable member is connected to the sprocket to move with the sprocket 18 with respect to the crank axis 14 in the axial direction D 2 of the rotational center axis (A 1). The torque transmitting member is to transmit a pedal actuation torque from the crank axle to the sprocket. The bearing structure is disposed between the movable member and the crank shaft to support the movable member slidably in the axial direction. The bearing structure is disposed at a location different from a location of the torque transmitting member in the axial direction.With the bicycle crank assembly according to the first aspect, it is possible to transmit the pedaling torque from the crank axle to the sprocket with the torque transmitting member disposed at a position other than the position of the bearing structure. This simplifies the structure of the bicycle crank assembly.In accordance with another aspect of the present invention, the bicycle crank assembly includes a crank arm attached to the crank axle. The torque transmitting member is connected to one of the crank axles to be fixed with respect to the crank axle in the axial direction, or the torque transmitting member is connected to the movable member to be movable with respect to the movable member in the axial direction.With the bicycle crank assembly according to the further aspect, it is possible to transmit the pedal torque from the crank axle to the sprocket, wherein the torque transmitting member is disposed at a position different from the position of the bearing structure. This simplifies a structure of the bicycle crank assembly.In accordance with another aspect of the present invention, the bicycle crank assembly according to the first or second aspect is configured so that the torque transmitting member is fixed relative to the crank axis and movable relative to the movable member in the axial direction.With the bicycle crank assembly according to the further aspect, the torque transmitting member can be easily fixed to the crank axle.In accordance with another aspect of the present invention, the bicycle crank assembly according to the third aspect is configured so that the movable member has a groove extending in the axial direction. The torque transmitting member is provided in the groove to be slidable along the groove.In the bicycle crank assembly according to the further aspect, the groove allows the torque transmitting member to move relative to the movable member in the axial direction.In accordance with another aspect of the present invention, the bicycle crank assembly according to the fourth aspect is configured so that the torque transmitting member has a first surface and a second surface. The first surface is directed in the circumferential direction of the rotational center axis. The second surface is circumferentially directed. The second surface is provided on a rear side of the first surface in the circumferential direction.In the bicycle crank assembly according to the further aspect, at least one of the first and second surfaces effectively transmits the pedaling torque to the sprocket.In accordance with another aspect of the present invention, the bicycle crank assembly according to the another aspect is configured so that the movable member has a first receiving surface and a second receiving surface. The first receiving surface is circumferentially directed. The first receiving surface may be contacted with the first surface. The second receiving surface faces the first receiving surface in the circumferential direction. The second receiving surface may be contacted with the second surface. The first receiving surface and the second receiving surface at least partially form the groove.In the bicycle crank assembly according to the further aspect, at least one of the first and second receiving surfaces effectively transmits the pedaling torque to the sprocket.In accordance with another aspect of the present invention, the bicycle crank assembly according to the another aspect is configured so that at least one of the first surface and the second surface is inclined with respect to a reference plane parallel to the axial direction, the reference plane extending radially outward from the rotational center axis.In the bicycle crank assembly according to the further aspect, the inclination of the at least one of the first and second surfaces enables a clearance between the torque transmitting member and a surface of the groove to be changed.In accordance with another aspect of the present invention, the bicycle crank assembly according to any of the other aspects is configured such that the torque transmitting member has a radially outer surface and a radially inner surface. The radially outer surface is directed radially outward. The radially inner surface is directed radially inward. The radially inner surface is radially provided on a rear side of the radially outer surface. The first surface and the second surface are inclined relative to each other to increase a circumferential width of the torque transmitting member from the radially inner surface to the radially outer surface.In the bicycle crank assembly according to the further aspect, the inclination of the at least one of the first and second surfaces enables the variation of the clearance between the torque transmitting member and the surface of the groove.In accordance with another aspect of the present invention, the bicycle crank assembly according to any one of the other aspects further comprises an adjustment structure configured to change a radial position of the torque transmitting member with respect to the groove.In the bicycle crank assembly according to the further aspect, the adjustment structure enables a range of a contact surface between the torque transmitting member and a surface of the groove to be varied. In a case where the contact surface of the torque transmitting member and / or the groove is inclined, the inclination of the contact surface enables a variation of a clearance between the torque transmitting member and a surface of the groove.In accordance with another aspect of the present invention, the bicycle crank assembly according to the ninth aspect is configured so that the adjustment structure is accessible from an outer side of the crank axle.With the bicycle crank assembly according to the further aspect, it is possible to change the radial position of the torque transmission member without disassembling the bicycle crank assembly.In accordance with another aspect of the present invention, the bicycle crank assembly according to any one of the other aspects further comprises a sliding structure provided between the torque transmitting member and the groove.In the bicycle crank assembly according to the further aspect, the sliding structure reduces friction between the torque transmitting member and the groove.In accordance with another aspect of the present invention, the bicycle crank assembly according to the another aspect further comprises a biasing member for biasing the slide structure toward the groove.In the bicycle crank assembly according to the further aspect, the biasing member stabilizes a position of the slide structure with respect to the groove.In accordance with another aspect of the present invention, the bicycle crank assembly according to the another aspect is configured so that the biasing member is disposed in the torque transmitting member.With the bicycle crank assembly according to the other aspect, it is possible to use an inner space of the torque transmission member as a space for the biasing member.In accordance with another aspect of the present invention, the bicycle crank assembly according to any one of the other aspects is configured such that a gap is provided between the torque transmitting member and the movable member in the radial direction of the rotational center axis.In the bicycle crank assembly according to the further aspect, the gap reduces an air resistance generated when the movable member moves in the axial direction with respect to the crank axis.In accordance with another aspect of the present invention, the bicycle crank assembly according to any one of the other aspects is configured such that the crank axis has a first axis end and a second axis end, the crank axis extending along the rotational center axis between the first axis end and the second axis end. The bearing structure is provided between the first axle end and the torque transmitting member.With the bicycle crank assembly according to the another aspect, it is possible to use a space for the torque transmission member disposed around an axial center of the inner space.In accordance with another aspect of the present invention, the bicycle crank assembly according to any one of the described aspects is configured such that the movable member is movable with respect to the crank axis in the axial direction in a movable range, and the bearing structure is movable with respect to the crank axis in the axial direction in a movable range of bearings. The bearing movement range is smaller than the movement range of the movable member.With the bicycle crank assembly according to the other aspect, it is possible to make the bearing structure compact in the axial direction.In accordance with another aspect of the present invention, the bicycle crank assembly according to any one of the described aspects is configured so that the bearing movable range is equal to or greater than 50% of the movable range of the movable member.With the bicycle crank assembly according to the further aspect, it is possible to minimize an axial length of the bearing structure.In accordance with another aspect of the present invention, the bicycle crank assembly according to any of the described aspects further comprises a bushing member circumferentially disposed with the torque transmitting member.In the bicycle crank assembly according to the further aspect, the bushing member stably moves the movable member in the axial direction with respect to the crank axis.In accordance with another aspect of the present invention, the bicycle crank assembly according to the another aspect is configured so that the bushing member has a slit extending in the axial direction. The torque transmitting member is provided in the slot.With the bicycle crank assembly according to the other aspect, it is possible to effectively locate the torque transmitting member and the bushing member in the interior space.According to another aspect of the present invention, the sprocket unit has a reference surface perpendicular to the rotational center axis. The reference surface is an axially outermost surface of the sprocket unit. The crank arm has a pedal attachment end with an axially outermost surface. The movable member is provided movably with respect to the crank axis to move the sprocket unit from an axially outward position to an axially inward position in an axial direction of the rotational center axis. The reference surface is provided in an axial position that is equal to an axial position of the axially outwardmost surface in a state where the sprocket unit is in the axially outward position, or is disposed axially inward from the axially outermost surface in the axial direction in the state where the sprocket unit is in the axially outward position.With the bicycle crank assembly according to the further aspect, it is possible to reduce or prevent interference between the sprocket unit and a leg of a rider even when the sprocket unit moves to the axially outward position.BRIEF DESCRIPTION OF THE DRAWINGSA more comprehensive assessment of the invention and many of the attendant advantages will be readily obtained as the same becomes better understood in connection with the accompanying drawings from the following detailed description. FIG. 1 is a perspective view of a bicycle crank assembly according to an embodiment. FIG. 2 is another perspective view of a bicycle crank assembly illustrated in FIG. 1. FIG. 3 is a cross-sectional view of the bicycle crank assembly taken along line III-III of FIG. 1. FIG. 4 is a partial exploded perspective view of the bicycle crank assembly illustrated in FIG. 1. FIG. 5 is another partial exploded perspective view of the bicycle crank assembly illustrated in FIG. 1. FIG. 6 is a side elevational view of the bicycle crank assembly illustrated in FIG. 1. FIG. 7 is a cross-sectional view of the sprocket of the bicycle crank assembly taken along line VII-VII of FIG. 6. FIG. 8 is a cross-sectional view of the sprocket of the bicycle crank assembly taken along line VIII-VIII of FIG. 6. FIG. 9 is a partially enlarged cross-sectional view of the bicycle crank assembly illustrated in FIG. 3. FIG. 10 is a partial exploded perspective view of the bicycle crank assembly illustrated in FIG. 1. FIG. 11 is a cross-sectional view of the sprocket of the bicycle crank assembly taken along line XI-XI of FIG. 9. FIG. 12 is a partially enlarged cross-sectional view of the sprocket of the bicycle crank assembly illustrated in FIG. 11. FIG. 13 is a cross-sectional view of the sprocket of the bicycle crank assembly taken along line XIII-XIII of FIG. 1. FIG. 14 is a cross-sectional view of the sprocket of the bicycle crank assembly taken along line XIV-XIV of FIG. 9. FIG. 15 is a partial exploded perspective view of the bicycle crank assembly illustrated in FIG. 1. FIG. 16 is a top view of the bicycle crank assembly illustrated in FIG. 1.DESCRIPTION OF THE EMBODIMENTSThe embodiment(s) will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings.Referring first to FIG. 1, a bicycle crank assembly 10 according to an embodiment includes a sprocket unit 12, a crank axle 14, and a crank arm 16. Namely, the bicycle crank 10 has the sprocket 18. The sprocket 18 has a rotational center axis A 1. The sprocket 18 is engaged with a bicycle chain C. In this embodiment, the sprocket 18 is a single sprocket in the sprocket unit 12, but the sprocket unit 12 may include multiple sprockets.The crank axis 14 extends along the rotational center axis A 1. The crank arm 16 is fixed to the crank axle 14. The bicycle crank assembly 10 includes an additional crank arm 20. The crank arm 16 has a pedal attachment end 22. The pedal attachment end 22 has a pedal attachment hole 22A. A bicycle pedal (not shown) is fixed to the pedal attachment end 22 (more specifically, to the pedal attachment hole 22A). The additional crank arm 20 includes an additional pedal attachment end 24. the additional pedal attachment end 24 includes an additional pedal attachment hole 24A. An additional bicycle pedal (not shown) is attached to the additional pedal attachment end 24 (more specifically, the additional pedal attachment hole 24A).The bicycle crank assembly 10 is rotatable relative to a bicycle frame (not shown) about the rotational center axis A 1 in the driving rotational direction D 11 during pedaling. The driving rotational direction D 11 is defined along a circumferential direction D 1 of the bicycle crank assembly 10. A reverse rotation direction D 12 is opposite to the drive rotation direction D 11 and is defined along the circumferential direction D 1. A pedaling torque T 1 is transmitted to the sprocket unit 12 via the crank axle 14 during pedaling of at least one of the crank arm 16 and the additional crank arm 20.As seen in FIG. 2, the crank axle 14 includes a first axle end 14A and a second axle end 14B. The crank axis 14 extends between the first axis end 14A and the second axis end 14B along the rotational center axis A 1. The crank arm 16 is attached to the first axle end 14A. The additional crank arm 20 is attached to the second axle end 14B. In this embodiment, the crank arm 16 is a right crank arm and the additional crank arm 20 is a left crank arm. The first axle end 14A is a right end of the crank axle 14. the second axle end 14B is a left end of the crank axle 14. however, the crank arm 16 may be a left crank arm and the additional crank arm 20 may be a right crank arm.In the present application, the following directional terms "front", "rear", "front", "rear", "left", "right", "transverse", "upward", and "downward", as well as any other similar directional terms refer to those directions determined based on a user (e.g., a rider) who sits on a saddle (not shown) of a bicycle with respect to a handlebar (not shown). Accordingly, these terms, as used to describe the bicycle crank assembly 10, are to be interpreted relative to the bicycle equipped with the bicycle crank assembly 10 as used in an upright position on a horizontal surface.As seen in FIG. 3, the crank axle 14 has an inner space 14S. The interior space 14S extends between the first axis end 14A and the second axis end 14B along the rotational center axis A 1. The first axle end 14A includes a first end opening 14A 1. The second axle end 14B includes a second end opening 14B 1. The interior space 14S extends between the first end opening 14A 1 and the second end opening 14B 1 to connect the first end opening 14A 1 to the second end opening 14B 1.The crank axle 14 includes an intermediate part 14C. The intermediate part 14C is provided between the first axis end 14A and the second axis end 14B. The first axis end 14A has a first outer diameter DM 1. The second axis end 14B has a second outer diameter DM 2. The intermediate element has a third outer diameter DM 3. The third outer diameter DM 3 is smaller than the first outer diameter DM 1 and the second outer diameter DM 2. However, the third outer diameter DM 3 may be equal to or greater than at least one of the first outer diameter DM 1 and the second outer diameter DM 2.The bicycle crank assembly 10 includes a movable member 26. the movable member 26 is movably provided in the inner space 14S to move the sprocket 18 in an axial direction D 2 of the rotational center axis A 1. The movable member is connected to the sprocket 18 to move with the sprocket 18 with respect to the crank axis 14 in the axial direction D 2. The movable member 26 extends through the first end opening 14A 1 of the first axis end 14A.As seen in FIG. 4, the sprocket unit 12 includes a fastening member 28. The fastener 28 includes a fastener body 30, a first fastener arm 32A, a second fastener arm 32B, a third fastener arm 32C, and a fourth fastener arm 32D. The first to fourth mounting arms 32A to 32D extend radially outward from the mounting body 30. The first to fourth mounting arms 32A to 32D are spaced apart from each other in the circumferential direction D 1.The movable member 26 includes a first end 26A, a second end 26B, and an outer spline 26S. The movable member 26 extends between the first end 26A and the second end 26B. The external spline 26S is provided at the first end 26A. The mounting body 30 includes an internal spline 30A. The external spline 26S meshes with the internal spline 30A to integrally rotate the movable member 26 with the sprocket unit 12. The sprocket 12 includes a first limiting member 29A and a second limiting member 29B. The first and second limiting members 29A and 29B are fixed to the fixing member 28 to limit relative movement between the sprocket unit 12 and the movable member 26 in the axial direction D 2.The sprocket 18 includes a sprocket ring 34, a plurality of sprocket teeth 36, a first link 40A, a second link 40B, a third link 40C, and a fourth link 40D. The plurality of sprocket teeth 36 extend radially outward from the sprocket ring 34. The first to fourth link members 40A to 40D extend radially inward from the sprocket ring 34. The first to fourth connecting members 40A to 40D are spaced apart from each other in the circumferential direction D 1. The first link 40A is fixed to the first fixing arm 32A. The second link 40B is fixed to the second fixing arm 32B. The third link 40C is fixed to the third fixing arm 32C. The fourth link 40D is fixed to the fourth fixing arm 32D.In this embodiment, the sprocket assembly 12 includes a sprocket attachment 38 such as a screw or rivet. The sprocket ring 34 is fastened to the fastener 28 with the sprocket fastener 38. The first link 40A is attached to the first attachment arm 32A with the sprocket attachment 38. The first connecting member 40A includes a circumferential stop 40A 1 and a connecting threaded bore 40A 2. The first mounting arm 32A includes a through hole 32A 1. The sprocket attachment 38 includes an externally threaded portion 38A. The sprocket attachment 38 extends through the through hole 32A 1 of the first attachment arm 32A. The male threaded portion 38A is threadedly engaged with the connecting thread 40A 2.As seen in FIGS. 4 and 5, the second mounting arm 32B includes a mounting groove 32B 1 extending in the circumferential direction D 1. The third mounting arm 32C includes a mounting groove 32C 1 extending in the circumferential direction D 1. The fourth mounting arm 32D includes a mounting groove 32D 1 extending in the circumferential direction D 1. The second connection part 40B includes a circumferential stopper 40B 1 and a guide 40B 2 extending from the circumferential stopper 40B 1 in the circumferential direction. The third connection part 40C includes a circumferential stopper 40C 1 and a guide 40C 2 extending from the circumferential stopper 40C 1 in the circumferential direction. The fourth connection part 40D includes a circumferential stopper 40D 1 and a guide 40D 2 extending from the circumferential stopper 40D 1 in the circumferential direction.As seen in FIG. 6, the circumferential stopper 40A 1 is in contact with the first mounting arm 32A in the circumferential direction D 1. The circumferential stopper 40A 1 is provided on a downstream side of the first mounting arm 32A in the driving rotational direction D 11. The circumferential stopper 40B 1 is in contact with the second mounting arm 32B in the circumferential direction D 1. The circumferential stopper 40B 1 is provided on a downstream side of the second mounting arm 32B in the driving rotational direction D 11. The circumferential stopper 40C 1 is provided with the third mounting arm 32C in the circumferential direction D 1. The circumferential stopper 40C 1 is provided on a downstream side of the third mounting arm 32C in the driving rotational direction D 11. The circumferential stopper 40D 1 is in contact with the fourth mounting arm 32D in the circumferential direction D 1.The circumferential stopper 40D 1 is provided on a downstream side of the fourth mounting arm 32D in the driving rotational direction D 11.The guide 40B 2 is provided in the mounting groove 32B 1. The guide 40C 2 is provided in the mounting groove 32C 1. The guide 40D 2 is provided in the mounting groove 32D 1. The second connection member 40B may be adhered to the second attachment arm 32B with an adhesive material such as an adhesive. The third connection member 40C may be adhered to the third attachment arm 32C with an adhesive material such as an adhesive. The fourth connection member 40D may be adhered to the fourth attachment arm 32D with an adhesive material, e.g., an adhesive.The movable member 26 is a member separate from the fixing member 28. The movable member 26 is made of a first material. The fastener 28 is made of a second material. The second material is different from the first material. Examples of the first material are a metallic material such as iron. Examples of the second material include a metallic material such as an aluminum alloy and a nonmetallic material such as carbon. In this embodiment, the movable member 26 is a member separate from the sprocket unit 12. However, the movable member 26 may be provided at least partially integrally with the sprocket unit 12 as a one-piece member.As seen in FIG. 6, the plurality of teeth 36 includes a plurality of first teeth 36A and a plurality of second teeth 36B. The first teeth 36A and the second teeth 36B are alternately arranged in the circumferential direction D 1.As seen in FIG. 7, the first tooth 36A extends radially outward from the sprocket ring 34 to be accommodated only in an outer connection space C 11 of the bicycle chain C. The external connection space C 11 is provided between an opposing pair of external connection plates C 1. The first tooth 36A has a first maximum axial width MW 1 defined in the axial direction D 2. The first tooth 36A includes a first axial surface 36A 1 and a first axial mating surface 36A 2. The first axial surface 36A 1 faces in the axial direction D 2. The first axial opposing surface 36A 2 faces in the axial direction D 2 and is provided on a rear side of the first axial surface 36A 1. The first maximum axial width MW 1 is defined between the first axial surface 36A 1 and the first axial opposing surface 36A 2 in the axial direction D 2. The first tooth 36A has a first central plane 36A 3 bisecting the first maximum axial width MW 1 in the axial direction D 2. The first central plane 36A 3 is perpendicular to the rotational central axis A 1.As seen in FIG. 8, the second tooth 36B extends radially outward from the sprocket ring 34 to be accommodated only in an inner connection space C 21 of the bicycle chain C. The internal connection space C 21 is provided between opposing pairs of internal connection plates C 2. The second tooth 36B has a second maximum axial width MW 2 defined in the axial direction D 2. The second tooth 36B includes a second axial surface 36B 1 and a second axial mating surface 36B 2. The second axial surface 36B 1 faces in the axial direction D 2. The second axial opposing surface 36B 2 faces in the axial direction D 2, and is provided on a rear side of the second axial surface 36B 1. The second maximum axial width MW 2 is defined between the second axial surface 36B 1 and the second axial opposing surface 36B 2 in the axial direction D 2. The second tooth 36B has a second central plane 36B 3 bisecting the second maximum axial width MW 2 in the axial direction D 2. The second central plane 36B 3 is perpendicular to the rotational central axis A 1. In this embodiment, the second center plane 36B 3 is congruent with the first center plane 36A 3 in the axial direction D 2. However, the second center plane 36B 3 may be offset from the first center plane 36A 3 in the axial direction D 2.The first maximum axial width MW 1 is larger than the second maximum axial width MW 2. The first maximum axial width MW 1 is smaller than an axial width of the outer communication space C 11 and larger than an axial width of the inner communication space C 21. The second maximum axial width MW 2 is smaller than the axial width of the internal communication space C 21. However, the first maximum axial width MW 1 may be equal to or less than the second maximum axial width MW 2.As seen in FIGS. 4 and 5, the crank arm 16 includes a first internal spline 16A. The crank axle 14 includes a first external spline 14D at the first axle end 14A. The first external spline 14D meshes with the first internal spline 16A to integrally rotate the crank axle 14 with the crank arm 16.As seen in FIG. 9, the bicycle crank assembly 10 includes a torque transmitting member 42 to transmit the pedaling torque T 1 (FIG. 6 ) from the crank axle 14 to the sprocket 18. The torque transmitting member 42 is provided between the crank axle 14 and the movable member 26 to transmit the pedal operation torque T 1 (FIG. 6 ) between the crank axle 14 and the movable member 26.The torque transmission member 42 is connected to one of the crank axle 14 and the movable member 26 so as to be fixed with respect to one of the crank axle 14 and the movable member 26 in the axial direction D 2. The torque transmission member 42 is connected to the other of the crank axle 14 and the movable member 26 so as to be movable with respect to the other of the crank axle 14 and the movable member 26 in the axial direction D 2.In this embodiment, the torque transmission member 42 is connected to the crank axle 14 so as to be fixed in the axial direction D 2 with respect to the crank axle 14. The torque transmission member 42 is connected to the movable member 26 to be movable in the axial direction D 2 with respect to the movable member 26. The torque transmitting member 42 is fixed with respect to the crank axis 14 and is movable with respect to the movable member 26 in the axial direction D 2. However, the torque transmitting member 42 may be connected to the movable member 26 in the axial direction D 2 to be stationary with respect to the movable member 26. The torque transmitting member 42 may be connected to the crank axle 14 to be movable with respect to the crank axle 14 in the axial direction D 2. The torque transmitting member 42 may be movable with respect to the crank axis 14 and fixed with respect to the movable member 26 in the axial direction D 2.As seen in FIGS. 9 and 10, the movable member 26 has a groove 44 extending in the axial direction D 2. The torque transmitting member 42 is provided in the groove 44 so as to be slidable along the groove 44. The groove 44 is provided on an outer circumferential surface of the movable member 26. The groove 44 extends in the axial direction D 2 from the second end 26B toward the first end 26A.As seen in FIG. 9, the torque transmitting member 42 has a first axial length L 11. The groove 44 has a second axial length L 12. The second axial length L 12 is greater than the first axial length L 11. The torque transmitting member 42 has a first radial length L 21. The groove 44 has a second radial length L 22. The first radial length L 21 is greater than the second radial length L 22. However, the second axial length L 12 may be equal to or less than the first axial length L 11. The first radial length L 21 may be equal to or less than the second radial length L 22.As seen in FIG. 11, the torque transmitting member 42 includes a first surface 42A and a second surface 42B. The first surface 42A faces in the circumferential direction D 1 of the rotational center axis A 1. The second surface 42B is directed in the circumferential direction D 1 of the rotational center axis A 1. The second surface 42B is provided on the back side of the first surface 42A in the circumferential direction D 1.At least one of the first surface 42A and the second surface 42B is inclined with respect to a reference plane RP 1 parallel to the axial direction D 2. The reference plane RP 1 extends radially outward from the rotational center axis A 1. In this embodiment, the first surface 42A and the second surface 42B are inclined with respect to the reference plane RP 1. However, at least one of the first surface 42A and the second surface 42B may be parallel to the reference plane RP 1.The movable member 26 includes a first receiving surface 44A and a second receiving surface 44B. The first receiving surface 44A faces in the circumferential direction D 1. The first receiving surface 44A may be contacted with the first surface 42A. The second receiving surface 44B faces the first receiving surface 44A in the circumferential direction D 1. The second receiving surface 44B may be contacted with the second surface 42B. The first receiving surface 44A and the second receiving surface 44B at least partially form the groove 44. in this embodiment, the movable member 26 includes an additional surface 44C. The first receiving surface 44A, the second receiving surface 44B, and the additional surface 44C form the groove 44.At least one of the first receiving surface 44A and the second receiving surface 44B is inclined with respect to the reference plane RP 1. A circumferential distance CW 2 is defined between the first receiving surface 44A and the second receiving surface 44B in the circumferential direction D 1. The first receiving surface 44A and the second receiving surface 44B are inclined relative to each other to increase the circumferential distance CW 2 from a radially inner side to a radially outer side of the groove 44. In this embodiment, the first receiving surface 44A and the second receiving surface 44B are inclined with respect to the reference plane RP 1. However, at least one of the first receiving surface 44A and the second receiving surface 44B may be parallel to the reference plane RP 1.As seen in FIG. 12, the first surface 42A and the first receiving surface 44A are inclined with respect to the reference plane RP 1 by a first inclination angle AG 1. The second surface 42B and the second receiving surface 44B are inclined with respect to the reference plane RP 1 by a second inclination angle AG 2. The second inclination angle AG 2 is substantially equal to the first inclination angle AG 1. However, the second inclination angle AG 2 may deviate from the first inclination angle AG 1. An inclination angle of the first surface 42A may be different from an inclination angle of the first receiving surface 44A. An inclination angle of the second surface 42B may be different from an inclination angle of the second receiving surface 44B. In this embodiment, the first inclination angle AG 1 and the second inclination angle AG 2 are each about 3 degrees. However, the first inclination angle AG 1 and the second inclination angle AG 2 are not limited to this embodiment.The torque transmitting member 42 includes a radially outer surface 42C and a radially inner surface 42D. The radially outer surface 42C is directed radially outward. The radially inner surface 42D is directed radially inward. The radially inner surface 42D is radially provided on a rear side of the radially outer surface 42C. The first surface 42A and the second surface 42B are inclined relative to each other to increase a circumferential width CW 1 of the torque transmitting member 42 from the radially inner surface 42D toward the radially outer surface 42C. However, the first surface 42A and the second surface 42B may be parallel to each other.A gap G 1 is provided between the torque transmitting member 42 and the movable member 26 in the radial direction D 3 of the rotational center axis A 1. The gap G 1 is provided between the radially inner surface 42D and the additional surface 44C of the groove 44 in the radial direction D 3. Thus, the torque transmitting member 42 is spaced from the additional surface 44C of the groove 44.The torque transmitting member 42 includes a first additional surface 42E and a second additional surface 42F. The first additional surface 42E is directed in the circumferential direction D 1 of the rotational center axis A 1. The second additional surface 42F is directed in the circumferential direction D 1. The second additional surface 42F is provided on the back side of the first additional surface 42E in the circumferential direction D 1.The first additional surface 42E is provided between the first surface 42A and the radially outer surface 42C. The second additional surface 42F is provided between the second surface 42B and the radially outer surface 42C. The first additional surface 42E and the second additional surface 42F are parallel to the reference plane RP 1. The first surface 42A is inclined with respect to the first additional surface 42E. The second surface 42B is inclined with respect to the second additional surface 42F. However, at least one of the first additional surface 42E and the second additional surface 42F may be inclined with respect to the reference plane RP 1.The crank axle 14 includes a support groove 46. The support groove 46 includes a first support surface 46A, a second support surface 46B, and a third support surface 46C. The first support surface 46A is directed in the circumferential direction D 1. The first support surface 46A is in contact with the first additional surface 42E. The second support surface 46B is directed in the circumferential direction D 1. The second support surface 46B is in contact with the second additional surface 42F. The third support surface 46C is directed radially outward. The third support surface 46C faces the radially outer surface 42C of the torque transmitting member 42. The first support surface 46A and the second support surface 46B are parallel to the reference plane RP 1. However, at least one of the first support surface 46A and the second support surface 46B may be inclined with respect to the reference plane RP 1. The first support surface 46A, the second support surface 46B, and the third support surface 46C form the support groove 46A and the support groove 46, respectively.As seen in FIG. 9, the crank axle 14 includes an inner circumferential surface 14P, an inner wall 14W, and an inner groove 14G. The inner circumferential surface 14P at least partially defines the interior space 14S. The inner wall 14W extends radially inward from the intermediate portion 14C. The inner wall 14W has an annular shape extending along the inner circumferential surface 14P around the rotational center axis A 1. The inner wall 14W is provided at one end of the support groove 46. The inner wall 14W may be contacted with the torque transmitting member 42 to limit axial movement of the torque transmitting member 42 relative to the crank axis 14 in the axial direction D 2. The inner groove 14G is provided on the inner circumferential surface 14P and extends along the inner circumferential surface 14P around the rotational center axis A 1. The support groove 46 is provided between the inner wall 14W and the inner groove 14G in the axial direction D 2.As seen in FIGS. 9 and 10, the bicycle crank assembly 10 includes a snap ring 47. The snap ring 47 is inserted into the inner groove 14G of the crank axle 14. The torque transmission member 42 is provided between the inner wall 14W and the snap ring 47 in the axial direction D 2. The inner wall 14W and the retaining ring 47 limit the axial movement of the torque transmitting member 42 with respect to the crank axis 14 in the axial direction D 2. Thus, the torque transmitting member 42 is fixed with respect to the crank axis 14 in the axial direction D 2 when the movable member 26 is moved with respect to the crank axis 14 in the axial direction D 2.As seen in FIG. 12, the bicycle crank assembly 10 further includes an adjustment structure 48. the adjustment structure 48 is configured to change a radial position of the torque transmitting member 42 relative to the groove 44. The adjustment structure 48 is accessible from outside the crank axle 14.In this embodiment, the adjustment structure 48 includes an adjustment screw 50. the adjustment screw 50 has an externally threaded portion 50A and a contact end 50B. The crank axle 14 has an externally open threaded adjustment bore 14E. The adjustment screw 50 is threadably engaged with the adjustment threaded bore 14E. The contact end 50B is engaged with the torque transmitting member 42. The torque transmitting member 42 includes a receiving recess 42G. The contact end 50B is provided in the receiving recess 42G. The adjustment screw 50 includes a tool receiving portion 50C, such as a hexagonal bore. The tool engagement portion 50C is accessible from outside the crank axle 14.By rotating the adjustment structure 48, the adjustment structure 48 is displaced radially with respect to the crank axis 14. The torque transmitting member 42 is inserted into the groove 44 of the movable member 26 when the adjusting structure 48 is moved toward the groove 44.As seen in FIG. 9, the bicycle crank assembly 10 further includes a slide structure 52 provided between the torque transmitting member 42 and the groove 44. In this embodiment, the sliding structure 52 includes a first rolling element 52A and a second rolling element 52B. The first rolling element 52A and a second rolling element 52B are in contact with the additional surface 44C of the groove 44. The torque transmitting member 42 has a first bore 42X and a second bore 42Y. The first rolling element 52A is rotatably provided in the first bore 42X. The second rolling element 52B is rotatably provided in the second bore 42Y. However, the sliding structure 52 may include another member instead of or in addition to the first and second rolling members 52A and 52B.The bicycle crank assembly 10 further includes a biasing member 54 to bias the slide structure 52 toward the groove 44. The biasing member 54 is disposed in the torque transmitting member 42. In this embodiment, the biasing member 54 includes a first spring 54A and a second spring 54B. The first spring 54A is provided in the first hole 42X to bias the first rolling element 52A against the additional surface 44C of the groove 44. The second spring 54B is provided in the second hole to bias the second rolling element 52B against the additional surface 44C of the groove 44. However, the biasing member 54 may include another member instead of the first and second springs 54A and 54B. The biasing member 54 may be provided at a position other than the inner side of the torque transmission member 42.As seen in FIGS. 9 and 10, the bicycle crank assembly 10 includes a bearing structure 56. the bearing structure 56 is radially disposed between the movable member 26 and the crank axis 14 about the rotational center axis A 1. The bearing structure 56 is disposed between the movable member 26 and the crank shaft 14 to support the movable member 26 slidably in the axial direction D 2. The bearing structure 56 is disposed at a position other than that of the torque transmission member 42 in the axial direction D 2. In the depicted embodiment, the bearing structure 56 is spaced apart from the torque transmitting member 42 in the axial direction D 2. However, the bearing structure 56 may be arranged partially overlapping with the torque transmission element 42 in the axial direction D 2.As seen in FIG. 9, the bearing structure 56 includes a plurality of bearings 58 and a holder 60. the plurality of bearings 58 are rotatably disposed between the crank axis 14 and the movable member 26 in the radial direction about the rotational center axis A 1. The plurality of bearings 58 are in contact with the crank axle 14 and the movable member 26. The holder 60 is provided between the crank axis 14 and the movable member 26 to support the plurality of bearings 58 in the radial direction about the rotational center axis A 1. The holder 60 has a tubular shape. The holder 60 rotatably supports the plurality of bearings 58 with respect to the crank axis 14 and the movable member 26. The holder 60 includes a plurality of holder holes 60A. The bearings 58 are rotatably supported in the holder holes 60A.The movable member 26 is movable with respect to the crank axis 14 in a movable range MR 1 in the axial direction D 2. The bearing structure 56 is movable with respect to the crank axis 14 in a bearing movement range MR 2 in the axial direction D 2. In this embodiment, the bearing movement range MR 2 is smaller than the movement range MR 1 of the movable member 26. the bearing movement range MR 2 is equal to or larger than 50% of the movement range MR 1 of the movable member 26. The bearing movement range MR 2 may be less than 50% of the movement range MR 1.As seen in FIGS. 9 and 10, the bicycle crank assembly 10 includes a bearing retaining ring 62. The bearing retaining ring 62 is fixed to the movable member 26 to limit axial movement of the bearing structure 56 toward the groove 44 in the axial direction D 2.As seen in FIG. 9, the bicycle crank assembly 10 includes an additional support structure 63. the additional support structure 63 is fixed to the first shaft end 14A of the crank shaft 14 to movably support the movable member 26 with respect to the crank shaft 14 in the axial direction D 2. The additional bearing structure 63 includes a slide bush 63A and a seal ring 63B. The slide bush 63A is fixed to the first shaft end 14A of the crank shaft 14 to movably support the movable member 26 with respect to the crank shaft 14 in the axial direction D 2. The seal ring 63B is fixed to the slide bush 63A. The additional bearing structure 63 can be omitted in the bicycle crank assembly 10.In this embodiment, as seen in FIG. 13, the bearing structure 56 is provided between the first axis end 14A and the torque transmitting member 42 in the axial direction D 2. The bearing structure 56 is provided between the crank arm 16 and the torque transmitting member 42 in the axial direction D 2. The bicycle crank assembly 10 has an axial center plane CP 1 perpendicular to the rotational center axis A 1. The axial center plane CP 1 bisects an axial maximum width W 1 of the bicycle crank assembly 10. However, the bearing structure 56 may be provided on a left side with respect to the axial center plane CP 1. The bearing structure 56 may be provided between the second axle end 14B and the torque transmitting member 42. The bearing structure 56 may be provided between the additional crank arm 20 and the torque transmitting member 42 in the axial direction D 2. The bearing structure 56 and the torque transmitting member 42 are provided on a first side S 1 with respect to the axial center plane CP 1. The first axis end 14A of the crank axis 14 is provided on the first side S 1 with respect to the axial center plane CP 1. The second axial end 14B of the crank axle 14 is provided on a second side S 2 with respect to the axial center plane CP 1. The second side S 2 is defined on an opposite side to the first side S 1 with respect to the axial center plane CP 1 in the axial direction D 2. However, the bearing structure 56 may be provided on one of the first side S 1 and the second side S 2, and the torque transmitting member 42 may be provided on the other of the first side S 1 and the second side S 2.As seen in FIGS. 10 and 11, the bicycle crank assembly 10 further includes a bushing member 64. the bushing member 64 is circumferentially disposed with the torque transmitting member 42. The bushing member 64 includes a slit 64S extending in the axial direction D 2. The torque transmitting member 42 is provided in the slot 64S. The bushing member 64 is provided between the crank axle 14 and the movable member 26. The bushing element 64 is fixed to the crank axle 14 and is slidable with the movable element 26.In this embodiment, the bushing member 64 includes a first circumferential end 64A and a second circumferential end 64B. The bushing member 64 extends circumferentially between the first circumferential end 64A and the second circumferential end 64B. The slot 64S is provided between the first circumferential end 64A and the second circumferential end 64B. The torque transmitting member 42 is provided between the first circumferential end 64A and the second circumferential end 64B. However, the bushing member 64 may be omitted from the bicycle crank assembly 10. The bushing member 64 may have an annular shape in a case where the bushing member 64 is offset from the torque transmitting member 42 in the axial direction D 2. In this embodiment, the bushing member 64 is integrally provided as a one-piece, unitary member. However, the bushing member 64 may include multiple separate members.As seen in FIG. 12, a first additional gap G 21 and a second additional gap G 22 are provided radially between the crank axis 14 and the movable member 26. The first additional gap G 21 is provided between the torque transmission member 42 and the first circumferential end 64A in the circumferential direction D 1. The second additional gap G 22 is provided between the torque transmitting member 42 and the second circumferential end 64B in the circumferential direction D 1.As seen in FIG. 14, the bush member 64 is provided between the inner wall 14W and the retaining ring 47 in the axial direction D 2. The inner wall 14W and the retaining ring 47 limit the axial movement of the bushing member 64 in the axial direction D 2 with respect to the crank axis 14, and thus the bushing member 64 is fixed with respect to the crank axis 14 in the axial direction D 2 when the movable member 26 is moved with respect to the crank axis 14 in the axial direction D 2.The bushing member 64 divides the internal space 14S into a first space 14S 1 and a second space 14S 2 in the axial direction D 2. A volume of the first space 14S 1 and the second space 14S 2 varies depending on the axial movement of the movable member 26 with respect to the crank axis 14.As seen in FIG. 13, the sprocket unit 12 has a reference surface 12A perpendicular to the rotational center axis A 1. The pedal attachment end 22 has an axially outermost surface 22B. The fastener 28 has the reference surface 12A. In this embodiment, the reference surface 12A is an axially outermost surface of the sprocket unit 12.The movable member 26 is provided movably with respect to the crank axis 14 to move the sprocket unit 12 from an axially outward position P 11 to an axially inward position P 12 in the axial direction D 2 of the rotational center axis A 1. The reference surface 12A is provided in an axial position that is equal to an axial position of the axially outwardmost surface 22B in a state where the sprocket unit 12 is in the axially outward position P 11, or is disposed axially inward from the axially outermost surface 22B in the axial direction D 2 in the state where the sprocket unit 12 is in the axially outward position P 11.In this embodiment, the reference surface 12A is positioned axially inward from the axially outermost surface 22B in the axial direction D 2 in the state where the sprocket unit 12 is located at the axially outward position P 11. However, the reference surface 12A may be configured to be positioned at an axial position equal to an axial position of the axially outwardmost surface 22B in the state where the sprocket unit 12 is at the axially outward position P 11.The reference surface 12A is movable relative to the crank arm 16 from the axially inward position P 12 to the axially outward position P 11 without exceeding the reference surface 12A axially outward. The movable range MR 1 of the movable member 26 is defined between the axially outward position P 11 and the axially inward position P 12 as the maximum movable range of the sprocket unit 12. The axially outward position P 11 may therefore also be referred to as the axially outwardmost position P 11. The axially inward position P 12 may also be referred to as the axially innermost position P 12.As seen in FIG. 13, the bicycle crank assembly 10 includes a stopper structure 65. the stopper structure 65 is provided in the inner space 14S of the crank axle 14 to limit axial movement of the movable member 26 relative to the crank axle 14 between the axially outward position P 11 and the axially inward position P 12.The stopper structure 65 includes a first stopper 66 and a second stopper 67. The first stopper 66 is connected to the movable member 26 to move with respect to the crank axis 14 together with the movable member 26 in the axial direction D 2. The second stopper 67 is connected to the crank shaft 14.As seen in FIG. 10, the first stopper 66 includes a first stopper body 68 and a first receiving member 70. the first stopper body 68 is fixed to the movable member 26. The first stopper body 68 is fixed to the second end 26B of the movable member 26. As seen in FIG. 3, the first stopper body 68 extends from the second end 26B of the movable member 26 toward the second axis end 14B.As seen in FIG. 9, the first receiving member 70 is fixed to the movable member 26. The first receiving member 70 is held between the first stopper body 68 and the second end 26B of the movable member 26. The first receiving member 70 is made of an elastic member such as rubber. The first receiving member 70 can be brought into contact with the inner wall 14W. The sprocket unit 12 is provided in the axially outward position P 11 in a state where the first receiving member 70 comes / is in contact with the inner wall 14W.As seen in FIGS. 3 and 15, the second plug 67 includes a cap 72, a rod 76, a second elastic member 78, and the cap 72 is fixed to the second axis end 14B of the crank axis 14 to cover the second end opening 14B 1 of the second axis end 14B. The rod 76 is fixed to the cap 72 and extends from the cap 72 toward the movable member 26 in the axial direction D 2. The second elastic member 78 is fixed to one end of the rod 76. The second elastic member 78 can be brought into contact with the first stopper 66. In this embodiment, the second elastic member 78 can be brought into contact with the first stopper body 68. As seen in FIG. 3, the sprocket unit 12 is positioned at the axially inward position P 12 in a state where the second elastic member 78 comes / is in contact with the first stopper body 68 of the first stopper 66.As seen in FIG. 16, when the bicycle chain C is in a first inclination state ST 1 in which the bicycle chain C is inclined with respect to the first and second center planes 36A 3 and 36B 3 in the first axial direction D 21, the sprocket 12 (the sprocket 18) receives a first axial force F 1 in a first axial direction D 21. Thus, when the bicycle chain C is in the first inclined state ST 1, the sprocket unit 12 (the sprocket 18) moves in the first axial direction D 21 with respect to the crank axis 14 due to the first axial force F 1. This reduces an inclination angle AG 31 of the bicycle chain C. The first inclination state ST 1 occurs, for example, when the bicycle chain C is engaged with the sprocket 18 and a smallest sprocket (not shown). The first axial direction D 21 extends along the axial direction D 2.The sprocket unit 12 (the sprocket 18) receives a second axial force F 2 in a second axial direction D 22 when the bicycle chain C is in a second inclination state ST 2 in which the bicycle chain C is inclined with respect to the first and second center planes 36A 3 and 36B 3 in the second axial direction D 22. Thus, when the bicycle chain C is in the second inclined state ST 2, the sprocket unit 12 (the sprocket 18) moves in the second / second axial direction(s) D 22 with respect to the crank axis 14 due to the second axial force F 2. This reduces an inclination angle AG 32 of the bicycle chain C. The second inclination state ST 2 occurs, for example, when the bicycle chain C is engaged with the sprocket 18 and a largest rear sprocket (not shown). The second axial direction D 22 extends along the axial direction D 2 and is opposite to the first axial direction D 21.The term "comprising" and its derivatives, as used herein, are to be understood as open ended terms that specify the presence of stated features, elements, components, groups, integers, and / or steps, but do not preclude the presence of other unstated features, elements, components, groups, integers, and / or steps. The foregoing also applies to words having similar meanings, such as the terms "with", "having", and their derivatives.The terms "member", "section", "portion", "part", "element", "body" and "structure", when used in the singular, may have the dual meaning of a single part or multiple parts.The ordinal numbers such as "first", "second" mentioned in the present application are merely identifiers, but have no other meaning such as a certain order or the like. Moreover, for example, the term "first element" itself does not imply the existence of a "second element", and the term "second element" itself does not imply the existence of a "first element".The term "pair of" as used herein may include the configuration in which the pair of elements have different shapes or structures from each other, in addition to the configuration in which the pair of elements have the same shapes or structures.The terms "a" (or "an"), "one or more", and "at least one" may be used interchangeably herein.Finally, the terms of extent such as "substantially", "about" and "about" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. All numerical values described in this application may be construed to include "substantially", "around", and "about".Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims

A bicycle crank assembly (10) comprising: a sprocket (18) having a rotational center axis (A1); a crank axis (14) extending along the rotational center axis (A1), the crank axis (14) having an interior space (14S); a movable member (26) movably provided in the interior space (14S) and further connected to the sprocket to move with the sprocket 18 relative to the crank axis 14 in the axial direction (D2) of the rotational center axis (A1); a torque transmission member (42) for transmitting a pedal operation torque from the crank axis (14) to the sprocket (18); and a bearing structure (56) disposed between the movable member (26) and the crank shaft (14) to support the movable member (26) slidably in the axial direction (D2), wherein the bearing structure (56) is disposed at a position different from a position of the torque transmitting member (42) in the axial direction (D2).The bicycle crank assembly (10) according to claim 1, further comprising: a crank arm (16) fixed to the crank axle (14); wherein the torque transmitting member (42) is connected to the crank axle (14) to be fixed with respect to the crank axle (14) in the axial direction (D2), or wherein the torque transmitting member (42) is connected to the movable member (26) to be fixed with respect to the movable member (26) in the axial direction (D2).The bicycle crank assembly (10) according to claim 1 or 2, wherein the torque transmitting member (42) is fixed with respect to the crank axis (14) and movable with respect to the movable member (26) in the axial direction (D2).The bicycle crank assembly (10) according to claim 3, wherein the movable member (26) has a groove (44) extending in the axial direction (D2), and the torque transmitting member (42) is provided in the groove (44) to be slidable along the groove (44).The bicycle crank assembly (10) according to claim 4, wherein the torque transmitting member (42) includes a first surface (42A) facing in a circumferential direction of the rotational center axis (A1) and a second surface facing in a circumferential direction, the second surface (42B) being provided on a rear side of the first surface (42A) in the circumferential direction.The bicycle crank assembly (10) according to claim 5, wherein the movable member (26) comprises a first receiving surface (44A) that faces in the circumferential direction, the first receiving surface (44A) being contactable with the first surface (42A), and a second receiving surface (44B) that faces the first receiving surface (42A) in the circumferential direction, the second receiving surface (44B) being contactable with the second surface (42B), and the first receiving surface (44A) and the second receiving surface (44B) at least partially form the groove (44).The bicycle crank assembly (10) according to claim 5, wherein at least one of the first surface (42A) and the second surface (42B) is inclined with respect to a reference plane parallel to the axial direction (D2), the reference plane extending radially outward from the rotational center axis (A1).The bicycle crank assembly (10) according to claim 5, 6 or 7, wherein the torque transmitting member (42) comprises a radially outer surface (42C) directed radially outward and a radially inner surface (42D) directed radially inward, the radially inner surface (42D) being radially provided on a rear side of the radially outer surface (42C), and the first surface (42A) and the second surface (42B) being inclined relative to each other to increase (42C) a circumferential width of the torque transmitting member (42) from the radially inner surface (42D) to the radially outer surface.The bicycle crank assembly (10) according to any one of claims 4 to 8, further comprising an adjustment structure (48) configured to change a radial position of the torque transmitting member (42) relative to the groove (44), wherein the adjustment structure (48) is preferably accessible from outside the crank axis (14).The bicycle crank assembly (10) according to any one of claims 4 to 9, further comprising a sliding structure (52) provided between the torque transmitting member (42) and the groove (44).The bicycle crank assembly (10) of claim 10, further comprising a biasing member (54) to bias the sliding structure (52) toward the groove (44), wherein the biasing member (54) is preferably disposed in the torque transmitting member (42).The bicycle crank assembly (10) according to any one of claims 4 to 11, wherein a gap is provided between the torque transmission member (42) and the movable member (26) in the radial direction of the rotational center axis (A1).The bicycle crank assembly (10) according to any one of claims 1 to 12, wherein the crank axle (14) comprises a first axle end (14A) and a second axle end (14B), wherein the crank axle (14) extends along the rotational center axis (A1) between the first axle end (14A) and the second axle end (14B), and the bearing structure (56) is provided between the first axle end (14A) and the torque transmitting member (42).The bicycle crank assembly (10) according to any one of claims 1 to 13, wherein the movable member (26) is movable with respect to the crank axis (14) in the axial direction (D2) in a range of motion, wherein the bearing structure (56) is movable with respect to the crank axis (14) in the axial direction (D2) in a bearing range of motion (MR2), and the bearing range of motion (MR2) is smaller than the range of motion (MR1) of the movable member (26), wherein the bearing range of motion (MR2) is preferably equal to or greater than 50% of the range of motion (MR1) of the movable member (26).The bicycle crank assembly (10) according to any one of claims 1 to 14, further comprising a bushing member (64) circumferentially arranged with the torque transmitting member (42), wherein the bushing member (64) preferably has a slot (64S) extending in the axial direction (D2), and the torque transmitting member (42) is provided in the slot (64S).The bicycle crank assembly (10) according to claim 1, wherein the sprocket unit (12) has a reference surface (12A) perpendicular to the rotational center axis (A1), the reference surface (12A) being an axially outermost surface of the sprocket unit (12); further comprising a crank arm (16) having a pedal attachment end with an axially outermost surface, and wherein the movable member (26) is provided movable with respect to the crank axis (14) to move with the sprocket unit (12) from an axially outward position (P11) to an axially inward position (P12) in an axial direction (D2) of the rotational center axis (A1), the reference surface (12A) being provided in an axial position, which is equal to an axial position of the axially outwardmost surface (22B) in a state where the sprocket unit (12) is in the axially outward position (P 11), or is disposed axially inward of the axially outermost surface (22B) in the axial direction (D 2) in the state where the sprocket unit (12) is in the axially outward position (P 11).

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