Abstract: A bicycle crank arm assembly is provided with a bicycle crank arm with a first end configured to be coupled to an axle of a bottom bracket and a second end with a pedal attachment bore for receiving a bicycle pedal shaft. A tubular member is press fitted into the bore of the bicycle crank arm. The tubular member has an external circumferential with serrations that is surface non-releasably press fitted into the pedal attachment bore of the bicycle crank arm, and an internally threaded surface adapted to be coupled to the bicycle pedal shaft. The crank arm preferably has a counterbore at one axial end of the pedal attachment bore with a washer disposed therein such that the washer partially overlaps the tubular member.

Abstract: A crank assembly formed as a unitary composite structure, the crank arms and crank shaft being hollow to provide maximum weight reduction, the crank arms being over-sized to provide the necessary stiffness and strength. The unitary composite crank assembly may further include a crank claw integrally formed with the crank assembly. Additionally, a spider may be integrally formed with the crank assembly reducing the amount of parts for the assembly, increasing stiffness and reducing overall weight.

Abstract: A crank arm assembly for a bicycle, comprising a crank arm and an element for transferring torque from the crank arm to a bicycle chain. The crank arm (and the element for transferring torque respectively comprise first and second front coupling means provided with respective matching profiles adapted to be coupled together to transfer torque from the crank arm to the element for transferring torque. In particular, the first and second means for transferring torque comprise respective front toothings, preferably Hirth toothings.

Abstract: In combination with a crank assembly, the improvement comprising an apparatus for improving operation of the crank assembly. The apparatus includes an elongated extension member having each of a predetermined shape, a first predetermined length and formed of a first predetermined material, such predetermined shape includes a projection on one end thereof for engagement with one end of the crank assembly. A rotatable handle member is disposed around at least a portion of the elongated extension member, such rotatable handle member having a second predetermined length and formed of a second predetermined material. There is a means for securing the rotatable handle member to the elongated handle member.

Abstract: The invention relates to an assembly structure of treading crank and spindle tube of the bike; wherein circularly set several convex straight ribs, with even intervals, on the inner surface of the treading crank, and there is a reserved circular space between each convex straight rib and the bottom surface of the central hole. Several circularly arranged sunken-shaped cavernous-straight troughs are set on the section of the end surface; when combining treading crank and spindle tube, make use of a suitable size of cone-expanding body and set the big bottom of said cone-expanding body at the bottom surface; then push said several cavernous-straight troughs set on the end surface of the spindle tube toward the direction of the section the convex straight ribs; said several cavernous-straight troughs will move outwardly and into the circular space between convex straight rib and the bottom surface and then to be locked.

Abstract: A right crank arm assembly for a bicycle, comprises a right crank arm and at least one front sprocket coupled with the crank arm at at least one coupling portion of the crank arm. The front sprocket has an inner side adapted, in use, to face towards the frame of the bicycle and an outer side opposite the inner side. The assembly comprises at least one first crank arm element which acts in contact with the front sprocket on one of said sides and at least one second crank arm element which acts in contact with the front sprocket on the other of said sides. The contact action of the crank arm elements on the two opposite sides of the front sprocket prevents the twisting deformation of the front sprocket during pedaling. Such a deformation would cause a reduction in the transmission efficiency of the right crank arm assembly.

Abstract: A bicycle crank comprises a mixture of aluminum and chromoly. The spine comprises chromoly, which serves as a backbone to the crank arm and thereby provides added strength. The body comprises aluminum, which reduces the crank arm weight. The body can therefore be thinner and lighter with the added support provided by the steel spine. In another embodiment the crank arm includes a spine having a crank boss and a spindle boss at opposed ends that are integrally formed with the crank arm. An outer shell includes an elongated member having an inner face having an outer perimeter with a shape approximately coincident with an outer perimeter of the spine The inner face is recessed to admit a portion of the spine and has crank and spindle boss apertures extending through to an outer face. The outer perimeters of the outer shell and the spine are joined together.

Abstract: A crank apparatus includes a driven member rotatably mounted to a machine, and a crank arm attached at an inner end thereof to the driven member at a rotational axis of the driven member such that the driven member and crank arm rotate together. An axle is slidably mounted to the crank arm such that the axle is maintained substantially parallel to the rotational axis of the driven member as it slides from an inner point on the crank arm, to an outer point on the crank arm, and a bias element is arranged to exert a force on the axle toward the rotational axis of the driven member.

Abstract: A pedal crank includes a crank arm having a hole formed in one end to receive one end of a crank shaft which may be rotatably attached to a bicycle frame. An expanding device may be engaged in the end of the crank shaft for expanding the crank shaft to engage with the crank arm, and to solidly secure the crank shaft to the crank arm. The crank arm and the crank shaft may include knurled surfaces for solidly engaged with each other. The expanding device includes a locking member engaged into the crank shaft and having an inclined outer peripheral surface for engaging with the crank shaft, and for expanding the crank shaft when the locking member is moved relative to the crank shaft.

Abstract: A crank device includes a crank arm having an opening formed in one end and defined by an outer peripheral fence for attaching to a crank shaft, and an orifice formed in another end and defined by an outer peripheral wall for coupling to a foot pedal, and the crank arm includes one or more apertures formed in the other end and formed in the outer peripheral wall for weight reducing purposes. The aperture may be laterally formed in the other end of the crank arm, or formed through the outer peripheral wall of the crank arm and communicating with the orifice of the crank arm. The crank arm may further include one or more depressions for further weight reducing purposes.

Abstract: A crankset that includes a first crank, a second crank, a first spindle portion, a second spindle portion, and an attachment assembly. Each of the first crank and the second crank include an end adapted to engage a pedal. The first spindle portion includes a first end coupled to the first crank and a second end that has a first engagement member defined by at least one protrusion and at least one cavity. The second spindle portion includes a first end coupled to the second crank and a second end that has a second engagement member defined by at least one protrusion and at least one cavity that are substantially mirror images of the at least one protrusion and the at least one cavity of the first spindle portion, and that engage the corresponding at least one cavity and the at least one protrusion of the first spindle portion.

Abstract: An improved mount for, and method of mounting an, optical structure is provided. The mount has a protruding member extending from a surface of the optical structure, a base element having a mounting structure for mounting the mount to another structure and an upper element extending from the base element having a first opening extending therethrough for receipt therein of at least a portion of the protruding member. The first opening defines first and second arms, each of the arms comprising a head portion and each of the head portions ending at an end. A second opening in the upper element extends through one of the head portions and the end thereof in a direction toward the other head portion, while a third opening exists in the upper element through the end of the other head portion in an orientation substantially opposite to and in communication with the second opening so that a tightening mechanism received through the second opening can be received into the third opening.

Abstract: A drive unit able to be applied to a vehicle with pedals, like a bicycle, a tricycle or other, having at least a flywheel and a pair of pedals connected to a central shaft rotatable around a rotation axis. The drive unit comprises an electric motor, fed by an electric feed member, motion transmission members, which connect the electric motor to the flywheel, and a control unit that detects, by means of corresponding sensors, the speed of rotation of the central shaft connected to the pedals in order to feed, in proportion thereto, the electric motor. The drive unit also comprises a first free wheel which connects the motion transmission members to the flywheel, and a second free wheel that connects the central shaft to the flywheel. Both the free wheels are disposed coaxial with the flywheel so as to rotate around the rotation axis.

Abstract: A bicycle crank arm assembly is disclosed, comprising a crank arm having a first end for coupling with a bottom bracket assembly and a second end for coupling with a pedal, at least one of the first end and the second end comprising a hole extending from a side of the crank arm for coupling with an axle of the pedal or of the bottom bracket assembly, respectively, further comprising a reinforcing element extending around the hole at the side of the crank arm, and constrained to the crank arm.

Abstract: A bicycle crank arm assembly is disclosed, comprising a crank arm having a first end for coupling with a bottom bracket assembly and a second end for coupling with a pedal, at least one of the first end and the second end comprising a hole extending from a side of the crank arm for coupling with an axle of the pedal or of the bottom bracket assembly, respectively, further comprising a reinforcing element extending around the hole in the proximity of the side of the crank arm, having a portion configured for receiving an abutment portion of the axle resting upon it, and wherein the crank arm and the reinforcing element contact along a respective surface not entirely contained within a plane perpendicular to an axis of the hole.

Abstract: A bicycle sprocket crank assembly is comprised of first and second crank arms joined to a spindle. One of the crank arms and the spindle may be fabricated as a unitary structure, or both cranks arms may be formed as separate structures and joined together. In either case the spindle has at least a first coupling end with an internally tapped axial bore defined therein and the second crank arm forms at least a first socket at its axle end. At least a first wedging sleeve is provided and is disposed about the first coupling end of the spindle. The first wedging sleeve conforms to the shapes of both the first coupling end of the spindle and the hollow cavity in the first socket. Either the coupling end of the spindle or the hollow cavity is axially tapered, and the wedging sleeve is tapered to match.

Abstract: A stationary exercise bicycle is provided having a frame, a resistance member, a drive assembly, a right pedal, a left pedal, a seat and an adjustable seat mechanism utilizing a rack. Assembly and disassembly of a three piece crank arm assembly is accomplished without requiring the assembling and disassembling of the entire drive assembly. The stationary exercise bicycle also provides a variety of users with an optimum seat position and with a convenient latch mechanism to adjust the position of the seat.

Abstract: A carbon fiber bicycle crank includes an axle lug, having a portion for receiving a crank axle. A foam core is coupled to the axle lug during a first molding process. A pedal engaging lug is coupled to the foam core after the completion of the first molding process, and a carbon fiber composite material exoskeleton is coupled to and disposed exteriorly of the axle lug, foam core and pedal lug.

Abstract: A bicycle pedal crank has an elongated body and a first end portion with a first seat for coupling with a bottom bracket of the bicycle, a second end portion with a second seat for coupling with a pedal, and an intermediate portion extending between the first end portion and said second end portion and having an inner portion substantially without structural strength and a first reinforcement structure. The first reinforcement structure has a tubular structure arranged around said inner portion and extending longitudinally not longer than the longitudinal extension of the intermediate portion. The extension of the tubular element is limited to the intermediate portion of the pedal crank. The crank may be manufactured in a simple, quick way in a completely automated manner, using a filling material molded under high pressure.

Abstract: A hollow crank arm for a bicycle comprising a body of elongated shape, at the ends of which are formed, respectively, an area for connection of the bottom bracket spindle and an area for connection of the pedal. The body includes a cavity of elongated shape and two solid end portions which are the aforesaid connection areas for the bottom bracket spindle and for the pedal. The crank arm is preferably formed through a forging process.

Abstract: The present invention relates to an auxiliary power unit starting apparatus for an electric bicycle, which can convert the rider's pedaling force into mechanical displacement at the time the bicycle is being pedaled, and then the mechanical displacement can start the auxiliary power unit of the electric bicycle. The device of the present invention has simple structure and small size, and it can be easily manufactured and assembled.

Abstract: A drive mechanism for a bicycle transmission assist mechanism includes a crank arm having a drive member. The drive member includes a first abutment facing a forward rotational direction of the crank arm and a non-concave sloped surface facing a rearward rotational direction of the crank arm.

Abstract: A shaft element of a bottom bracket assembly of a bicycle has a first end portion having a first coupling with another shaft element and a second end portion having a second coupling with a crank arm. The first coupling has a reference element and the second coupling has a coupling element with a predetermined angular position with respect to the reference element. The shaft element is can be coupled with a crank arm with a coupling with said shaft element, the coupling having a coupling element with a predetermined angular position with respect to a middle plane of the crank arm. The aforementioned shaft element and the aforementioned crank arm make it possible to precisely achieve a predetermined angular positioning between shaft element and crank arm at the time of assembly of a crank arm assembly and, therefore, an alignment at 180° between the crank arms at the time of assembly of a bottom bracket assembly.

Abstract: A bicycle crank arm apparatus includes an axle having a first end portion and a second end portion, wherein the first end portion has an outer peripheral surface and a threaded inner peripheral surface; an axle bolt having a threaded outer peripheral surface screwed into the threaded inner peripheral surface of the first end portion of the axle; a crank arm having an axle mounting boss defining an opening for receiving the first end portion of the axle therein, wherein the axle mounting boss includes a first fastener for tightening the crank arm mounting boss around the first end portion of the axle; and wherein the crank arm boss is positioned axially inwardly of the axle bolt.

Abstract: A crank assembly for a bicycle's bottom bracket assembly comprises a shaft extending along a longitudinal axis, at least one crank arm associated with at least one free end of said shaft, first front coupling means formed on said shaft and second front coupling means formed on said at least one crank arm, said first and second front coupling means being coupled together. In particular, the aforementioned first and second front coupling means comprise respective front toothings. The front coupling is located in an end zone, or on the outside, of a bottom bracket assembly's shaft's housing box formed in the bicycle's frame. The front coupling introduces a structural discontinuity between crank arm and shaft, for which reason the bending load exerted on the crank arm during pedaling is transmitted to the shaft to a small degree.

Abstract: A method for manufacturing a crank arm and spider assembly includes the following steps: (1) providing a blank; (2) shaping the blank to form a crank billet comprising an elongate body having a first end on which a spider is integrally formed and an opposite end having an expanded outside diameter; (3) forming a channel substantially co-extensive with the elongate body with an opening at the second end of the body; (4) reducing the expanded second end and thereby reducing inside diameter of the channel in proximity of the second for forming an entry of the channel; (5) filling a liquid into the channel through the entry and then sealing the entry; (6) placing the crank billet with the liquid filled in the channel into a mold and performing a mold forging operation to obtain a semi-product; and (7) forming a hole in the body to release the filling liquid out of the channel of the crank.

Abstract: A bicycle crank fixing structure is arranged to fix a left crank with a mounting bore and a slit extending radially from the mounting bore to a crank axle. The mounting bore is non-rotatably coupled to the crank axle. The slit is provided with two mounting bolts that perpendicularly intersect to adjust a width of the slit to fasten the crank to the crank axle. The crank axle has a retaining hole formed on the outer circumferential surface thereof which faces the slit of the crank. A retaining member with a retaining projection is disposed in the slit such that the retaining member rotates by rotation of the mounting bolt. The retaining projection of the retaining member is retained in the retaining hole formed on the crank axle to prevent the crank from detaching from the crank axle even when a fastening bolt is loosened.

Abstract: A crank structure for a bicycle pedal. A front outer thread of a cylindrical sleeve has a same rotary direction as an inner thread hole of the crank, and the rear outer thread has the opposite rotary direction to that of the front outer thread. The inner thread rotary direction of the cylindrical sleeve is the same as that of an outer thread of a bolt protruding from a pedal, and opposite edges of the two each has a hole, so that after the front outer thread of the cylindrical sleeve is secured to the thread of a threaded hole in the crank. A nut is used to lock the rear outer thread in order to limit the rotation. The bolt is locked into the inner thread of the hole of the cylindrical sleeve for the assembly in order to attain the effects of securely mounting and easily detaching the crank structure.

Abstract: A two-piece crank hanger set including a left crank arm having a tubular crank spindle attached thereto and a right crank arm having at least one chain sprocket wheel attached thereto. The crank spindle extends through a bicycle crank tube. Bearing cups are removably attached to both ends of the crank tube. Bearing retainers having tapered roller bearings engage the bearing cups. A tubular stop member is held in place on the outer end of the crank spindle by a spline mechanism. A preload and attachment bolt passes through the right crank arm and chain sprocket wheel and into threadable engagement with a threaded inner surface of the outer end of the tubular crank spindle. The preload and attachment bolt is tightened to preload the bearings.

Abstract: A bicycle crank is provided comprising an elongated core with a first and second end, a first and second insert are arranged at the ends of the core and a high-resistance coating of fibers incorporated in a plastic matrix material forms a coating for the core and inserts. The core is a preformed element and each insert is connected to the respective end of the core by a union element having recesses to establish a shape coupling with an insert and the respective end portion of the core.

Abstract: A bicycle crank mechanism comprises a main crank, a follower crank, and a connecting lever disposed between free ends of the main and follower cranks. A second fixed fulcrum shaft of the follower crank is arranged obliquely upwardly and backwardly of a first fixed fulcrum shaft of the main crank, the follower crank extending downward beyond a line connecting the first and second fixed fulcrum shafts from the second fixed fulcrum shaft such that the second free fulcrum shaft is swung below the line connecting the first and second fixed fulcrum shafts. A pedal is attached to a projection end of the lever and arranged in the vicinity of the free end of the main crank, the pedal being rotated along a non-circular track passing between the first and second fixed fulcrum shafts, and the first fixed fulcrum shaft being located at an internal area of the track.

Abstract: Bicycle crank comprising an elongated core with a first and a second end, a first and a second insert arranged on the ends of the core, and a high-resistance fiber coating incorporated in a plastic material matrix forming a casing incorporating the core and the inserts is provided. The core is a rigid element and each insert is equipped with a connecting portion inserted into a respective end of the core to establish a shape coupling therewith.

Abstract: A seal assembly includes a support, an outer seal extending circumferentially around a radially outer surface of the support, and an inner seal extending circumferentially around a radially inner surface of the support. In a more specific embodiment, the support comprises an annular base member, an inner ledge extending from a radially inner side of the base member, and an outer ledge extending from a radially outer side of the base member. The inner seal is disposed at a radially inner edge of the base member opposite the inner tubular member, and the outer seal is disposed around an outer peripheral surface of the outer tubular member.

Abstract: A bottom bracket assembly for a bicycle is comprised of a spindle and at least two cartridge bearings. The inner races of the cartridge bearings are axially fixed on the spindle by abutting stop elements. Crank arms attached to the ends of the spindle axially abut the outer stop elements, thus ensuring the precise and consistent axial location of the crank arms. Since the inner bearing races are fixed axially, the outer race of at least one cartridge bearing may be allowed to float in an axial direction to ensure proper alignment of the inner and outer races and the greatest possible bearing life for the bottom bracket.

Abstract: A crank arm (1) is provided that is connected to the crank head (2) through an elastic rotation axis (6) and a lock axis (7) having a reduced diameter (D) in the middle of said lock axis (7), the crank arm (1) also comprises a lock device (4) that is connected to the push button (5) and both together are easily moved down and upward with the user's thumb to release and lock the crank arm (1) between its operative and folded position, when the lock device (4) is pulled down a retaining spring (3) is compressed allowing the upper end of the lock axis (7) to flush with the crank arm hole (H) and releasing the crank arm (1) to rotate freely along its longitudinal plane with a 180° rotation angle in relation to the elastic rotation axis (6), by releasing the lock device (4) to its upper position it will lock the crank arm (1) at its folded position, then the fixation of the pedal-sprocket on the head crank (2) is performed by means of a fastening nut (5) which fix the crank head (2) to any commercially available p

Abstract: A bicycle crank arm apparatus includes an axle having a first end portion and a second end portion, wherein the first end portion has an outer peripheral surface and a threaded inner peripheral surface; an axle bolt having a threaded outer peripheral surface screwed into the threaded inner peripheral surface of the first end portion of the axle; a crank arm having an axle mounting boss defining an opening for receiving the first end portion of the axle therein, wherein the axle mounting boss includes a first fastener for tightening the crank arm mounting boss around the first end portion of the axle; and wherein the crank arm boss is positioned axially inwardly of the axle bolt.

Abstract: A bicycle with a triangulated crank structure replaces the single span crank arm which connects the spindle to the foot pedal on bicycles today. The triangulated crank structure is typically comprised of several sections including two linear spans of structural material arranged so that one end of each linear span connects with the other to form the vertex of an acute angle, proximate to a pedal attachment area. From the vertex, the linear spans diverge and each connects at its opposite end to separate locations on a structural element attached to an end of the bicycle's crankshaft or spindle.

Abstract: A bicycle pedal assembly includes a pedal and a cleat. The pedal includes a body that rotates about a shaft. Front and rear clamping member are coupled to opposite ends of the pedal body. Each of the clamping members has an engagement surface facing in a first direction. The cleat has front and rear attachment portions that are selectively engageable with the pedal via the front and rear clamping members. Specifically, the front and rear attachment portions have front and rear offset coupling surfaces engageable with the front and rear engagement surfaces. The pedal and the cleat are configured to form a rear float pivot axis on a rear side of a center rotation axis of the pedal and a front cleat release pivot axis on a front side of the center rotation axis.

Abstract: A crank includes a through hole defined in a first end thereof for receiving one of two ends of an axle in the bottom bracket, and a threaded hole defined in a second end of the crank so as to be connected with a pedal. A passage is defined through the crank and communicates with the through hole. A positioning assembly is received in the passage and includes two tubular members which are pulled toward each other by a bolt threadedly extending through the two tubular members. A concave surface is defined in each of the two tubular members so that the axle is pressed in position by the concave surfaces of the two tubular members.

Abstract: A quick release bicycle pedal mounting structure including a solid interchange plug connector connected to a crank and a female threaded manual connect coupling connected to a bicycle pedal. The quick release operates by manually pulling the spring (12) activated slide sleeve (9) on the connect coupling (3) perpendicular to the crank arm, which releases the ball bearings (11) into recesses within the connect coupling (3). Thereby allowing pedal (4) with attached connect coupling (3) to be easily detached from the plug connector (2), which is threaded into the crank arm (1).

Abstract: A pedal structure for exercise devices includes a pedal having a groove for receiving an operation rod therein and two positioning ports are defined in a side of the pedal. The positioning ports are continuous notches which are in communication with each other. Two connection ports are located on the operation rod and communicate with the positioning ports. Two positioning members respectively extend through the positioning ports and are engaged with the connection ports. The positioning members are able to slide between the continuous notches so as to adjust the effective length of the pedal relative to the operation rod.

Abstract: A drive mechanism for a bicycle transmission assist mechanism includes a crank arm having a drive member. The drive member includes a first abutment facing a forward rotational direction of the crank arm and a non-concave sloped surface facing a rearward rotational direction of the crank arm.

Abstract: A bicycle crank arm apparatus includes an axle having a first end portion and a second end portion, wherein the first end portion has an outer peripheral surface and a threaded inner peripheral surface; an axle bolt having a threaded outer peripheral surface screwed into the threaded inner peripheral surface of the first end portion of the axle; a crank arm having an axle mounting boss defining an opening for receiving the first end portion of the axle therein, wherein the axle mounting boss includes a first fastener for tightening the crank arm mounting boss around the first end portion of the axle; and wherein the crank arm boss is positioned axially inwardly of the axle bolt.

Abstract: A pedal drive mechanism that provides continuous, uninterrupted torque to the drive chain or belt. The continuous torque effect is a result of establishing two separate but connectively joined axes of rotation that transmit pedal crank force to the drive chain (55). The assembly of a right pedal crank (29) rotative mounted about left pedal output crank (28) are connectively fastened (46) to the left pedal crank (38) through the bottombracket bearing (37) defines the first axis of rotation. The assembly of the chain sprockets (35, 34 and 33), sprocket interface (25) and sprocket support (24) are rotatively mounted by a sealed bearing (40) about a bearing inner race support (23) and eccentric flange (22) establish a second axis of rotation. The fixtures of these two axes of rotation are connectively joined by articulating links (26) with self-aligning sealed bearings (27).

Abstract: An improved structure of a gear cluster for a bicycle having a crankset mounted with a crankshaft provided with a planetary gear module, wherein the planetary gear module includes a big wheel and a small wheel section and the planetary gear module drives an inner gear module mounted onto a gear plate, One lateral side of the crankshaft is provided with a driving structure including a second driving wheel and a third driving wheel engageable with the big and small wheels and the crankshaft is provided with a regulating structure for the positioning of the driving structure. The regulating structure includes two sets of a second and a third ratchet blocks for the positioning or free rotating of the second and the third driving wheels. The regulating structure is provided with a triggering structure to act on different ratchet block.

Abstract: A crank shaft assembly includes a socket, a crank shaft, two roller bearings, two mounting portions, two covers, and two steel ball sets. Thus, the roller bearings and the steel ball sets are arranged in different axial directions to bear the forces of two different directions. In addition, the roller bearings and the steel ball sets are arranged in different axial directions to increase the force bearing area of the crank shaft assembly, thereby preventing from producing stress concentration, so as to increase the lifetime of the crank shaft assembly.

Abstract: A crank structure includes a first combination block, a second combination block, a core layer, a resin layer, and an outer layer. Thus, the crank structure is formed by and entirely coated with the carbon fiber material without providing any metallic material, so that the crank structure has a light weight, thereby decreasing the whole weight. In addition, the crank structure is entirely coated with the carbon fiber material without forming any connection points, thereby enhancing strength and stiffness of the crank structure.

Abstract: A hollow bicycle crank arm has a central tubular portion to reduce weight and two mounting-boss portions for mounting a crank spindle and pedal during use. A crank arm base is forged or cast with a relatively thin back and sides, preferably out of aluminum or magnesium. The crank arm base has a generally C-shaped cross section. An arm cover has a top and sides and is made from stamped steel or titanium. The cover is placed over the open crank arm base to enclose a significant hollow section. The stamped arm cover does not require any threading or welding. It can be made using a very inexpensive stamping process. The crank arm can be made using relatively inexpensive traditional manufacturing processes such as die casting or forging.

Abstract: A bicycle crank includes a first connection portion with a first outer threaded portion and a second connection portion with a second outer threaded portion. A core portion made of carbon-fiber is connected between the first connection and the second connection portion. The first outer threaded portion and the second outer threaded portion are partially embraced by the core portion. An outer layer made of carbon-fiber is coated to the first connection portion, the second connection portion and the core portion.

Abstract: A human powered drive units each including a pair of a rotatable member having a sprocket and a supporting member having a sprocket, which are arranged up and down, and including a chain extended around the rotatable member and the supporting member, are disposed at left and right sides, respectively. The left and right rotatable members 1, 100 are fixed on a driving shaft 15. A chain ring 6 on which the load is applied is mounted on the driving shaft between upper rotatable member 1 and rotatable member 100. In each of the units, constraining means including a free crank (10 for the right-hand unit, and 1000 for the left-hand unit) and arm (11 for the right-hand unit, and 1100 for the left-hand unit), is provided so as to maintain perpendicularity of a shaft of the pedal relative to the plane in which the chain moves.