Abstract: A bicycle crank assembly is provided with a crank arm and an axial gap adjustment device. The crank arm has a crank axle mounting part, an extension part extending from the crank axle mounting part, a pedal attachment part provided on a radial outer end of the extension part and a sprocket attachment part. The axial gap adjustment device includes an adjustment adapter and an adjustment member. The adjustment adapter has a crank arm engagement structure that non-rotatably engages the crank arm, a first crank axle opening, and a first screw part. The adjustment member has a second crank axle opening, and a second screw part threadedly engaged with the first screw part to selectively position the adjustment member relative to the adjustment adapter.

Abstract: A crank system mounted to a drive sprocket of a bicycle includes a crank arm secured to the drive sprocket and disposed at both sides thereof, the crank arm having two bent ends; and two telescopic assemblies each comprising a bar having one end fixedly secured to either end of the crank arm, the bar having a cross section of polygon, the bar including a plurality of longitudinal notches, a sliding tube slidably put on the bar, the sliding tube including a surface opening communicating with the bar, and a pivotal lock member in the surface opening, the lock member being adapted to either dispose in one of the notches in a locked position of the telescopic assembly or clear the notch in a unlocked position of the telescopic assembly. This length adjustable bicycle crank system can save force when pedaling.

Abstract: A pedalling method and device for a user in standing position. The device includes a drive shaft whereof the rotation about its axis is coupled with the rotation of two right and left pedals. The pedals are mutually assembled via a plurality of cranks, connecting rods, and pivots such that: the pedals can travel freely along a circular path, for a constant rotational speed of the shaft, the speeds of the pedals are recurrent at equal time intervals but out of phase, minimal at lower dead center, maximal at upper dead center, and when the pedals are simultaneously at a common height lower than that of the center of the trajectory, the speeds of the pedals are equal. The vertical oscillation of the center of gravity of a user in standing position is reduced compared to a conventional pedal assembly.

Abstract: A bicycle crank assembly is provided that basically provided with a crank arm that includes a first outer shell, a second outer shell, a first axle supporting member and a second axle supporting member. The first outer shell has a first elongated portion with a first axle attachment end. The second outer shell has a second elongated portion with a second axle attachment end. The first and second outer shells are adhesively attached together to form an interior cavity therebetween. The first axle supporting member is disposed at the first axle attachment end of the first outer shell. The first axle supporting member has a first bore with a first splined inner surface that is at least partially disposed in the interior cavity between the first and second outer shells. The second axle supporting member is disposed at the second axle attachment end of the second outer shell.

Abstract: A bicycle gear crank that allows easy and proper circumferential position adjustment of the gear plate with respect to the crank arm. The bicycle gear crank includes a crank arm having a base end provided with a boss for mounting to a crank shaft an annular intermediate member non-rotatably around the boss 11a; a gear mount 3 which is supported non-rotatably fixed to the intermediate member, gear plates fixed around the gear mount, and a positional adjuster provided by spline fitting for changing relative circumferential position of the gear mount with respect to the intermediate member.

Abstract: A connecting and adjusting structure for a crank assembly used in a bicycle contains a first tube of a first connector including a first hollow portion, the first connector including a first bearing seat to receive a first ball bearing, the first bearing seat includes a first engaging tab, a first adjusting rib, and the first tube, a second connector including a second bearing seat to receive a second ball bearing, a dustproof cover, and a retaining ring, the second bearing seat including a second engaging tab, a second adjusting rib, and a second tube, a second crank including a central shank with plural T-shaped teeth and second internal screws, a first crank including a hollow post with a Tee groove fixed to engage with the T-shaped teeth, and a screw is inserted through the hollow post to be screwed with the second internal screws.

Abstract: A bottom bracket, which has a shaft, a first pedal crank, which is connected in a rotationally fixed manner to the shaft, a second pedal crank, which is connected in a rotationally fixed manner to the shaft, and a chainring carrier, which is connected to the shaft. The object of providing a bottom bracket with a chainring carrier that is easy to assemble is achieved by the chainring carrier being connected in a rotationally fixed manner to a chainring shaft and by the chainring shaft being connected in a rotationally fixed manner to the shaft.

Abstract: A transmission mechanism is used in a bicycle having a frame. The transmission mechanism includes a quick assembly device including a central shaft, threaded collars, and a clip bracket, which is adapted to mount to a lower frame portion of the bicycle frame and a multi-mode mechanism, which is supported and fixed by the quick assembly device to provide the bicycle with multiple modes of pedaling.

Abstract: A pedal propulsion system for a transportation conveyance comprises a pedal drive assembly having a teethed synchronous drive belt engaged between a drive sprocket and a transfer sprocket. The rotational axes of the transfer sprocket and the drive sprocket are oriented at an angle of up to 90 degrees from one another. The rotation of the transfer sprocket is conveyed to a propeller drive assembly mounted at the rear of a water craft by an elongated rotary shaft and a flexible transmission drive cable to facilitate removable of the propulsion system from the transportation conveyance.

Abstract: A crank set for a bicycle includes a crankshaft having a drive side shaft end part (3) and a non-drive side shaft end part (4), bearings (1, 2) for mounting the crankshaft rotatable in a bottom bracket shell of a frame of the bicycle, a drive side pedal crank (16), a non-drive side pedal crank (20), and at least one chain ring (14, 15) provided on the drive side shaft end part (3). The drive-side shaft end part (3) is provided with an integrally formed radially outwardly extending mounting body (7) upon which the drive side pedal crank (16) and the chain rings (14, 15) are mounted. The non-drive-side shaft part (4) may also be provided with an integrally formed radially outwardly extending mounting body (10) upon which the non-drive side pedal crank (20) is mounted.

Abstract: The present invention relates to a mechanical element, and more particularly, to a crank connected to a bicycle pedal or a handle for rotating a rotary body and to a bicycle using the same. The present invention uses a cylindrical cam, an end cam, or a swash plate cam, and the shafts of these cams and a shaft of a pedal or a handle for applying force are equipped with a miter gear (a bevel gear the number of teeth of which is 1:1 and the shaft angle of which is 90 degrees), such that the crank retracts/extends one time per one rotation of the pedal or the handle.

Abstract: A bicycle crank axle comprises an axle body having first and second end portions, a plurality of first splines disposed at the first end portion of the axle body, a plurality of second splines disposed at the second end portion of the axle body, and a projection extending radially outwardly from the first end portion of the axle body, wherein the projection is structured to abut against a lateral outer surface of a bicycle crank arm to prevent the bicycle crank arm from moving axially outward. A separate projecting member is mounted to the first end of the axle body to form the projection. The plurality of first splines extend radially outwardly from an outer peripheral surface of the axle body for engaging a splined surface of the bicycle crank arm, but the plurality of second splines do not extend radially outwardly relative to the outer peripheral surface of the axle body.

Abstract: A crank assembly for fitness equipment includes a ductile spacer engaged between a crankshaft mounting surface and a crank arm mounting surface at the interface thereof and conforming respectively to each to maximize surface contact area to distribute loads across a larger area.

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 bicycle chain wheel assembly is provided with a chain wheel and a chain wheel cover. The chain wheel has a central mounting portion and an outer gear with a plurality of outer gear teeth. The chain wheel cover is disposed on an exteriorly facing side of the chain wheel. The chain wheel cover has a mounting portion coupled to the chain wheel and an outer peripheral portion with a chain drop prevention protrusion projecting outwardly from the outer peripheral portion at a location that is radially inward of the outer gear teeth.

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.

Abstract: A driving mechanism for motorized bicycle is provided. The driving mechanism comprises a motor driving transmission device, a front driving sprocket and a pedal driving transmission device. The motor driving transmission device inwardly includes a motor shell, a magnet stator, an electromagnetic wire-coiled rotor and a cylindrical hollow rotatable shaft. The front driving sprocket has a transmission rotatable sleeve disposed therein for insertion of the hollow rotatable shaft there between. The pedal driving transmission device includes a pair of pedal cranks and a pedal driving shaft passing through the transmission rotatable sleeve and hollow rotatable shaft. First and Second single direction irreversible transmission devices are arranged such that either the motor driving transmission device or pedal driving transmission device may drive the transmission rotatable sleeve and front driving sprocket in proper rotational direction.

Abstract: A bicycle gear crank that allows easy and proper circumferential position adjustment of the gear plate with respect to the crank arm. The bicycle gear crank includes a crank arm having a base end provided with a boss for mounting to a crank shaft an annular intermediate member non-rotatably around the boss 11a; a gear mount 3 which is supported non-rotatably fixed to the intermediate member, gear plates fixed around the gear mount, and a positional adjuster provided by spline fitting for changing relative circumferential position of the gear mount with respect to the intermediate member.

Abstract: A bicycle chain wheel structure is configured with a right crank arm portion and an axle portion that are integrally formed together as a one-piece, unitary member. The right crank arm portion has an inner end integrally formed with the axle portion. The right crank arm portion has an outer end with a pedal mounting arrangement. The axle portion has a first end that is integrally formed with the right crank arm portion and a second end with a crank arm mounting arrangement. The axle portion has external threads disposed between the first and second ends of the axle portion. Thus, a portion of a bottom bracket is partially integrated into the bicycle chain wheel structure. Preferably, the chain guard is integrated into the right crank arm as a one-piece, unitary member. This arrangement reduces parts and manufacturing costs of the bicycle chain wheel structure.

Abstract: An improved multifunctional pedaling motion bicycle, particularly to a transmission mechanism of bicycle includes a clutch member that is manually controlled to move between and selectively engage primary and secondary control blocks to perform different modes of operation of the bicycle, including regular pedaling, independent pedaling of cranks, same-direction upward/downward movements of the cranks. The transmission mechanism has a simple and light-weighted structure and thus low cost and low failure risk with extended service life. Further, a variety of different operation modes can be performed without dedicated rear hub.

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 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 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 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 transmission mechanism is used in a bicycle having a frame. The transmission mechanism includes a quick assembly device including a central shaft, threaded collars, and a clip bracket, which is adapted to mount to a lower frame portion of the bicycle frame and a multi-mode mechanism, which is supported and fixed by the quick assembly device to provide the bicycle with multiple modes of pedaling.

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 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 crankset including a first crank and a second crank and a spindle. Each of the first crank and the second crank includes an end adapted to engage a pedal. The spindle includes a first end coupled to the first crank and a second end coupled to the second crank. The first end has an elongated portion secured to the first crank to define an elongated attachment between the first end and the first crank.

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 bicycle crank assembly has a right crank crimp-fastened to a crank shaft in such a manner that the external appearance is attractive. The crank shaft has a first and second portions with the second portion being positioned on the right side of the first portion and having a larger diameter than the first portion. The right crank has a sprocket mounting part, a right crank arm part, and an engagement bore formed in the center of the sprocket mounting part. The right crank is crimp-fastened to the crank shaft by installing the second portion of the crank shaft into the engagement bore and pressing the periphery of the engagement bore toward the outside in the axial direction of the crank shaft such that the pressed portion bulges radially inward and an annular space is formed between the crank shaft and the engagement bore.

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 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 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 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: 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 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: The present invention is a two-piece bicycle crank set comprising of two monolithic, thin-wall continuous tubular members. Each tubular member includes a crank arm and a one-half portion of a crank axle, where the crank arm and the portion of the crank axle form a continuous thin-wall tubular shape. The two tubular members are coupled precisely midway between two bearing sets within a bracket shell of a bicycle. The coupling connecting the two tubular members can include an outer sleeve, an inner sleeve, two exteriorly tapered and internally threaded bushings and a threaded stud. Turning the threaded stud positions the bushings to expand the inner sleeve, whereby the crank axle portions of the two tubular members are secured within the inner sleeve and the outer sleeve by the expanding inner sleeve. Alternatively, an interference fit coupling connects the two tubular members, and includes a mortise member and a tenon member.

Abstract: A pedal crank drive for a bicycle is described with two pedal cranks (2) which are torsionally rigidly connected with each other via a bottom bracket axle (1), comprising a chainwheel (3) which is held in a rotatable manner and is limited on a stop on a bearing nose (5) of one of the two pedal cranks (2) and at least one compression spring (12) extending in the circumferential direction between said pedal crank (2) and the chainwheel (3) bearing an abutment (14) for the compression spring (12). In order to provide advantageous constructional conditions it is proposed that the pedal crank (2) carrying the chainwheel (3) engages with a nose (16) which projects against the chainwheel (3) in a recess (17) of the chainwheel (3) which forms rotation limit stops (18, 19) for said pedal crank (2) in both circumferential directions.

Abstract: A bicycle transmission has a plurality of cone gears with multiple gear surfaces and a corresponding plurality of ratio-change assemblies for selecting one of the gear surfaces of each cone gear. One cone gear provides reductions of the input rotary speed while the other cone gears provide increases in the input rotary speed. The ratio-change assemblies include apparatus for moving its gear surface both vertically and horizontally. The transmission includes a telescopic pedal arm assembly for input power and torque. The telescopic pedal arm is driven between an extended position and a retracted position during each revolution so that the available torque increases in conjunction with available leg power.

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 axle 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 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 planetary sphere/ring gear, comprising a sphere and a ring, which are interconnected by a ball and a socket. The ball is located on the edge of a circular opening in the ring and the socket is located on the body of the sphere. Used in conjunction with this planetary sphere/ring gear is a pedal-powered three or more wheeled vehicle which comprises a chain wheel, and pedals which swivel and which swing on a cradle. An operator's seat also swings on said cradle. Even though traversing across slopes, the chain wheel, pedals and seat are in a straight-with-the-world position, which is a natural and comfortable position for pedaling. The planetary sphere/ring gear is needed in the vehicle to allow the toothed ring, with a drive chain around it, to change its axis to line up with the drive wheel, as it swivels and swings.

Abstract: The crank arm quick release device of a bicycle includes a fixing threaded sleeve screwed on the rotation shaft of the pedal, and a crank arm formed with locking recesses for locking and fixing the fixing threaded sleeve. Thus, the pedal may be mounted on the crank arm easily and quickly.

Abstract: A quick change chain ring arrangement for use on a bicycle crank assembly includes a chain ring adapter that is connected to and rotates with the crank assembly about the crank assembly rotational axis. A removable chain ring support removably engages with the chain ring adapter. The chain ring support has a minimum inside opening formed into the chain ring support that is larger than the maximum cross sectional area perpendicular to the longitudinal axis of the crank arms thereby allowing the chain ring support to be installed onto and removed from the crank assembly without requiring the removal of the crank arms or pedals from the crank assembly and without requiring the removal of the crank assembly from the bicycle frame.

Abstract: A power-saving driving device for treading the pedals of a bicycle is disclosed. Thereby, the driver may use a smaller force to tread a bicycle so that a higher efficiency is provided. The power-saving device comprises two crank axles. The two crank axles are fixed to a gear box. Two spur gears are engaged to the gear box, and two free wheels are installed at an exterior of the gear box. The two spur gears and two free wheels are connected to the two crank axles. The two free wheels are connected through a chain; and a chain wheel and a bearing are connected to the crank axles. Thereby, the forces from the right and left legs can be outputted effectively. The driving of a bicycle and the power necessary are improved. Therefore, the driver treads the pedals with a smaller depth and thus the physical consumption is reduced.

Abstract: The unit comprises two variable-length pedal cranks (20) having a common rotation pin (21) of transverse axis (A), and a mechanism (34, 35, 36) for varying the length of the two pedal cranks (20) on the basis of their angular position; the position of the axes of the pedals (25) in the vertical plane of projection defines, as the angular position of the pedal cranks (20) varies, an endless closed curve (F) about a reference axis (R) which is displaced by an angle of about 15 degrees forwards from the axis (N) passing through the center of the seat (11) of the bicycle and intersecting the axis (A) of the pin (21).