CA2414681A1 - Oscillating step drive for a bicycle - Google Patents
Oscillating step drive for a bicycle Download PDFInfo
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- CA2414681A1 CA2414681A1 CA002414681A CA2414681A CA2414681A1 CA 2414681 A1 CA2414681 A1 CA 2414681A1 CA 002414681 A CA002414681 A CA 002414681A CA 2414681 A CA2414681 A CA 2414681A CA 2414681 A1 CA2414681 A1 CA 2414681A1
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- bicycle
- pedal
- pulley
- cable
- drive mechanism
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
- B62M1/00—Rider propulsion of wheeled vehicles
- B62M1/24—Rider propulsion of wheeled vehicles with reciprocating levers, e.g. foot levers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K3/00—Bicycles
- B62K3/002—Bicycles without a seat, i.e. the rider operating the vehicle in a standing position, e.g. non-motorized scooters; non-motorized scooters with skis or runners
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Steering Devices For Bicycles And Motorcycles (AREA)
Abstract
A quasi-rectilinear drive mechanism for a bicycle comprised of left and right crank arm and pedal assemblies, each of said crank arms driving a transverse crankshaft through left and right one-way clutch assemblies. The rider applies alternate pedal strokes to the crank arms, thereby inducing unidirectional forward rotation of said crankshaft and associated power transmission components too the rear wheel. To provide support for a standing rider during coasting as well as forcing synchronized, opposed pedal strokes, each crank arm is constrained to rotate within its forward quadrant by means of a cable and pulley. Said pulley is affixed by a swivel mount near the bicycle's steering head at an approximately 45-degree angle above the crankshaft's axis of rotation.
A cable passing over said pulley is affixed at each end to one of the two pedals, thereby causing each pedal to lift its opposite-side crank assembly as it is depressed. The cable's length and pulley's location are configured such that cable tension provides a positive pedal stop at the top and bottom of each stroke. Embodiments may be retrofitted to conventional bicycles or incorporated into miniature step scooters.
A cable passing over said pulley is affixed at each end to one of the two pedals, thereby causing each pedal to lift its opposite-side crank assembly as it is depressed. The cable's length and pulley's location are configured such that cable tension provides a positive pedal stop at the top and bottom of each stroke. Embodiments may be retrofitted to conventional bicycles or incorporated into miniature step scooters.
Description
BACKGROUND
A significant drawback of conventional bicycle propulsion systems is the non-linear power output inherent to their rotating pedal cranks. Rider ergonomics dictate that optimal energy transfer from the leg muscles to the rear wheel occurs when the crank arms are in the forward horizontal position (point of maximum leverage). Power transfer varies as a sine wave such that when either crank arm is pointed straight up or straight down (worst case position), any downward force onto the pedals provides no propulsive force whatsoever. Only the forward pedaling quadrant produces significant power, therefore rotational foot motion causes the rider's feet to travel twice as far per power stroke than if foot motion were linear.
The lack of constant power output from a rotating crank drive is particularly problematic when attempting to pedal a high gear ratio up a hill: the vehicle will tend to stall as the sinusoidal power output crosses zero. Furthermore, the seated position of a conventional bicycle is ergonomically sub-optimal. It's a more ergonomically efficient posture for the rider to stand over tlsr pedals while applying a stepping ~tion that raises and applies their entire body weight onto each pedal in succession. If the overall gear ratio is sufficiently high, after each step up, the rider can rest straight-legged while gravity provides an even power output until the pedal has descended to its lower end of travel whereupon another burst of energy from the strong leg muscles is applied to step up onto the opposite pedal.
Attempts have been made to overcome the problems inherent to a rotating crank by devising various linear drive mechanisms that maintain good force geometry throughout the rider's leg stroke (i.e. ones that provide a vertical "stair-stepping" motion rather than a circular pedaling motion). Shelley (US 3.891,235), Zampedro (US
4,169,609) and Megurditchian (LTS 5,236,211) all propose rectilinear drive mechanisms for use by seated riders. However, each of these mechanisms is overly complex, requiring a wide variety of brackets, rectilinear pedal guides, chains, pulleys and clutches.
The weight and friction of their devices detract from the potential efficiency gains of rectilinear pedal motion.
Other attempts at improving drive train efficiency utilize a quasi-linear pedal actuation to simplify the mechanism. Titcomb (US 4,379,566) Parker (GB
A significant drawback of conventional bicycle propulsion systems is the non-linear power output inherent to their rotating pedal cranks. Rider ergonomics dictate that optimal energy transfer from the leg muscles to the rear wheel occurs when the crank arms are in the forward horizontal position (point of maximum leverage). Power transfer varies as a sine wave such that when either crank arm is pointed straight up or straight down (worst case position), any downward force onto the pedals provides no propulsive force whatsoever. Only the forward pedaling quadrant produces significant power, therefore rotational foot motion causes the rider's feet to travel twice as far per power stroke than if foot motion were linear.
The lack of constant power output from a rotating crank drive is particularly problematic when attempting to pedal a high gear ratio up a hill: the vehicle will tend to stall as the sinusoidal power output crosses zero. Furthermore, the seated position of a conventional bicycle is ergonomically sub-optimal. It's a more ergonomically efficient posture for the rider to stand over tlsr pedals while applying a stepping ~tion that raises and applies their entire body weight onto each pedal in succession. If the overall gear ratio is sufficiently high, after each step up, the rider can rest straight-legged while gravity provides an even power output until the pedal has descended to its lower end of travel whereupon another burst of energy from the strong leg muscles is applied to step up onto the opposite pedal.
Attempts have been made to overcome the problems inherent to a rotating crank by devising various linear drive mechanisms that maintain good force geometry throughout the rider's leg stroke (i.e. ones that provide a vertical "stair-stepping" motion rather than a circular pedaling motion). Shelley (US 3.891,235), Zampedro (US
4,169,609) and Megurditchian (LTS 5,236,211) all propose rectilinear drive mechanisms for use by seated riders. However, each of these mechanisms is overly complex, requiring a wide variety of brackets, rectilinear pedal guides, chains, pulleys and clutches.
The weight and friction of their devices detract from the potential efficiency gains of rectilinear pedal motion.
Other attempts at improving drive train efficiency utilize a quasi-linear pedal actuation to simplify the mechanism. Titcomb (US 4,379,566) Parker (GB
2,044194) and Mohseni (US 5,520,401) utilize conventional pedal cranks that oscillate along curved paths that approximate rectilinear pedal motion which in turn transfers power to the real wheel using various cable a~ capstan configurations. Their mechanisms are somewhat more efficient and also exploit the ergonomic advantage of a standing rider.
However these cable driven designs require the fabrication of many non-standard bicycle parts and are not generally compatible with existing bicycles. Their component geometry also renders them difficult to miniaturize sufficiently for carrying onto mass transit vehicles.
Proia (US 5,390,773) and Day (US 5,860,329) propose mechanisms that utilize independent one-way clutches at each end of the bicycle's crankshaft. A
skillful rider may utilize these one-way clutches to maintain each crank arm within its forward quadrant during pedaling. This general configuration permits quasi-rectilinear (curved) pedal motion with minimal component changes to a conventional bicycle. Day's mechanism lacks any means for synchronizing the pedals nor a means for raising them within the forward quadrant. It is therefore impractical for general transportation and only suftable for use as a training aid for athletes equipped with cleated bicycle shoes (weak leg muscles are trained to maintain tangential pedaling force throughout the crank's revolution).
To address this problem, Proia's drive mechanism utilizes springs attached to each crank arm that return the crank to the top its stmke, however the need to repeatedly stretch these springs adds considerable overall friction to the drive mechanism.
Furthermore, since the crank arms operate independent of each other and no positive stop is provided at the bottom of each stroke, the rider is forced to remain seated while coasting (otherwise both crank arms would rotate down to hang vertically).
It is therefore an object of the present invention to provide a simple, quasi-rectilinear step drive mechanism for a bicycle that forces synchronous and opposing crank oscillations within the forward quadrant of possible pedal motion. It is a further objective to provide a step drive wherein the force applied to one pedal directly raises the opposite pedal. It is a further objective to provide a step drive with few moving parts and one that is adaptable for fitting to existing bicycles. It is a further objective to provide a step drive that permits the rider to coast while standing on both pedals with both crank arms horizontal. It is a further objective to provide a step drive and associated bicycle components compact enough to be easily brought onboard mass transit vehicles.
Further objectives and advantages of the invention will become apparent from consideration of the ensuing description and drawings.
SUMMARY OF THE INVENTION
The present invention provides a drive mechanism for a bicycle, which overcomes the problems noted in previous linear and quasi-linear drive mechanisms. The invention includes a crankshaft mounted transversely on the bicycle, a rotary drive element affixed to the crankshaft and coupled for transfer of power to the rear wheel by an endless, flexible drive element; a pair of crank arm and rotateable pedal assemblies, each coupled to an end of the crankshaft via a one-way clutch which constrains rotation of the crankshaft to towards the front of the bicycle; a pulley, flexibly affixed to the frame of the bicycle and located at a point forward and above the crankshaft; a length of cable passed over said pulley and affixed at its ends to the deft and right pedals respectively, said cable length and pulley location being configured such that when a crank arm and pedal assembly is raised to the location where pedal to pulley distance is minimized, cable tension arrests the opposite crank arm and pedal assembly at the bottom of its desired quadrant of motion.
In one embodiment, the drive mechanism is configured as a kit for converting a standard, full-sized bicycle. This kit comprises replacement crank assembly components including left and right one-way clutches that permit each crank arm to operate independemly and impart only forward rotation to the crank, a pulley and pulley hanging bracket that permits said pulley to be flexibly affixed to the bicycle frame and a cable passed over the cable and affixed at each end to a pedal using means that minimize stresses within the crank assembly. A replacement seat post and handlebar may also be provided for moving the seat up and forward to a location more ergonomically suitable for the stair-stepper pedaling motion.
In another embodiment, the drive components are incorporated into rnewly manufactured bicycles.
In another embodiment, a seatless mid-sized bicycle is comprised of the sic crank and pulley drive configuration described above together with a folding handlebar that reduces the volume of the vehicle when stored and that also serves as a storage stand when the vehicle is tipped backwards over its rear wheel.
In another embodiment, a miniature spar-frame is disclosed that renders the step-driven vehicle compact enough to be easily carried onto mass transit vehicles.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an oblique view of the step drive mounted to a full sized conventional bicycle.
FIG. 2 is an oblique view of the step drive mounted to a small bicycle without a seat.
FIG. 3 is an oblique view of the step drive mounted to a miniature step scooter fray.
FIG. 4 is an exploded view showing one embodiment of a suitable one-way clutch FIG. 5 is an exploded view showing another embodiment of a suitable one-way clutch FIG. 6 is an oblique version of the step driven bicycle of FIG 2, further configured with a fairing to compensate for wind drag on the standing rider.
FIG 7 is a large-scale view onto the embodiment shown in FIG 2, showing details of an alternate means for arresting pedal motion within the forward quadrant.
FIG 8 is a side view of the embodiment shown in FIG 1 showing a modified seat post that displaces the seat to a more ergonomically correct position with respect to the pedals.
However these cable driven designs require the fabrication of many non-standard bicycle parts and are not generally compatible with existing bicycles. Their component geometry also renders them difficult to miniaturize sufficiently for carrying onto mass transit vehicles.
Proia (US 5,390,773) and Day (US 5,860,329) propose mechanisms that utilize independent one-way clutches at each end of the bicycle's crankshaft. A
skillful rider may utilize these one-way clutches to maintain each crank arm within its forward quadrant during pedaling. This general configuration permits quasi-rectilinear (curved) pedal motion with minimal component changes to a conventional bicycle. Day's mechanism lacks any means for synchronizing the pedals nor a means for raising them within the forward quadrant. It is therefore impractical for general transportation and only suftable for use as a training aid for athletes equipped with cleated bicycle shoes (weak leg muscles are trained to maintain tangential pedaling force throughout the crank's revolution).
To address this problem, Proia's drive mechanism utilizes springs attached to each crank arm that return the crank to the top its stmke, however the need to repeatedly stretch these springs adds considerable overall friction to the drive mechanism.
Furthermore, since the crank arms operate independent of each other and no positive stop is provided at the bottom of each stroke, the rider is forced to remain seated while coasting (otherwise both crank arms would rotate down to hang vertically).
It is therefore an object of the present invention to provide a simple, quasi-rectilinear step drive mechanism for a bicycle that forces synchronous and opposing crank oscillations within the forward quadrant of possible pedal motion. It is a further objective to provide a step drive wherein the force applied to one pedal directly raises the opposite pedal. It is a further objective to provide a step drive with few moving parts and one that is adaptable for fitting to existing bicycles. It is a further objective to provide a step drive that permits the rider to coast while standing on both pedals with both crank arms horizontal. It is a further objective to provide a step drive and associated bicycle components compact enough to be easily brought onboard mass transit vehicles.
Further objectives and advantages of the invention will become apparent from consideration of the ensuing description and drawings.
SUMMARY OF THE INVENTION
The present invention provides a drive mechanism for a bicycle, which overcomes the problems noted in previous linear and quasi-linear drive mechanisms. The invention includes a crankshaft mounted transversely on the bicycle, a rotary drive element affixed to the crankshaft and coupled for transfer of power to the rear wheel by an endless, flexible drive element; a pair of crank arm and rotateable pedal assemblies, each coupled to an end of the crankshaft via a one-way clutch which constrains rotation of the crankshaft to towards the front of the bicycle; a pulley, flexibly affixed to the frame of the bicycle and located at a point forward and above the crankshaft; a length of cable passed over said pulley and affixed at its ends to the deft and right pedals respectively, said cable length and pulley location being configured such that when a crank arm and pedal assembly is raised to the location where pedal to pulley distance is minimized, cable tension arrests the opposite crank arm and pedal assembly at the bottom of its desired quadrant of motion.
In one embodiment, the drive mechanism is configured as a kit for converting a standard, full-sized bicycle. This kit comprises replacement crank assembly components including left and right one-way clutches that permit each crank arm to operate independemly and impart only forward rotation to the crank, a pulley and pulley hanging bracket that permits said pulley to be flexibly affixed to the bicycle frame and a cable passed over the cable and affixed at each end to a pedal using means that minimize stresses within the crank assembly. A replacement seat post and handlebar may also be provided for moving the seat up and forward to a location more ergonomically suitable for the stair-stepper pedaling motion.
In another embodiment, the drive components are incorporated into rnewly manufactured bicycles.
In another embodiment, a seatless mid-sized bicycle is comprised of the sic crank and pulley drive configuration described above together with a folding handlebar that reduces the volume of the vehicle when stored and that also serves as a storage stand when the vehicle is tipped backwards over its rear wheel.
In another embodiment, a miniature spar-frame is disclosed that renders the step-driven vehicle compact enough to be easily carried onto mass transit vehicles.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an oblique view of the step drive mounted to a full sized conventional bicycle.
FIG. 2 is an oblique view of the step drive mounted to a small bicycle without a seat.
FIG. 3 is an oblique view of the step drive mounted to a miniature step scooter fray.
FIG. 4 is an exploded view showing one embodiment of a suitable one-way clutch FIG. 5 is an exploded view showing another embodiment of a suitable one-way clutch FIG. 6 is an oblique version of the step driven bicycle of FIG 2, further configured with a fairing to compensate for wind drag on the standing rider.
FIG 7 is a large-scale view onto the embodiment shown in FIG 2, showing details of an alternate means for arresting pedal motion within the forward quadrant.
FIG 8 is a side view of the embodiment shown in FIG 1 showing a modified seat post that displaces the seat to a more ergonomically correct position with respect to the pedals.
3 DETAILED DESCRIPTION
FIG. 1 illustrates conventional, full sized bicycle 1 that has been modified by fitting the present invention. Bicycle 1 is comprised of top tube 28 joined to head tube 27, joined to down tube 30, joined to bottom bracket tube 31 joined to seat tube 29 joined to top tube 28. Head tube 27 houses handlebars 21 steering front fork 25 and front wheel 2. Affixed rear fork 26 carries rear wheel 3 for propulsion of the bicycle.
Seat 4 is affixed to bicycle 1 via adjustable seat post 32 and the seated rider alternatively presses down onto pedals 7 and 8, to impart oscillating motion to crank arms 10, 11 and forward rotational motion to front sprocket 9. Endless belt 6 is a flexible chain (not fully illustrated) that engages both front sprocket 9 and rear sprocket 5, thereby transmitting the forward rotation of sprocket 9 to rear wheel 3. Endless belt 6 is typically a standard bicycle chain however a dry, toothed belt (not illustrated) may also be employed to reduce weight and improve cleanliness. Rear hub 29 may include internal planetary gears for varying the overall ratio of the step-drive transmission. A derailleur gear changing system (not illustrated) may also be employed.
In a conventional bicycle, the crank arms are perma~ntly fixed at 180 degrees out of phase (not illustrated). The present invention permits independent relative motion of crank arms 10 and 11 by means of one-way clutches 12 and 13, which automatically disengages each crank arm from the drive mechanism while rotating counterclockwise and re-engages each crank arm to the drive mechanism while rotating clockwise (see FIG
FIG. 1 illustrates conventional, full sized bicycle 1 that has been modified by fitting the present invention. Bicycle 1 is comprised of top tube 28 joined to head tube 27, joined to down tube 30, joined to bottom bracket tube 31 joined to seat tube 29 joined to top tube 28. Head tube 27 houses handlebars 21 steering front fork 25 and front wheel 2. Affixed rear fork 26 carries rear wheel 3 for propulsion of the bicycle.
Seat 4 is affixed to bicycle 1 via adjustable seat post 32 and the seated rider alternatively presses down onto pedals 7 and 8, to impart oscillating motion to crank arms 10, 11 and forward rotational motion to front sprocket 9. Endless belt 6 is a flexible chain (not fully illustrated) that engages both front sprocket 9 and rear sprocket 5, thereby transmitting the forward rotation of sprocket 9 to rear wheel 3. Endless belt 6 is typically a standard bicycle chain however a dry, toothed belt (not illustrated) may also be employed to reduce weight and improve cleanliness. Rear hub 29 may include internal planetary gears for varying the overall ratio of the step-drive transmission. A derailleur gear changing system (not illustrated) may also be employed.
In a conventional bicycle, the crank arms are perma~ntly fixed at 180 degrees out of phase (not illustrated). The present invention permits independent relative motion of crank arms 10 and 11 by means of one-way clutches 12 and 13, which automatically disengages each crank arm from the drive mechanism while rotating counterclockwise and re-engages each crank arm to the drive mechanism while rotating clockwise (see FIG
4 and FIG 5 for details of one-way clutches).
Crank arms 10 and 11 are constrained to operate within the front quadrant of possible motion by means of cable 16 and pulley 17. Efficient force geometry is mairnained when each crank arm operated within a range of approximately +/- 45 degrees from the horizontal (see FIG 8 for an orthogonal illustration of typical crank motion range).
Cable 16 is typically a mufti-strand steel cable. Pulley 17 is a conventional pulley assembly comprised of a disk grooved around its circumference to receive cable 16 and rotateably affixed within a supporting shell having an upper swivel or loop for suspending the assembly. Pulley hanger 18 is a tube clamp assembly having a U
shaped loop projecting from its lower surface, thereby providing means for suspending pulley 17.
The pulley hanger shown is a two-piece clamp screwed together however other clamping brackets will be obvious to those practiced in the art. For example: a "hose clamp" or "C
clamp" type of pulley hanger are within the scope of the invention. When the engagement loop portion of pulley 17 is loosely engaged through the engagement loop portion of pulley hanger 18, the orientation of pulley 17 can swivel freely within a certain range, thereby permitting cable 16 to track smoothly into the pulley's groove as the cable's orientation changes in response to pedal motion.
Cable 16 passes over pulley 17 and affixes to right pedal 7 and left pedal 8.
The rider steps alternately on pedals 7 and 8 to impart forward rotation to front sprocket 9, chain 6, rear sprocket 5 and rear wheel 3. When the length of cable 16 and the location of pulley 17 are configured as illustrated in FIG 1 and FIG 3:
1 ) Depressing either pedal will simultaneously cause the opposite pedal to rise, thereby permitting the rider to oscillate both crank arms within the forward quadrant using a stepping motion.
2) By applying equal foot pressure, the rider can coast comfortably while standing on both pedals suspended at the same height.
3) The descending crank arm is arrested at the bottom of its desired motion quadrant when no more cable slack is available for further lifting of the ascending crank. This permits the lowered pedal to bear the entire weight of the rider while the opposite leg is freed for other activities such as push starting the vehicle from a stop or to actuating a foot operated rear brake (see FIG. 3).
Cable 1 b is affixed at one end to rotateable pedal 8 and at the other end to rotateable pedal 7. Pedals 7,8 may be either a conventional bicycle pedal threaded flush through the crank arm (not illustrated). Alternatively, each pedal's axle may be extended through the crank arm as shown by axle extensions 14, 15.
Referring to FIG 3, it is evident that due to the short distance between pulley 17 and raised pedal 8, if cable 16 were attached directly to the pedal, very considerable lateral bending forces would be generated in crank arm 11 and one-way clutch 13 when the rider's full weight is applied to pedal 7. Therefore, pedal axle extensions 14 and 15 are provided to bring the pedal's attachment point closer to the centerline of bicycle 1, thereby reducing and balancing stresses within the drive train components.
Referring back to FIG 1, even when pedal 8 is fully raised, the larger "adult sized" bicycle frame leaves a large distance between the raised pedal and pulley 17, thereby causing cable 16 to be more inline with crank arm 11. Given this nearly linear cable-to-crank arm geometry, pedal axle extensions 14 and 15 may be shortened or omitted when fitting the invention to large sized bicycle frames.
Another means for reducing excessive lateral forces onto the crank arms is to increase the diameter of pulley 17 beyond that shown in the drawings. A well-implemented embodiment of the invention will minimize stresses by using a balanced combination of the frame size, the length of pedal axle extensions 14, 15, the diameter of pulley 17 and the rigidity of the transmission the components such as bearings, crank arms, pivots etc.
A suitable cable-to-pedal fixation means is to form a loop at each cable end (not illustrated). Each loop passes around a bicycle pedal's axle such that the loop is captured in tire groove between the pedal's rotateable portion and the outer side of the crank arm (not illustrated). The cable loop size may adjustable, thereby permitting the rider to adjust the length of cable 16, which in turn adjusts the lower limit of pedal travel. A bolt threaded into the inboard end of the pedal axle might also be used to secure a suitably terminated cable end to the pedal/crank assembly (not illustrated). To minimize friction, the cable fixation should be loose enough to pivot in response to angular changes to tensioned cable 16.
Similar fixation means may be employed for affixing the cable ends to the inner ends of pedal extensions 14,15 when such extensions are required for fitting the invention tv smaller bicycle frames. FIG 5 illustrates another suitable fixation means:
cable ends 52 fit into slots 53 farmed in the ends of pedal extensions 14 and 15. A
recess formed in the underside of each slot 53 engages cable end 52 to secure it in place.
Other cable fixation means will be obvious to those practiced in the art.
Referring now to FIG 8: modified seat post 32 may be provided that compensates for the more forward rider position necessitated by pedal motion being restricted to the forward quadrant. Seat post 32 telescopes within seat tube 29 in tl~ same manner as the stock (strait) version to provide vertical seat adjustment. Modified seat post 32 includes a horizontal portion that displaces the fixation point of seat 4 towards tl~
front of bicycle 1.
The rider can thereby slide and clamp the seat forward at a location where their center of gravity is centered over pedals 7 and 8. Typical riders will also raise the seat somewhat to compensate for the pedals not descending as low as on a stock bicycle.
Handlebar 21 may also be modified to move the rider's hands somewhat up and forward (not illustrated).
FIG 2 illustrates a smaller "children's sized" bicycle frame adapted and fitted to an embodiment of the present invention. A standing adult rider would be too tall to make use of a seat, therefore the seat is omitted to save weight a~ provide for a ~re compact assembly when stored. Handlebar 21 is adjustable in height by means of telescopic tube 20 and suitable clamping fixture (not illustrated). To further reduce the vehicle's overall height, telescopic tube 20 is hinged to head tube 27 by means of hinge joint 19 having a suitable friction clamping means for fixing telescopic tube 20 at the desired angle. To facilitate storage, handlebar 21 is collapsed into telescopic tube 20 and hinge joint 19 is loosened whereupon the entire handlebar assembly is folded down towards rear wheel 3.
To minimize the bicycles storage footprint and also prevent the parked vehicle from falling over, front wheel 2 may be raised backwards past rear wheel 3 while the angle and extension of handlebar 21 is adjusted such that rear wheel 3, and the left and right bar ends 22 form a support triangle on the ground (not illustrated).
Handlebar 21 may be a hinged T as illustrated however other collapsible or folding handlebar configurations are also within the scope of the invention.
High-rise "cow horn" style handlebars affixed by a conventional handlebar clamp may also be loosened and then folded rearward. Collapsible T style bars that have removable left and right handgcips may also be used. To reduce the overall width of the bicycle during storage, pedals 7 and 8 may be foldable. Such foldable pedals are commercially available (e.g.: Wellgo model FP-3 or MKS model FD2).
An alternate means of arresting pedal motion within the forward quadrant is sometimes useful when frame geometry forces pulley holder 18 to be ai~xed at too high an angle. FIG 2 illustrates pulley 17 and pulley holder 18 mounted only slightly forward of the rotational axis of crank arms 10 and 11, thereby causing the crank's upper limit of motion to be near vertical. Therefore, means are provided to constrain pedal motion within the desired +/- 45 degrees from horizontal. Pedal stop 23 is a tube clamp fixture similar to pulley holder 18 that is affixed to down tube 30 at a location where it obstructs pedal extensions 14 and 15 from rising higher than is consistent with good quasi-linear pedaling efficiency. Notch 33 is formed in pedal stop 23 such that it blocks pedal axle extensions 14, 15 while permitting cable 16 to run freely towards pulley 17 (see FIG 7 for clearer detail).
A truly miniature embodiment of the invention suitable for carrying onto mass transit vehicles requires a specially constructed frame arid associated components.
Referring to FIG 3: spar frame 48 replaces the triangulated tube frames used in previously described embodiments. Spar frame 48 may be a length of rectangular section aluminum tubing having rear cutouts on its upper and lower surface that receive rear wheel 3 to form rear fork 26. Head tube 26 is typically welded to the front end of spar frame 48 and may include strengthening gusset 49.
Head tube 26 may be shaped to provide a handhold for conveniently carrying the folded bicycle. If strengthening gusset 49 is included, its rear edge may also be rounded as shown to provide a comfortable handl~ld that is closer to rear wheel 3 than head tube 26. The rounded handhold facilitates transport of the folded bicycle while being earned straight-armed (like a briefcase) without having the vehicle's rear wheel hitting the ground. A shoulder strap may also be provided that engages onto either head tube 27 or strengthening gusset 49, thereby permitting the rider to sling the folded bicycle their arm for convenient carrying. To facilitate carrying in this manner, handlebar 21 and pedals 7, 8 may include folding or collapsible means as previously described.
To reduce weight, front fork 25 may include only a single leg as shown or may be configured conventionally with two legs as illustrated in FIG 1 and FIG 2. The step drive mechanism for this embodiment is comprised of the same components and configuration as that used in the medium and large sized embodiments described above.
Bottom bracket tube 31 is welded to the top of spar frame 48 for housing the crankshaft and one-way clutches 12, 13 (detailed below). Spmckets 9 and 5 are engaged to either an endless chain or an endless belt (neither illustrated). The diameter of rear wheel 3, rear sprocket 5 and front sprocket 9 may be made larger or smaller as necessary in order to achieve the gear ratio appropriate to the power delivery characteristics of the step drive mechanism.
A conventional hand-operated caliper brake may be employed for stopping the vehicle (not illustrated). To reduce weight a~xi simplify construction, foot operated brake 34 may be provided. Foot brake 34 is a rigid or semi-rigid strap of metal or similar material. Foot brake 34 is secured to spar frame 48 and/or bottom bracket tube 31 such that it cantilevers backwards, closely above rear wheel 3. When the rider wishes to stop, foot pressure is applied onto the top of foot brake 34, thereby bending the resilient strap down into braking contact with rotating rear wheel 3. Actuation of the brake may be either by flexion of a resilient strap at~xed as described above or by means of a hinge and return spring fixation between the brake the spar frame (not illustrated).
FIG 4 is an exploded view of the one-way clutches 12, 13 used to transform quasi-linear pedal motion into rotation of rear wheel 3. These particular left and right clutches are standard off the-shelf indexing roller clutches such as the Torrington FCB-30 or the Stieber NFR-35. Such clutches are comprised of left and right outer bearing hubs 41, 42 coupled to left and right inner bearing hubs 37, 38 via left and right roller clutches 39, 40. Roller clutches 39 and 40 utilize tiny internal ramps and springs that bias a plurality of rollers such that they jam between the inner and outer hubs when rolled in one direction yet act as an anti-friction bearing when rolled in the opposite direction.
Right pedal 7 rotates crank arm 10, which in turn drives outer bearing hub 42.
When hub 42 rotates clockwise, roller clutch 40 jams against inner hub 38, thereby causing sprocket carrier 36 and sprocket 9 to rotate clockwise with attendant forward propulsion of the rear wheel. Sprocket 9 and sprocket carrier 36 may be formed as a single monolith however the use of two discrete components permits sprocket 9 to be a standard off the-shelf bicycle component. While pedal 7 is being lifted by cable 16, outer bearing hub rotates counterclockwise with respect to inner hub 38 therefore roller clutch 40 disengages power transmission from the rear wheel.
While coasting with no pedal movement, forward rotation of wheel 3 causes forward rotation of rear sprocket 5, chain (or toothed belt) 6, front sprocket 9, sprocket carrier 36 and inter hub 38. Roller clutch 40 will however decouple inner hub 38 from outer hub 42, thereby enabling the pedals to remain stationary while at the same time eliminating the need for the stacxlard bicycle freewheel normally located between rear hub 24 and sprocket S.
Crankshaft 35 is a standard bicycle component supported by left and right bearings fitted within bottom bracket tube 31. Crankshaft 3 S may have standardized square ends for attachment to matching sockets formed in the inner faces of inner hubs 36 and 37 of the one-way clutch mechanisms (attachment bolts not illustrated).
Pedal 8, crank arm 11, outer hub 41, roller clutch 39 and inner hub 37 operate in a similar manner to the right side components described above, thereby imparting only clockwise rotation to crankshaft 35 and sprocket 9.
General purpose roller clutches such as the one shown in FIG 4 require many precisely made moving parts as well as very strong hubs to withstand the internal cam forces. FIG 5 is a partially exploded view of a one-way ratchet clutch that is adapted to the present invention and that does not require such expensive fabrication.
The left and right one-way ratchet clutches are comprised of left and right ratchet hubs 43, 44.
Ratchet hubs 43, 44 have a series of ratchet detents formed around their outer circumference. Each crank arm 10, 11 has two pivot shafts projecting from its inner surface. Crank pivot shaft S 1 (visible only on right crank) is received by ratchet hub bearing 45, thereby supporting the crank/pedal assembly while permitting it to rotate with respect to ratchet hub 44. Pawl pivot shaft 54 (visible only on left crank arm) receives pawl 46 and SO such that their tips can swing into engagement with detents on ratchet hubs 43, 44. Ratchet hub bearing 4S occupies approximately half the depth of the ratchet hub thereby leaving space for a square socket for mating the hub omo the standard square end of bicycle crankshaft 35.
Left and right pawl 50, 46 are pivot mounted to the inside of crank arms 10 and 11 and are each spring biased to maintain tip pressure onto the ratchet hub (springs not illustrated). Simple spring configurations for biasing the pawl towards its ratchet hub will be obvious to those practiced in the art. For example: a coil spring stretched and secured between a fixation point on the crank arm and another fixation point on the pawl.
Another suitable pawl biasing means might be a hairpin spring mounted on the crank arm so as to urge the pawl to pivot towards the ratchet.
Each pawl is asymmetrically positioned to provide cam action and spring biased such that while rotating counterclockwise with respect to its ratchet hub, the pawl tip slides freely over the hub's textured surface. However, while rotating clockwise with respect to its ratchet hub, the tip of each pawl is engaged by cam action into the ratchet hub's textured surface, thereby locking the crank arm to the ratchet hub. Pawl pivot shaft 54 is located at a distance from crank pivot shaft 51 that provides the appropriate cam force needed to securely mate the two parts while minimizing friction and ratchet noise during freewheeling.
In order to minimize backlash when the direction of crank rotation is reversed, the ratchet detents should be closely spaced and matched to the characteristics of the pawl tips that mate with them. The ratchet hub's engagement surface may have distinct "gear-like" detents such as those illustrated in FIG 5 however much smoother textures may also be employed provided the texture is appropriate to the pawl's; tip shape, spring biasing force, hardness and cam actuation geometry.
The one-way clutches illustrated in FIG 5 has only a single pawl that beans onto each ratchet hub. In another embodiment (not illustrated) a second pawl bears onto the opposite side of the hub thereby improving grip and reducing component stress.
To support a second pawl, the crank arms are extended rearwards past their respective ratchet hubs to support an additional pawl pivot shaft. A rear-mounted pawl identical to pawl 46 is spring biased and pivoted on this rear pawl pivot shaft so as to engage ratchet hub 44 in an identical manner to the front-mounted pawl described above.
Referring to FIG 6: the rider's upright standing position provides relaxed and efficient posture for actuating the present invention however it is aerodynamically inefficient. To compensate for this loss in efficiency, fairing 47 may be attached to the front components of bicycle 1 using suitable brackets (not illustrated).
Although the present invention has been described with reference to particular examples, it is recothat various minor mechanical modifications are possible when implementing its inventive concepts.
Crank arms 10 and 11 are constrained to operate within the front quadrant of possible motion by means of cable 16 and pulley 17. Efficient force geometry is mairnained when each crank arm operated within a range of approximately +/- 45 degrees from the horizontal (see FIG 8 for an orthogonal illustration of typical crank motion range).
Cable 16 is typically a mufti-strand steel cable. Pulley 17 is a conventional pulley assembly comprised of a disk grooved around its circumference to receive cable 16 and rotateably affixed within a supporting shell having an upper swivel or loop for suspending the assembly. Pulley hanger 18 is a tube clamp assembly having a U
shaped loop projecting from its lower surface, thereby providing means for suspending pulley 17.
The pulley hanger shown is a two-piece clamp screwed together however other clamping brackets will be obvious to those practiced in the art. For example: a "hose clamp" or "C
clamp" type of pulley hanger are within the scope of the invention. When the engagement loop portion of pulley 17 is loosely engaged through the engagement loop portion of pulley hanger 18, the orientation of pulley 17 can swivel freely within a certain range, thereby permitting cable 16 to track smoothly into the pulley's groove as the cable's orientation changes in response to pedal motion.
Cable 16 passes over pulley 17 and affixes to right pedal 7 and left pedal 8.
The rider steps alternately on pedals 7 and 8 to impart forward rotation to front sprocket 9, chain 6, rear sprocket 5 and rear wheel 3. When the length of cable 16 and the location of pulley 17 are configured as illustrated in FIG 1 and FIG 3:
1 ) Depressing either pedal will simultaneously cause the opposite pedal to rise, thereby permitting the rider to oscillate both crank arms within the forward quadrant using a stepping motion.
2) By applying equal foot pressure, the rider can coast comfortably while standing on both pedals suspended at the same height.
3) The descending crank arm is arrested at the bottom of its desired motion quadrant when no more cable slack is available for further lifting of the ascending crank. This permits the lowered pedal to bear the entire weight of the rider while the opposite leg is freed for other activities such as push starting the vehicle from a stop or to actuating a foot operated rear brake (see FIG. 3).
Cable 1 b is affixed at one end to rotateable pedal 8 and at the other end to rotateable pedal 7. Pedals 7,8 may be either a conventional bicycle pedal threaded flush through the crank arm (not illustrated). Alternatively, each pedal's axle may be extended through the crank arm as shown by axle extensions 14, 15.
Referring to FIG 3, it is evident that due to the short distance between pulley 17 and raised pedal 8, if cable 16 were attached directly to the pedal, very considerable lateral bending forces would be generated in crank arm 11 and one-way clutch 13 when the rider's full weight is applied to pedal 7. Therefore, pedal axle extensions 14 and 15 are provided to bring the pedal's attachment point closer to the centerline of bicycle 1, thereby reducing and balancing stresses within the drive train components.
Referring back to FIG 1, even when pedal 8 is fully raised, the larger "adult sized" bicycle frame leaves a large distance between the raised pedal and pulley 17, thereby causing cable 16 to be more inline with crank arm 11. Given this nearly linear cable-to-crank arm geometry, pedal axle extensions 14 and 15 may be shortened or omitted when fitting the invention to large sized bicycle frames.
Another means for reducing excessive lateral forces onto the crank arms is to increase the diameter of pulley 17 beyond that shown in the drawings. A well-implemented embodiment of the invention will minimize stresses by using a balanced combination of the frame size, the length of pedal axle extensions 14, 15, the diameter of pulley 17 and the rigidity of the transmission the components such as bearings, crank arms, pivots etc.
A suitable cable-to-pedal fixation means is to form a loop at each cable end (not illustrated). Each loop passes around a bicycle pedal's axle such that the loop is captured in tire groove between the pedal's rotateable portion and the outer side of the crank arm (not illustrated). The cable loop size may adjustable, thereby permitting the rider to adjust the length of cable 16, which in turn adjusts the lower limit of pedal travel. A bolt threaded into the inboard end of the pedal axle might also be used to secure a suitably terminated cable end to the pedal/crank assembly (not illustrated). To minimize friction, the cable fixation should be loose enough to pivot in response to angular changes to tensioned cable 16.
Similar fixation means may be employed for affixing the cable ends to the inner ends of pedal extensions 14,15 when such extensions are required for fitting the invention tv smaller bicycle frames. FIG 5 illustrates another suitable fixation means:
cable ends 52 fit into slots 53 farmed in the ends of pedal extensions 14 and 15. A
recess formed in the underside of each slot 53 engages cable end 52 to secure it in place.
Other cable fixation means will be obvious to those practiced in the art.
Referring now to FIG 8: modified seat post 32 may be provided that compensates for the more forward rider position necessitated by pedal motion being restricted to the forward quadrant. Seat post 32 telescopes within seat tube 29 in tl~ same manner as the stock (strait) version to provide vertical seat adjustment. Modified seat post 32 includes a horizontal portion that displaces the fixation point of seat 4 towards tl~
front of bicycle 1.
The rider can thereby slide and clamp the seat forward at a location where their center of gravity is centered over pedals 7 and 8. Typical riders will also raise the seat somewhat to compensate for the pedals not descending as low as on a stock bicycle.
Handlebar 21 may also be modified to move the rider's hands somewhat up and forward (not illustrated).
FIG 2 illustrates a smaller "children's sized" bicycle frame adapted and fitted to an embodiment of the present invention. A standing adult rider would be too tall to make use of a seat, therefore the seat is omitted to save weight a~ provide for a ~re compact assembly when stored. Handlebar 21 is adjustable in height by means of telescopic tube 20 and suitable clamping fixture (not illustrated). To further reduce the vehicle's overall height, telescopic tube 20 is hinged to head tube 27 by means of hinge joint 19 having a suitable friction clamping means for fixing telescopic tube 20 at the desired angle. To facilitate storage, handlebar 21 is collapsed into telescopic tube 20 and hinge joint 19 is loosened whereupon the entire handlebar assembly is folded down towards rear wheel 3.
To minimize the bicycles storage footprint and also prevent the parked vehicle from falling over, front wheel 2 may be raised backwards past rear wheel 3 while the angle and extension of handlebar 21 is adjusted such that rear wheel 3, and the left and right bar ends 22 form a support triangle on the ground (not illustrated).
Handlebar 21 may be a hinged T as illustrated however other collapsible or folding handlebar configurations are also within the scope of the invention.
High-rise "cow horn" style handlebars affixed by a conventional handlebar clamp may also be loosened and then folded rearward. Collapsible T style bars that have removable left and right handgcips may also be used. To reduce the overall width of the bicycle during storage, pedals 7 and 8 may be foldable. Such foldable pedals are commercially available (e.g.: Wellgo model FP-3 or MKS model FD2).
An alternate means of arresting pedal motion within the forward quadrant is sometimes useful when frame geometry forces pulley holder 18 to be ai~xed at too high an angle. FIG 2 illustrates pulley 17 and pulley holder 18 mounted only slightly forward of the rotational axis of crank arms 10 and 11, thereby causing the crank's upper limit of motion to be near vertical. Therefore, means are provided to constrain pedal motion within the desired +/- 45 degrees from horizontal. Pedal stop 23 is a tube clamp fixture similar to pulley holder 18 that is affixed to down tube 30 at a location where it obstructs pedal extensions 14 and 15 from rising higher than is consistent with good quasi-linear pedaling efficiency. Notch 33 is formed in pedal stop 23 such that it blocks pedal axle extensions 14, 15 while permitting cable 16 to run freely towards pulley 17 (see FIG 7 for clearer detail).
A truly miniature embodiment of the invention suitable for carrying onto mass transit vehicles requires a specially constructed frame arid associated components.
Referring to FIG 3: spar frame 48 replaces the triangulated tube frames used in previously described embodiments. Spar frame 48 may be a length of rectangular section aluminum tubing having rear cutouts on its upper and lower surface that receive rear wheel 3 to form rear fork 26. Head tube 26 is typically welded to the front end of spar frame 48 and may include strengthening gusset 49.
Head tube 26 may be shaped to provide a handhold for conveniently carrying the folded bicycle. If strengthening gusset 49 is included, its rear edge may also be rounded as shown to provide a comfortable handl~ld that is closer to rear wheel 3 than head tube 26. The rounded handhold facilitates transport of the folded bicycle while being earned straight-armed (like a briefcase) without having the vehicle's rear wheel hitting the ground. A shoulder strap may also be provided that engages onto either head tube 27 or strengthening gusset 49, thereby permitting the rider to sling the folded bicycle their arm for convenient carrying. To facilitate carrying in this manner, handlebar 21 and pedals 7, 8 may include folding or collapsible means as previously described.
To reduce weight, front fork 25 may include only a single leg as shown or may be configured conventionally with two legs as illustrated in FIG 1 and FIG 2. The step drive mechanism for this embodiment is comprised of the same components and configuration as that used in the medium and large sized embodiments described above.
Bottom bracket tube 31 is welded to the top of spar frame 48 for housing the crankshaft and one-way clutches 12, 13 (detailed below). Spmckets 9 and 5 are engaged to either an endless chain or an endless belt (neither illustrated). The diameter of rear wheel 3, rear sprocket 5 and front sprocket 9 may be made larger or smaller as necessary in order to achieve the gear ratio appropriate to the power delivery characteristics of the step drive mechanism.
A conventional hand-operated caliper brake may be employed for stopping the vehicle (not illustrated). To reduce weight a~xi simplify construction, foot operated brake 34 may be provided. Foot brake 34 is a rigid or semi-rigid strap of metal or similar material. Foot brake 34 is secured to spar frame 48 and/or bottom bracket tube 31 such that it cantilevers backwards, closely above rear wheel 3. When the rider wishes to stop, foot pressure is applied onto the top of foot brake 34, thereby bending the resilient strap down into braking contact with rotating rear wheel 3. Actuation of the brake may be either by flexion of a resilient strap at~xed as described above or by means of a hinge and return spring fixation between the brake the spar frame (not illustrated).
FIG 4 is an exploded view of the one-way clutches 12, 13 used to transform quasi-linear pedal motion into rotation of rear wheel 3. These particular left and right clutches are standard off the-shelf indexing roller clutches such as the Torrington FCB-30 or the Stieber NFR-35. Such clutches are comprised of left and right outer bearing hubs 41, 42 coupled to left and right inner bearing hubs 37, 38 via left and right roller clutches 39, 40. Roller clutches 39 and 40 utilize tiny internal ramps and springs that bias a plurality of rollers such that they jam between the inner and outer hubs when rolled in one direction yet act as an anti-friction bearing when rolled in the opposite direction.
Right pedal 7 rotates crank arm 10, which in turn drives outer bearing hub 42.
When hub 42 rotates clockwise, roller clutch 40 jams against inner hub 38, thereby causing sprocket carrier 36 and sprocket 9 to rotate clockwise with attendant forward propulsion of the rear wheel. Sprocket 9 and sprocket carrier 36 may be formed as a single monolith however the use of two discrete components permits sprocket 9 to be a standard off the-shelf bicycle component. While pedal 7 is being lifted by cable 16, outer bearing hub rotates counterclockwise with respect to inner hub 38 therefore roller clutch 40 disengages power transmission from the rear wheel.
While coasting with no pedal movement, forward rotation of wheel 3 causes forward rotation of rear sprocket 5, chain (or toothed belt) 6, front sprocket 9, sprocket carrier 36 and inter hub 38. Roller clutch 40 will however decouple inner hub 38 from outer hub 42, thereby enabling the pedals to remain stationary while at the same time eliminating the need for the stacxlard bicycle freewheel normally located between rear hub 24 and sprocket S.
Crankshaft 35 is a standard bicycle component supported by left and right bearings fitted within bottom bracket tube 31. Crankshaft 3 S may have standardized square ends for attachment to matching sockets formed in the inner faces of inner hubs 36 and 37 of the one-way clutch mechanisms (attachment bolts not illustrated).
Pedal 8, crank arm 11, outer hub 41, roller clutch 39 and inner hub 37 operate in a similar manner to the right side components described above, thereby imparting only clockwise rotation to crankshaft 35 and sprocket 9.
General purpose roller clutches such as the one shown in FIG 4 require many precisely made moving parts as well as very strong hubs to withstand the internal cam forces. FIG 5 is a partially exploded view of a one-way ratchet clutch that is adapted to the present invention and that does not require such expensive fabrication.
The left and right one-way ratchet clutches are comprised of left and right ratchet hubs 43, 44.
Ratchet hubs 43, 44 have a series of ratchet detents formed around their outer circumference. Each crank arm 10, 11 has two pivot shafts projecting from its inner surface. Crank pivot shaft S 1 (visible only on right crank) is received by ratchet hub bearing 45, thereby supporting the crank/pedal assembly while permitting it to rotate with respect to ratchet hub 44. Pawl pivot shaft 54 (visible only on left crank arm) receives pawl 46 and SO such that their tips can swing into engagement with detents on ratchet hubs 43, 44. Ratchet hub bearing 4S occupies approximately half the depth of the ratchet hub thereby leaving space for a square socket for mating the hub omo the standard square end of bicycle crankshaft 35.
Left and right pawl 50, 46 are pivot mounted to the inside of crank arms 10 and 11 and are each spring biased to maintain tip pressure onto the ratchet hub (springs not illustrated). Simple spring configurations for biasing the pawl towards its ratchet hub will be obvious to those practiced in the art. For example: a coil spring stretched and secured between a fixation point on the crank arm and another fixation point on the pawl.
Another suitable pawl biasing means might be a hairpin spring mounted on the crank arm so as to urge the pawl to pivot towards the ratchet.
Each pawl is asymmetrically positioned to provide cam action and spring biased such that while rotating counterclockwise with respect to its ratchet hub, the pawl tip slides freely over the hub's textured surface. However, while rotating clockwise with respect to its ratchet hub, the tip of each pawl is engaged by cam action into the ratchet hub's textured surface, thereby locking the crank arm to the ratchet hub. Pawl pivot shaft 54 is located at a distance from crank pivot shaft 51 that provides the appropriate cam force needed to securely mate the two parts while minimizing friction and ratchet noise during freewheeling.
In order to minimize backlash when the direction of crank rotation is reversed, the ratchet detents should be closely spaced and matched to the characteristics of the pawl tips that mate with them. The ratchet hub's engagement surface may have distinct "gear-like" detents such as those illustrated in FIG 5 however much smoother textures may also be employed provided the texture is appropriate to the pawl's; tip shape, spring biasing force, hardness and cam actuation geometry.
The one-way clutches illustrated in FIG 5 has only a single pawl that beans onto each ratchet hub. In another embodiment (not illustrated) a second pawl bears onto the opposite side of the hub thereby improving grip and reducing component stress.
To support a second pawl, the crank arms are extended rearwards past their respective ratchet hubs to support an additional pawl pivot shaft. A rear-mounted pawl identical to pawl 46 is spring biased and pivoted on this rear pawl pivot shaft so as to engage ratchet hub 44 in an identical manner to the front-mounted pawl described above.
Referring to FIG 6: the rider's upright standing position provides relaxed and efficient posture for actuating the present invention however it is aerodynamically inefficient. To compensate for this loss in efficiency, fairing 47 may be attached to the front components of bicycle 1 using suitable brackets (not illustrated).
Although the present invention has been described with reference to particular examples, it is recothat various minor mechanical modifications are possible when implementing its inventive concepts.
Claims (10)
1) A bicycle drive mechanism for transforming quasi-rectilinear pedaling motion into rotational propulsive motion comprised of:
.cndot. a crankshaft mounted transversely on the bicycle;
.cndot. a rotary drive element affixed to the crankshaft and coupled for transfer of power to the rear wheel by an endless, flexible drive element;
.cndot. a pair of crank arm and foot pedal assemblies, each coupled to an end of the crankshaft via a one-way clutch which constrains the crankshaft and rotary drive element to rotate towards the front of the bicycle;
.cndot. a pulley, flexibly affixable to the frame of the bicycle and located at a point above the highest point in the pedal's forward quadrant of motion;
.cndot. a length of cable passed over said pulley and affixed at its ends to the left and right pedals respectively said cable's length and said pulley's location being configured such that when a crank arm and pedal assembly is raised to the location where pedal to pulley distance is minimized, cable tension arrests the opposite crank arm and pedal assembly at the bottom of its desired quadrant of motion.
.cndot. a crankshaft mounted transversely on the bicycle;
.cndot. a rotary drive element affixed to the crankshaft and coupled for transfer of power to the rear wheel by an endless, flexible drive element;
.cndot. a pair of crank arm and foot pedal assemblies, each coupled to an end of the crankshaft via a one-way clutch which constrains the crankshaft and rotary drive element to rotate towards the front of the bicycle;
.cndot. a pulley, flexibly affixable to the frame of the bicycle and located at a point above the highest point in the pedal's forward quadrant of motion;
.cndot. a length of cable passed over said pulley and affixed at its ends to the left and right pedals respectively said cable's length and said pulley's location being configured such that when a crank arm and pedal assembly is raised to the location where pedal to pulley distance is minimized, cable tension arrests the opposite crank arm and pedal assembly at the bottom of its desired quadrant of motion.
2) The bicycle drive mechanism described in Claim 1 wherein each one-way clutch is comprised of: a ratchet hub affixed to each end of said crankshaft;
a bearing fined into the outer side of said ratchet hubs for rotateable mounting of said crank arms and at least one spring biased pawl, said pawls being pivot-mounted to the inner face of said cranks such that their tips are selectably engaged onto said ratchet hub by cam action.
a bearing fined into the outer side of said ratchet hubs for rotateable mounting of said crank arms and at least one spring biased pawl, said pawls being pivot-mounted to the inner face of said cranks such that their tips are selectably engaged onto said ratchet hub by cam action.
3) The bicycle drive mechanism described in Claim 1 wherein the components are configured for conversion of an existing bicycle having a conventional rotary crank drive.
4) The bicycle drive mechanism described in Claim 1 further comprising a children's sized bicycle and a folding handlebar.
5) The bicycle drive mechanism described in Claim 1 finer comprising an adult's sized bicycle.
6) The bicycle drive mechanism described in Claim 1 further comprising a miniature, folding bicycle having a spar frame small enough for carrying onto mass transit vehicles.
7) The bicycle drive mechanism described in Claim 1 further comprising a seat post adapted for mounting a bicycle seat forward of its conventional location.
8) The bicycle drive mechanism described in Claim 1 further comprising a foot-operated brake comprised of a deformable frictional element cantilevered over the bicycle's rear wheel.
9) The bicycle drive mechanism described in Claim 1 further comprising inward pedal axle extensions for attachment to said cable.
10) The bicycle drive mechanism described in Claim 1 further comprising a blocking element for limiting upward movement of said crank arm and foot pedal assemblies.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002414681A CA2414681A1 (en) | 2003-01-13 | 2003-01-13 | Oscillating step drive for a bicycle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002414681A CA2414681A1 (en) | 2003-01-13 | 2003-01-13 | Oscillating step drive for a bicycle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2414681A1 true CA2414681A1 (en) | 2004-07-13 |
Family
ID=32660894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002414681A Abandoned CA2414681A1 (en) | 2003-01-13 | 2003-01-13 | Oscillating step drive for a bicycle |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2414681A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1688344A3 (en) * | 2005-02-02 | 2007-10-10 | Chong, Ok Yeo | Improved multifunctional pedaling motion bicycle |
| GB2438183A (en) * | 2006-05-19 | 2007-11-21 | Robert Maclean Muirhead | Bicycle with arcuately reciprocating pedal crank arms |
| FR2914723A1 (en) * | 2007-04-03 | 2008-10-10 | Joel Martin | PROPULSION MECHANISM WITH TWO INDEPENDENT ACTUATORS |
| ITMI20081836A1 (en) * | 2008-10-16 | 2010-04-17 | Specialities S R L | ASSISTIVE DEVICE AND PEDALING STABILIZATION. |
| CN109050773A (en) * | 2018-08-07 | 2018-12-21 | 张文成 | Reversely foot-operated bicycle |
-
2003
- 2003-01-13 CA CA002414681A patent/CA2414681A1/en not_active Abandoned
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1688344A3 (en) * | 2005-02-02 | 2007-10-10 | Chong, Ok Yeo | Improved multifunctional pedaling motion bicycle |
| AU2006200233B2 (en) * | 2005-02-02 | 2010-12-23 | Chong, Ok Yeo | Improved multifunctional pedaling motion bicycle |
| GB2438183A (en) * | 2006-05-19 | 2007-11-21 | Robert Maclean Muirhead | Bicycle with arcuately reciprocating pedal crank arms |
| FR2914723A1 (en) * | 2007-04-03 | 2008-10-10 | Joel Martin | PROPULSION MECHANISM WITH TWO INDEPENDENT ACTUATORS |
| WO2008142251A2 (en) * | 2007-04-03 | 2008-11-27 | Martin Joel | Propulsion mechanism with two independent actuators |
| WO2008142251A3 (en) * | 2007-04-03 | 2009-02-19 | Joel Martin | Propulsion mechanism with two independent actuators |
| ITMI20081836A1 (en) * | 2008-10-16 | 2010-04-17 | Specialities S R L | ASSISTIVE DEVICE AND PEDALING STABILIZATION. |
| CN109050773A (en) * | 2018-08-07 | 2018-12-21 | 张文成 | Reversely foot-operated bicycle |
| CN109050773B (en) * | 2018-08-07 | 2024-02-27 | 张文成 | Reverse pedal bicycle |
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