This application is a continuation-in-part of United States Patent Application Serial No. 228,264 of Steven E. Titcomb filed January 28, 1981, for An Operator Powered Vehicle.

FIELD OF THE INVENTION

This invention relates generally to operator powered vehicles and more particularly to bicycles, bicycle frames and bicycle drive mechanisms.

BACKGROUND OF THE INVENTION An operator powered vehicle, especially a bicycle, includes three elements with which the operator may interact. These elements are the handle bars, the seat, and the pedals. Heretofore, bicycles have deployed these three elements so that the weight of the operator which may be used to propel the bike is distributed between the seat and the handle bars, such as in the bicycle shown in U.S. Patent 3,375,023. Bicycles of this design rely primarily on the muscle power provided by the operator's legs. Also, the pedals move with a rotary motion so that the weight of the operator is not always directed downwardly on the pedals and so that the pedal position shifts back and forth along the length of the bicycle with respect to the operator's center of gravity. Further bicycle refinement has included a lowering of the handle bars which encourages the rider to lean forward to reduce his air resistance while in motion, as illustrated by the drawings in U.S. Patent 3,938,403. This configuration has the effect of further displacing the potential driving force of the operator's weight by shifting his center of gravity forward so that a part of his weight is placed over the front wheel and only a part

of his weight is available to provide a downward force on the pedals. Often in such bicycles, the center of gravity of the operator is displaced outside of his body. An additional adverse consequence of the operator position on the vehicle in relation to the seat, the handle bars, and the pedals is that the operator often has vision difficulties because he can't see motorists, nor can they see him, and the operator is very uncomfortable while riding the bicycle. Because the frame is high off the ground, the operator finds it difficult to easily mount or dismount from the bicycle.

A suggested solution to the mount/dismount problem and to the weight distribution problem is found in a pedal powered scooter. However, prior art scooters, with their small pedal displacement, inefficient drive mechanisms and short wheel bases are generally unsuitable for anything more than short distance trips, at low speeds. As a result, such scooters are generally restricted for use as a toy. Additionally, the drive systems of prior art scooters have serious drawbacks. In some scooters, such as those found in U.S. Patents 2,053,835 and 2,062,830, the treadles have a rear pivot, thus potentially causing the scooter to catapult over the free end of the treadle, should the drive mechanism break. In other scooters, such as that shown in U.S. Patent 2,053,835, the drive cable is connected to the rear axle hub, in a manner which prevents the scooter from being moved in a backward direction. If such a scooter is pushed backwardly, or slides backwardly down a hill, drive mechanism or transmission damage may result. Although bicycles or scooters which fold or disassemble are available, as shown in U.S. Patents 4,111,447 and 3,220,748, few of such vehicles may be disassembled quickly and easily to be transported

conveniently in an urban environment. Also, such vehicles are bulky and awkward in their disassembled state, and they occupy a large amount of floor space, making them inconvenient for carrying on a mass transmit vehicle.

SUMMARY OF THE INVENTION Broadly speaking, the vehicle of the present invention provides for an arrangement of the pedals, handle bars and seat so that the operator may augment the drive force which his legs provide to the pedals by an upward force exerted by his arm muscles on the handle bars of the bicycle and by his own body weight. More specifically, lever-like pedal arms are provided wherein the operator of the bicycle assumes a substantially upright position and his center of gravity is disposed generally above the pedals arms and is displaced from the pivot point of the pedal arms. The pedal arms pivot about one end and move with an up and down motion and not a rotary motion, so that the other end of the pedal arm is always disposed between the one or pivot end and either the front wheel or the rear wheel. This type of motion allows the operator's center of gravity to remain generally above the other end of the pedal arm at all times and permits the operator to apply his weight alternatively to one or to the other of the pedal arms or to both pedal arms to augment the muscle force provided by his legs. The handle bars extend backwardly towards the operator to overlie the pedal arms so that the operator may remain in an upright position and further augment the downward force on the pedals by an upward force applied with his hands against the handle bars. This arrangement permits more efficient utilization of the forces provided by the operator's weight and by his

arm strength. In a preferred embodiment, the pedal arms have a forward pivot and extend rearwardly to minimze the danger of injury should the driving cable snap. However, a rear pivot pedal arm is also within the scope of this invention.

Drive cables transfer to the rear wheel the force applied to the pedal arms. A two cable drive may be used so that the pedal arms move either independently of one another, or a single cable drive may be employed in which the pedal arms operate in opposed relation so that as one pedal arm goes down, the other must go up. _. In either embodiment, the cables are coupled to the rear wheel hub by being wrapped therearound without being secured thereto. This feature permits the vehicle to be moved in a backwardly direction without snapping the cable. The cable may be maintained in an appropriately tensioned state by a spring, by an expanding hub assembly, or by a spring tensioned reel to prevent the cable from becoming unraveled from the wheel hub. The vehicle of the present invention further provides for ease of disassembly and transportation when the bicycle itself is not being ridden. The vehicle may be disassembled into components, one component comprising the front wheel and the handle bars, and another component comprising the frame, he pedal arms, and the rear wheel. If a seat is provided, it would comprise a third component. In a preferred embodiment, the point at which disassembly may be accomplished is the steering pivot. When disassembled, the bicycle is sufficiently compact to provide for easy transportation. In addition, the disassembled bicycle has a large vertical dimension and occupies very little horizontal floor space so that it may be easily carried on a mass transit vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned features of this invention and the manner of attaining them will become more apparent and better understood by reference to the following description of the accompanying drawing, wherein:

FIG. 1 is a side pictorial view of one embodiment of the vehicle of the present invention without a seat; FIG. 2 is a side pictorial view of one embodiment of the vehicle of the present invention with a seat; FIG. 3 is a partial cross-sectional view of the pedal of the vehicle of FIGS. 1 and 2 deployed in the riding position;

FIG. 4 is a partial cross-sectional view of the pedal of the vehicle of FIGS 1. and 2 folded into storage position;

FIG. 5 is a cross-sectional view of one pedal arm of the invention;

FIG. 5A is a cross-sectional view of another pedal arm of the invention; FIG. 6 is a partial cut-away showing the drive cable in the pedal arm of FIG. 5;

FIG. 7 is a partial rear view of the frame and rear pedal pulleys;

FIG. 8 is a cross-sectional view of the frame and pedal pulley mounting of FIG. 7;

FIG. 9 is a schematic view of a single drive cable routing for the pedal pulleys of FIG. 7;

FIG. 10 is a cross-sectional view of the frame and cross over pulley of in FIG. 9; FIG. 11 is a front view of a steering pivot assembly of the vehicle of FIG. 1;

FIG. 12 is a partial pictorial view of the steering assembly of the vehicle of FIG. 1;

FIG. 13 is a side view of an embodiment of the vehicle of FIG. 2 having a cable reel;

FIG. 14 is a side view of another embodiment of the vehicle of FIG. 2 employing a multi-speed hub; FIG. 15 is a perspective view of a unidirectional hub drive and sprocket drive of the bicycle of FIG. 14;

FIG. 16 is a side view of spring type unidirectional hub drive of this invention; and

FIG. 17 is a partial cut away perspective view of the stop plate of FIG. 15;

FIG. 18 is a side elevation, with parts broken away, of a further embodiment of the present invention;

FIG. 19 is a plan view of the embodiment of FIG. 18; FIG. 20 is a front elevation of the embodiment of FIG. 18;

FIG. 21 is a front elevation with parts broken away of the portion of the steering mechanism used in collapsing the handlebars; FIG. 22 is a side elevation of the embodiment of FIG. 18 showing the seat and the handlebars collapsed; and

FIG. 23 is a cross-sectional representation of a further embodiment of the coupling of the cable to the drive wheel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing and more specifically to FIG. 1, a vehicle 200 is shown according to one embodiment of the invention. The basic vehicle 200 comprises front and rear wheels 36 and 46 respectively, a frame 32, a steering assembly 220, a force transmission assembly 210, and a rear hub subassembly 215. Force transmission assembly 210 typically includes pedal arms

38A and 38B having respective pedals 40A and 40B. The force transmission assembly 210 conveys the total force produced on pedal arms 38A and 38B by the operator 30 to the rear wheel 46 via a rear hub subassembly 215, as discussed below.

Each of the above-referenced assemblies is deployed relative to the vehicle frame in a manner which maximizes the propelling force supplied by the operator 30 as well as which renders vehicle 200 convenient to ride and transport in an urban environment. Steering assembly 220 includes handlebars 31A and 31B which extend backwardly towards operator 30 and which are splayed outwardly so that the ends thereof are disposed on either side of operator 30. Handgrips 353A and 353B (Fig. 12) on the ends of respective handlebars 31A and 31B allow operator 30 to grasp the handlebars. Handgrips 353A and 353B generally overlie or are positioned vertically above pedal arms 38A and 38B of the force transmission assembly 210. This configuration allows the operator 30 to propel the vehicle while in a substantially vertically erect or upright position, called a forced weight position. Since operator 30 is generally in an upright position, his center of gravity 33 is generally vertically aligned with his feet and with pedals 40A and 40B. In this configuration, the center of gravity 33 of the operator 30 resides within or in close proximity to his body. This forced weight position permits the operator 30 to augment with his body weight the driving force normally provided only by his legs. Additionally, since handgrips 353A and 353B overlie respective pedal arms 38A and 38B, operator 30 may provide an additional downward force to the pedal arms by a lifting force applied upwardly by his arms on hand grips 353A and 353B. The extension of handlebars 31A and 31B towards operator 30 is possible

because the pedal arms 38A and 38B exhibit only a limited up and down pivotal motion and not a rotary motion as in most bicycles, and this reduces the forward knee action which would otherwise interfere with handlebars 31A and 31B. Typically, for a body weight of 160 pounds and an " operator arm lifting force of appro imately 90 to 120 pounds per arm, a total downward drive force to the pedal arm of 340 to 400 pounds will result.

An optional adjustable seat 52 and support 51 are shown in Fig. 2. The seat 52 is so disposed as to provide the operator with a convenient rest as well as the optimal upright position described above. The seat 52 does not interfere with the operation of the vehicle 200 described above and hereunder. Seat 52 is not essential to this invention, but may be provided for rider comfort.

The vehicle of the present invention also has a frame 32 which closely spaced from the ground surface to permit easy mounting and dismounting from the vehicle. Frame 32 may be formed of tubing or a solid member which extends from the vicinity of the axis of rotation of rear wheel 46 to steering assembly 220 at a point between handlebars 31A and 31B and front wheel 36. Frame 32 forms a small angle with respect to the ground. The location of handle bars -allows the operator 30 to maintain a substantially upright position at all times. This low positioning of the frame is partially a result of the use of a non-triangulated frame, in contrast to most bicycles. The elements of the force transmission assembly 210 are shown in FIGS. 1-10, 15 and 16. The force transmission assembly 210 generally includes pedal arms 38A and 38B, as indicated, associated pedals 40A and 40B, at least one flexible cable 42, pulleys 56 and 60, at

least one unidirectional hub 70, and cable tensioning means shown in Figs. 5A, 13 and 16. The various embodiments and the interconnection of each of the elements of the force transmission assembly 210 are explained in greater detail hereunder.

Pedal arms 38A and 38B of the vehicle are of the lever type and are disposed opposite one another on each side of frame 32. Pedal arms 38A and 38B, in this embodiment, have a pivot 37 forward of their associated pedals 40A and 40B for safety to prevent the vehicle from being catapulted forward if the drive should snap, as may happen in a rear pivot system. However, a vehicle having a rear pivot pedal arms is within the scope of this invention. Pedals 40A and 40B are pivotally connected to the distal ends of respective pedal arms 38A and 38B and are adapted to receive the operator's feet and the downward force exerted thereby. The pedal arms 38A and 38B are pivoted with an up and down motion and not a rotary motion. Pedals 40A and 40B are permitted to travel in an arc which is, at all times, positioned between pivot 37 and rear wheel 46. The exact size of the arc used is determined by operator 30 who may use the entire available pedal arm travel or who may use only a portion thereof. Most of the force is transmitted to the pedal arm at the bottom -of the arc and thus, that is the most important part thereof. In this manner, the horizontal displacement of the point where the operator applies force, i.e, the pedals 40A and 40B, is minimized. By minimizing horizontal displacement, the operator 30 may more easily maintain a more efficient riding position in which he is vertically positioned, and in which his center of gravity remains disposed at all times generally over the pedals 40A and 40B and behind pivot 37. Also, his knees will not strike the steering assembly 220.

The propelling force provided by the operator 30 as applied to the pedals 40A and 40B is translated by downward motion of pedals 40A and 40B into a force or tension applied to a drive cable 42 causing a forward longitudinal movement thereof. This forward motion of cable 42 drives rear hub subassembly 215. Either a single cable or a two cable system may be used. In either system, the bike frame support typically has two identical diagonally disposed rear wheel supports 58A and 58B, as shown in Figs. 6-8. Supports 58A and 58B have pulleys 60A and 60B respectively over which drive cable 42 passes from respective pedal arms 38A and 38B. Pulley housings 62A and 62B, which surround respective pulleys 60A and 60B, assist in retention of the drive cable on the pulley during operation and provide protection, a covering and structural support for the pulleys 60A and 60B. The pulley arrangement exists in symmetrical relation on each side of the rear wheel, as shown in FIGS. 7 and 8. The rear wheel supports 58A and 58B, are connected and maintained in spaced relation by lateral support 64. An axle pin 66 passes through member 64 and serves to secure pulleys 60A and 60B and to provide an axis about which they may rotate. The two rear wheel support members 58A and 58B may be attached to the vehicle frame 32 as shown in FIG. 1 or they may be attached to the seat structure or seat support 51 as shown in FIG. 2.

One of the pedal arms 38A is shown in FIGS. 5 and 6. Drive cable 42 is secured at the pivot 37 and extends within arm 38A along the length thereof. Cable 42 is preferably wrapped around pivot 37 as shown in FIG. 5. A layer of resilient material 305 may be provided between cable 42 and pivot 37 to act as a shock absorber when the pedal reaches the lower end of its arc and the cable 42

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is taut. Material 305 provides a cushioning effect so that when the lower end of the arc is reached, downward pedal movement is not abruptly ended and the operator feels no discomfort. A pedal arm pulley 56A is disposed on the pedal arm adjacent pedal shaft 41A. Pulley 56A may be a nonrotatable cable guide as shown in FIG. 5 for a two cable system, or pulley 56A may be freely rotatable as shown in FIG. 5A, when cable 42 is spring loaded in a single cable system to be described below. A resilient shock absorber 287 is provided on cable 42 adjacent pulley 56A to cushion the impact between pulley 56A and pulley 60A when arm 38A is in a raised position. Pedal 38B is identical to pedal 38A and has the same corresponding elements. Pedal travel is limited on the upper end and lower end of the stroke by pulley housings 62A and 62B which strike shock absorbers 287 of associated pulleys 56A and 56B respectively of pedal arms 38A and 38B when pedal arms 38A and 38B are raised sufficiently high. FIGS. 9 and 10 show the cable arrangement and rear hub subasse bly of a single cable system. The rear hub subassembly includes an axle 181 and two independent hubs 70A and 70B rotatably mounted on axle 131. Hubs 70A and 70B are coaxial and are disposed on either side of wheel 46. Axle 181 is coupled* directly to wheel 46, while hubs 70A and 70B are independently coupled to axle 181 by unidirectional clutches 71A and 71B which are coaxial with and reside within respective hubs 70A and 70B. The drive cable 42 passes from pedal 40A of pedal arm 38A through its pulley 60A, as shown in FIGS. 7 and 8, to associated hub 70A. Cable 42 is wrapped spirally around hub 70A. Cable 42 then passes from hub 70A forwardly to a generally horizontally disposed pulley 66 mounted to supports 58A and 58B by bracket 67 (FIG. 10). Cable 42

passes over pulley 66 and extends from pulley 66 rearwardly to the other hub 70B. Cable 42 is wrapped spirally about hub 70B. Cable 42 then extends forwardly to pulley 60B and pedal 40B of pedal arm 38B. Cable 42 is wrapped about both hubs- 70A and 70B in a direction such that as pedal arm 38A is driven downwardly by the operator, associated hub 70A rotates in a forward or clockwise direction, as shown in Fig. 9 and hub 70B rotates in a rearward or counterclockwise direction, as viewed in Fig. 9. Conversely, downward motion of pedal arm 38B produces forward rotation of hub 70B and rearward rotation of hub 70A. Downward movement of the pedal on one side of the vehicle causes a simultaneous upward movement of the pedal on the other side of the vehicle, and the drive cable 42 is cycled back and forth between the pedals as they are moved alternately upwardly and downwardly. Pedal travel is limited by pulley housings 62A- and 62B which are struck by shock absorbers 287 of respective pedals 40A and 40B and which also prevent further downward movement of each pedal by limiting the upward movement of the other pedal. Clutches 71A and 71B only couple hubs 70A and 70B to axle 181 during forward rotation thereof, so that only foward movement of cable 42 drives wheel 46. Hubs 70A and 70B rotate respective clutches 71A and 71B freely about axle 181 during the rearward rotation thereof.

The cable of a single cable drive system must be maintained in a tensioned state during nonuse to prevent unraveling of cable 42 from hubs 70A and 70B. One type of tensioning device is spring 57 disposed in each pedal arm as found in FIG. 5A which shows an alternative configuration of pedal arm 38A of Fig. 5. Pedal arm 38B is identical to pedal arm 38A. Spring 57 may be used in conjunction with hubs 70A and 7OB and clutches 71A and

71B of FIG. 9 and can be used in the single cable drive . system only. One end of spring 57 is secured to cable 42, while the other end is secured to pivot 37. Although shown as an extension spring, spring 57 may be also a compression spring. A stop plate 281 having an aperture 283 through which cable 42 passes is provided to engage a stop 285 disposed on cable 42 adjacent a facing end of spring 57 to prevent over extension of spring 57. Spring 57 is disposed in each pedal arm 38A and 38B and serves to absorb the extra length of cable 42 and to urge both pedal arms 38A and 38B to a raised position during nonuse. This action keeps cable 42 wrapped about hubs 70A and 70B at all times. If the vehicle is moved rearwardly, cable 42 slips on hubs 70A and 70B without damage thereto, and springs 57 maintain cable 42 in a wrapped condition about hubs 70A and 70B, while tending to raise pedal arms 33A and 38B.

Another type of tensioning device which may be used in a single cable drive system is an expanding-type unidirectional element 170 shown in FIG. 16. Hubs 70A and 70B and clutches 71A and 71B of FIG. 9 would each be replaced by an element 170 in the rear hub subassembly, and the pedal arms as shown in Fig. 5 without springs 57 are used in this embodiment. A cross-sectional view of element 170 shows a cylindrical hub 172, spring 173 and cable 42 wrapped about hub 172. Hub 172 is coupled to axle 181 by unidirectional clutch 171. There are two parallel collars 175 on either side of hub 172 to provide for lateral retention of the spring 173 and to retain drive cable 42 within the element 170. Spring 173 is typically a strip of highly resilient metal which is wrapped about cylindrical hub 172. Spring 173 is anchored along edge 177 by insertion into transverse slot 179 which is formed in hub 172 and which extends

thereacross between collars 175. A pin 178 is driven through a hole in collar 175 to secure edge 177 of spring 173. A slot 191 is provided in collar 175 to permit the installation of spring 173 by the lateral insertion thereof through slot 191 and into position between collars 175. Edge 176 of spring 173 remains free, and presses outwardly on the cable 42 which is wrapped therearound. As shown, the spring 173 is interposed between the wrapped cable 42 and the hub 172 so that the forward tangential movement of cable 42 compresses spring 173. When spring 173 is sufficiently compressed, the drive cable 42 will transmit the cable tangential force to the outer surface of the hub 172 to rotate it. When the pedal arms 38A and 38B are released by the operator, cable 42 will be urged rearwardly by the spring 173 which exerts an outward force and expands against the wrapped drive cable 42. Spring 173 absorbs the extra length of the drive cable 42 to tension the cable 42 to keep cable 42 wrapped about hub 172 and to urge both pedal arms 38A and 38B to a raised position. Cable 42 again may slip about hub 172 without damage when the vehicle is moved rearwardly, because cable 42 is only wrapped thereabout and is not otherwise secured thereto.

A second embodiment of the force transmission assembly 210, as shown in FIGS. 1, 13, 14 and 15 has two independent drive cables 42A and 42B, one cable 42A or 42B being associated with each pedal arm 38A and 38B respectively. Pedal arms 38A and 38B are as shown in Figs. 5 and 6. Rather than having each end of the drive cable terminate in a different pedal as in the single cable drive, each cable of the dual cable drive has one end which is secured to its associated pedal arm and another end which terminates independently of a pedal. As a result, there is no longer a need for a cross-over

pulley 66, shown in FIGS. 9 and 10. In the two cable configuration, each cable 42A or 42B passes from its respective pulleys 60A or 60B and is spirally wrapped around its respective hub 70A or 70B, in the manner shown in FIG. 15. Hubs 70A and 70B again rotate independently of each other, and in the embodiment of FIGS. 1 and.13 are disposed on axle 181 on either side of wheel 46 and rotate about a common axis. As the pedal ends of the drive cables 42A and 42B are cycled back and forth, the other end of each respective drive cable will also move back and forth, and thus a tension must be applied to the non-pedal termination ends of cables 42A and 42B to keep cables 42A and 42B tightly wrapped about hubs 70A and 70B and to return pedals 40A and 40B to a raised position. In one embodiment, the tension is produced by respective springs 113A and 113B. Springs 113A and 113B, may be long, coiled springs running longitudinally through frame 32 of the vehicle, as shown in FIG. 1, or underneath frame 32 as shown in FIG. 14. Springs 113A and 113B are each secured at one end to an anchor 38 on frame 32 adjacent steering assembly 220 and at the other end to a respective cable 42A and 42B. Springs 113A and 113B may be either compression or extension springs, and known means may be provided for adjusting the tension thereof. Cables 42A and 42B- may be sheathed in a conduit 320 (FIG. 1) as they pass from hubs 70A and 703 to their respective springs 113A and 113B to redirect the cables. Conduit 320 is necessary because cables 42A and 42B must exit respective hubs 70A and 70B normal to axle 181 to prevent overlapping thereof. However, springs 113A and 113B are disposed centrally on frame 32 between hubs 70A and 70B and thus, if the cables passed directly thereto, they would form an angle with respect to the axle and rub against wheel 46. Conduit 320 may be composed of nylon

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or any other suitable material. A plurality of pulleys may also be used to perform the function of conduit 320 in a manner known to those skilled in the art.

As shown in FIG. 14, 15, and 17, a stop plate 291 may be provided to prevent over-extension or compression of springs 113A and 113B and to prevent them from becoming wrapped around hubs 70A and 7OB. Plate 291 may be either within frame 32, as shown in FIGS. 15 and 17 or disposed along the underside of frame 32, as shown in FIG. 14, depending upon the location of springs 113A and 113B. Plate 291 has apertures 293A and 293B through which respective cables 42A and 42B pass and which are adapted to engage respective stops 295A and 295B adjacent the respective connections of springs 113A and B to cables 42A and 42B when the spring has been extended a specified distance. Plate 291 also serves to limit pedal travel at the lower end of the pedal arc. Resilient aperture guards 332A and 332B may be provided adjacent respective apertures 293A and 293B to cushion the arresting action of plate 291 and prevent damage to the cables 42A and 42B or the rest of the drive system.

' Reel type spring assemblies 112A and B as shown in FIG. 13 may also be used as an alternative to springs 113A and 113B to tension cable 42A and 42B. Each reel assembly 112A and 1123 is secured to an end of respective cable 42A and 42B, and assemblies 112A and B are secured to frame 32, typically rearwardly of hubs 70A and 70B. Assemblies 112A and 112B may be positioned anywhere close to hubs 70A and 7OB so that the cables exit hubs 70A and 70B normal to axle 181. Reel assemblies 112A and 112B are spring wound and serve to maintain a pulling tension on cables 42A and 42B respectively, winding the cables about a reel. As pedal arms 38A and 38B are pushed downwardly, the force of the operator overcomes the

spring tension on the cables, causing them to unwind from assemblies 112A and 112B respectively to rotate hubs 70A and 70B. Other types of spring assemblies may be used to tension cables 42A and B and the above examples are not intended to be limiting.

A third embodiment of the force transmission assembly is shown in FIG. 14, and in more detail in FIG. 15, wherein a conventional bicycle wheel is employed having a multiratio (e.g., multi-speed) drive hub 80. Hubs 70A and 70B are mounted on an axle 181 independently of and spaced from the drive hub 80. Two cables 42A and 42B are wound thereabout and drive hubs 70A and 70B and axle 181 as previously described for a two cable drive system. A chain 82 or other suitable drive couples a drive sprocket 34 mounted on axle 181 to sprocket 36, which drives hub 80 of rear wheel 46, as shown in FIG. 14. The cable tension springs 113A and 113B are described above and are shown extending within the frame 32, but they may be alternatively housed elsewhere. Springs 113A and 113B are anchored to a wall 88 or any other securing means on or adjacent frame 32, as described.

In each of the previously described embodiments, the hubs 172 and 70A and 70B typically are coupled to an axle 181 of wheel 46 by respective unidirectional clutches 171 (FIG. 16) and 71A and 7IB (FIG. 9). Clutches 171 and 71A and 71B typically are roller clutches, such as Torrington type FC-35 clutches or they may also be a standard ratchet and pawl clutch. Clutches 71A, 71B and 171 selectively provide torque coupling with axle 181 in one direction, such as a clockwise direction in FIG. 9, to provide forward movement of the bicycle, and free rotation when hubs 70A, 70B or 172 are

stationary or rotate backwardly, such as in a counterclockwise direction in Fig. 9.

Spring 173 of FIG. 16, spring 57 of FIG. 5A, assembly 112 of FIG. 13, and springs 113A and 113B of FIG. 1 each maintain tension on the cable 42 to urge the corresponding pedals to return to a raised neutral position when not in use and to prevent the cable from becoming unraveled when the pedals are raised. In the two cable embodiments, the pedal arms are raised into a position so that pulleys 56A are closely adjacent pulley 60A, separated by shock absorber 287, as shown in FIG. 6, or as shown in FIG. 14. In the single cable embodiment, spring 173 need only be strong enough to take up any cable slack when pedal arms 38A and 38B are raised toward frame 32 when not in use, their exact position depending upon the position in which they are left by the operator. In each of the above described embodiments, if the vehicle is moved manually or otherwise in a rearwardly direction, clutches 71A and 71B or 171 (FIG. 9) engage axle 181. However, in such rearward movement, cables 42A and 423 slip about hubs 70A and 70B or element 172, since the cable is only wrapped thereabout and not attached thereto, and thus the vehicle may be moved rearwardly without damage. When a driving force is applied to the pedal arms, the cable is- prevented from slipping about hubs 70A and 70B and element 172 by the anchoring of one end of the cable and the spring biasing of the other end of the cable, as described. Pedal travel at the lower end of the pedal arc is limited either by stop plate 291 (FIG. 17) for the two cable embodiments or by pulley housings 62A and 62B for the single cable embodiments, while pedal travel at the upper end of the pedal arc is limited by pulley housings 62A and 62B in all cases.

If desired, a spiral, outwardly extending lip (not shown) may be provided about hubs 70A and 70B and on hub 172 defining a spiral track to properly align cable 42 as it is wrapped thereabout and to prevent cable 42 from abrading with itself.

The vehicle of this invention may be partially disassembled for transport onto a mass transit vehicle or elsewhere. The steering assembly 220 may be disassembled at the front pivot 89. When disassembled, the vehicle is compact and extends in a vertical direction, taking up very little floor space. It may be transported in any convenient manner and may be carried anywhere, including on a mass transit vehicle. A crutch tip 110 (FIGS. 13 and 14) may be provided on each extension .of frame 32 beyond wheel 46 to allow the vehicle to rest in an upright position on the floor. Tips 110 are sufficiently spaced from wheel 46 to allow a person's feet to reside between a floor and wheel 46. A typical vehicle when folded has dimensions of 47" by 12" by 12". With reference to FIGS. 11 and 12, steering assembly 220 and its manner of connection to frame 32 will be described. Assembly 220 includes steering supports 34A and 34B which are disposed in either side of wheel 36 and which are connected to the axle of wheel 36 at one end thereof in a manner known to those skilled in the art. A tubular housing 90 is secured to the end of frame 32 transversely thereof and is the linkage by which frame 32 is secured to steering assembly 220. When assembled, housing 90 is axially captured between cross- supports 98 and 99 which extend parallel to one another between vertical steering supports 34A and 34B. Lips 127 on supports 98 and 99 restrain housing 90 laterally and guide housing 90 when it is inserted into place between supports 98 and 99. Lips 127 may have a generally

semi-circular configuration, with the open portion facing frame 32. Housing 90 is essentially perpendicular to cross-supports 98 and 99 in the assembled position shown in FIG. 11. A plunger 104 in support 98 has a pin 100 which is secured thereto and which extends downwardly therefrom into housing 90 through a tube 103 which extends upwardly from support 98 and is secured thereto. Plunger 104 and pin 100 are spring biased downwardly by compression spring 102 so that plunger 104 is urged into contact with housing 117 disposed on an upper rim of tube 103 which acts as a stop. Pin 100 and plunger 104 are rotatable with respect to tube 103, and pin 100 has a projection 105 which extends radially outwardly therefrom and which is adapted to pass vertically through a slot in housing 117. Plunger 104 may be locked into a raised position using projection 105 by raising plunger 104 and pin 100 upwardly until projection 105 is above housing 117- and then rotating plunger 104 until projection 105 is not aligned with its slot and overlies housing 117. When plunger 104 is lowered by passing projection 105 through its slot, a lower end of pin 100 is urged into contact with an upper end of a pin 92 extending axially through housing 90. Pins 100 and 92 meet within channel 121 formed within housing 90. ^' A lower end of pin 92 extends beyond housing 90 and into a channel 123 formed in support 99. Pin 92 is biased upwardly by spring 91 acting between bearing surface 133 and plate 131 secured to pin 92. The lower end of pin 92 is urged into channel 123 in an assembled condition by pin 100 which is urged downwardly by spring 102.

To disassemble assembly 220, plunger 104 is raised upwardly until pin 100 is raised out of channel 121 thus permitting spring 91 to raise pin 92 out of channel 123. Plunger 104 is then locked into a raised position by

rotation thereof, causing projection 105 to move out of alignment with its slot and to overlie the upper rim of tube 103. Housing 90 then may be withdrawn from supports 93 and 99. The procedure is reversed when the vehicle is to be assembled, lips 127 guiding housing 90 into the proper alignment.

The handlebars 31A and 31B are adjustable to compact the vehicle for storage or carrying. The handlebar retainer 43 is shown in relation to the entire steering assembly 220 in FIG. 12. Each handlebar 31A and 31B is concentric with and slidably disposed with respect to its associated steering support 34A and 34B. Handlebars 31A and 31B preferably telescope into supports 34A and 34B respectively. Without the retainer 43, handlebars 31A and 313 would be free to rotate about and slide along the axis of the supports 34A and 343 until secured, with the result being delay and difficulty in properly and uniformly positioning the handlebars when assembling the vehicle for riding. The handlebar retainer 43 comprises two cylinders 47A, 47B, which are held in fixed relation by spacer bar 48 and which are concentric with and surround respective handlebars 31A and 31B. Spacer bar 48 also maintains handlebars 31A and 31B in the desired alignment with respect to one another. An annular ring 142 is disposed within each cylinder 47A and 47B and secured to each handlebar 31A, 31B, around the exterior thereof. Each ring 142 is concentric with its associated handlebar. An upper annular ring 141 surrounds each handlebar 31A and 31B, and each ring 141 is secured to a respective cylinder 47A and 47B. Ring

141 has a gap 145 which is bounded by two axially aligned shoulders 388 and 389. Shoulders 388 and 389 subtend an angle which is generally equal to the desired permissible angular rotation or splay of the handlebars 31A and 31B,

which is typically 60°. Each ring 142 has an axially extending detent 146 residing in space 145. Detents 146 abut shoulders 388 and 389 upon rotation of handlebars 31A and 31B to limit the rotation thereof with respect to cylinders 47A and 47B and to provide an accurate means of adjusting the splay of the handlebars. Shoulders 388 serve to limit the outward splay of handlebars 31A and 31B, and shoulders 389 limit the inward splay thereof. It should be noted that shoulders 389 are optional. An annular ring 144 is disposed below ring 142 within each cylinder 47A and 473 and is secured thereto to capture ring 142 between it and ring 141 and to retain cylinders 47A and 47B securely in place on handlebars 31A and 313. A clamp 298 disposed on the upper end of each support 34A and 34B where handlebars 31A and 3IB join their respective supports and locks handlebars into a desired splayed position and locks the handlebars into a desired extended position with respect to the steering supports. Clamps 298 may be any common. clamp known to those skilled in the art, including a push button or quick release clamp. A spring biased release button on handlebars 31A and 313 in combination with a series of spaced, axially aligned mating holes (not shown) in supports 34A and 34B could be used to axially align the height of handlebars 31A. and 31B and to position the outer splay thereof instead of clamp 298 and rings 141, 142 and 144.

In operation, when the handlebars 31A and 31B are to be adjusted for normal vehicle operation, the handlebars are pulled upwardly in concert along supports 34 by grasping spacer bar 48 until the desired extended position or height (with respect to the particular operator) is attained. Then the handlebars are angularly splayed outwardly as shown in FIG. 12, preferably until

the detents 146 reach their angular limit, abutting shoulders 388. The position of the handlebars 31A and 31B are then secured by tightening clamps 298. When the vehicle is to be compacted for storage or carrying, clamps 298 are released, and handlebars 31A and 31B are rotated about the axis of the supports 34 inwardly until they are substantially parallel to the plane of the wheel 36 and until detents 146 abut shoulders 389. The height of the disassembled assembly may be reduced by sliding the handlebars downwardly along the supports 34 toward the wheel 36.

Pedal arms 38A and 383 each have two positions, that is, each may be rotated into an operating position or it may be folded for storage when the bicycle is disassembled. The operating and storage positions of each pedal arm are shown in FIGS. 3 and 4 respectively. Although the description of FIGS. 3 and 4 refers to pedal arm 38A only, it is to be understood that pedal arm 38B is similar to pedal arm 38A. The pedal 40A is rotatably disposed on shaft 41A which is rigidly affixed to arm 38A. Pedal 40A rotates with respect to shaft 41A to allow pedal 40A to remain essentially horizontal during the up and down movement of arm 38A. Arm 38A is shown in cross-section in FIGS. 3 and 4, and is held in position relative to the frame 32- by pivot 37. Arm 38A has two slots 39A and 39B disposed radially opposite one another. Slots 39A and 39B each form an elongated groove which extends along the circumference of the tubing and which encompasses an arc approximately equal to 90°. One end 137 of pivot 37 extends through slot 39B to frame 32, while the other end 138 of pivot 37 extends through slot 39A away from frame 32. Secured to end 138 is a bolt 136 which has a diameter greater than that of slot 39A and retains arm 38A in place by capturing a wall thereof

adjacent slot 39A between it and an enlarged portion of pivot 37. This extended groove permits pedal arm 38A and the attached pedal to be rotated an angle equal to that encompassed by the slots 39A and 39B from a horizontal riding or operating position to a vertical or storage position. This operation is possible because the force applied to the pedals 40A and 40B and the pedal arms 38A and 38B during operation thereof drives pivot 37 against the upper end of slot 39A and the lower end of slot 39B, as shown in FIG. 3.

If a seat 52 is provided, it is secured to support 51 by means of a clamp 397 (FIG. 2) or release button (not shown) . Seat 52 may be separated from frame 32 by releasing clamp 397 or by depressing the release button. The seat 52 is also adjusted in height on support 51 in the same manne .

With respect to materials, cable 42 may be composed of any suitable flexible material such as steel, nylon, rubber, twine, or cord. Cable 42 may also be a chain formed of any material. The steering assembly and frame may be composed of any suitable material, such as steel, aluminum or plastic.

The vehicle may be provided with front and/or rear brakes which are operable by hand levers 356 (FIGS. 1 and 2) secured to respective-handle bars 31A and 31B. These brakes function in a manner well known to those skilled in the art. Wheels 36 and 46 may be mounted in a manner well known in the art, and fenders 382 and 384 may be provided for wheels 36 and 46 respectively. Figs. 18-22 illustrate a further embodiment of the present invention. Figs. 18-22 illustrate an embodiment of the invention that improves the match of rider strength to vehicle mechanical advantage. It also employs a twin-tube construction that enables the seat

assembly to be collapsed a greater distance and houses the cables throughout greater portions of their lengths.

In this embodiment, the coupling of the cable to the drive wheel is the same as that employed in the embodiment of Fig. 1. The embodiment of Figs. 18-22 depart from the previous embodiments in that the cable is much more completely enclosed, and different mechanisms are employed for collapsing the seat and the handlebars. Furthermore, the drive system of the vehicle of Figs. 18- 22 more nearly matches the relationship between available force and leg position characterizes the average person. In Fig. 18, the vehicle is indicated generally by reference numeral 400 and includes a frame 402 that differs somewhat from the frames of the embodiments of Figs. 1 and 2. Frame 402 includes a tubular seat support 404 that is oriented at a small angle to the rear of the vertical. An upper frame arm 406, as Fig. 19 shows, includes a pair of tubular members 406A and 4063 that join in a U-shaped portion 407 that is welded or otherwise suitably joined to seat support 404.

A lower frame arm 408 is also joined to seat support 404, and Fig. 19 shows that it also includes a pair of tubular members 408A and 408B. Upper and lower frame arms 406 and 408 join in a drive-wheel mounting portion of the frame that includes a hub cover plate 410. A drive wheel 411 is rotatably mounted on the drive-wheel mounting portion for driving by cables in the manner disclosed in connection with the embodiment of Fig. 1. Frame 402 further includes a single horizontal support member 412 that extends forward from seat support 404 to a housing portion 413 on which a steering mechanism 414 is pivotally mounted. Steering mechanism 414 is similar to that illustrated in Fig. 11. Lower frame arm 408 is also joined to housing portion 413.

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The lower portion of steering mechanism 414 will not be described in any detail, because it is similar to that disclosed in connection with Fig. 11 and related drawings. As Fig. 13 shows, the steering mechanism includes a rotatably mounted front wheel 416, and the steering mechanism may be removed if desired by manipulation of plunger 418, which is similar to plunger 104 of Fig. 11.

Like the embodiment disclosed above, that of Fig. 18 includes a pair of pedal arms 420A and 4203 that are pivotably mounted to frame 402 at their forward ends by means of a pivot pin 422. At the rear end of each pedal arm 420 is provided a pedal 424 shown in phantom in Figs. 18 and 19. In this embodiment, a cable 426A is trained into the interior passage of pedal arm 420A and attached to pivot pin 422. The attachment of a cable to pivot pin 422 is a safety measure. The primary attachment of cable 426A to pedal arm 420A is provided by the pinching of cable 426A when pedal 424A is threadedly mounted in pedal arm 420A. When pedal 424A is tightened into place, it traps cable 426A against pedal arm 420A. This arrangement allows the effective length of cable 426A to be adjusted by the loosening of pedal 424A, the further insertion or withdrawing of cable 426A into or out of pedal arm 420A, and the subsequent retightening of pedal 424A.

Like the previous embodiments, that of Fig. 18 includes a pulley 428A that is used in defining the path along which cable 426 is to travel. Cable 428A is rotatably mounted in a pulley-mounting housing 430A that depends from tubular member 406A of upper frame arm 406A. An opening is provided in the lower surface of tubular member 406A, and this opening receives a portion of

pulley 428A so that cable 426A can be trained around pulley 428A to extend along the interior passage 431A of tubular member 406A. Cable 426A thus enters tubular member 406A adjacent seat support 406, and it extends down the interior and out an opening at the drive-wheel ' mounting portion of the frame to be coupled to a hub 432A in the manner described in connection with the embodiment of Fig. 1. From hub 432A, cable 426A extends through an opening in tubular member 408A into its interior and terminates in a stop member 434A. A spring 436A is mounted in tubular member 408A by a mounting pin 438A and is connected to stop 434A through an eye provided in it. Spring 436A thereby tensions cable 426A. A resilient stop 440A is provided in the interior of tubular member 408A to engage stop member 434A and thus limit the travel of cable 426 and pedal 424. Stop 440 is. resiliently deformable and thus absorbs the shock that can be encountered at the end of pedal travel.

The elements designated in Fig. 18 by reference numerals with the suffix A are duplicated on the left side of the bicycle by similar elements identified in Figs. 19-22 by reference numerals including the suffix B.

In light of the description so far, it can be seen that both cables 426 (i.e., both the cable 426A and cable 426B) are enclosed along" almost all of their lengths, although those portions between pedals 424 and pulleys 423 become more exposed as pedals 424 travel downward. This is an advantage because it makes it possible to reduce the likelihood that the cable will become fouled, and it also reduces the incidence of soiled clothing resulting from contact with oiled steel cables, for instance. The incidence of soiled clothing can be further reduced by making the portions of cables 426 that can be exposed between pulleys 428 and pedals 424 of a

material, such as an ara id fiber, that does not require oiling and is thus less likely to soil the clothing of the rider.

Furthermore, although the twin-tube arrangement for housing the drive cables has been illustrated in connection with a two-cable drive system, it is evident that the twin-tube upper support arm could equally well be employed to house the cable in a single-cable drive system of the type described in connection with Fig. 2. Bicycle 400 is propelled in a manner similar to that in which the vehicles of Figs. 1 and 2 are. The rider uses his legs to cause reciprocation of one or the other or both of pedals 424. Downward motion of one of the pedals 424 causes cable 426 to be pulled forward in a tubular member 406 and backward in a tubular member 408. The travel of a cable 426 along this path causes rotation of its associated hub 432 and drive wheel 411. Eventually, its associated stop member 434 comes into contact with its stop 440, thereby terminating travel of pedal 424 in a stop position. The associated hub 432 also stops, but, by virtue of the coupling described above, drive wheel 411 continues rotation. ^" The rider then releases the force on the pedal, and the associated spring 436 therefore retracts the cable to return the pedal to a rest position beyond which the spring cannot pull the pedal.

When pedal 424A, for instance, is in its rest position, the tension on cable 426A is low enough so that hub 432A can be rotated independently of the movement of cable 426A. Such independent motion is desirable in instances in which the vehicle is to be backed because movement of the pedals in response to backward rotation of the drive wheel, which is acceptable in conventional bicycles, cannot be permitted in a vehicle of the type

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illustrated in the drawings in which the pedals merely reciprocate between two fixed points and do not travel in an endless path.

One of the advantages of the arrangement of Fig. 18 follows from the relative positions of pedals 424 and pulleys 428. In the rest position illustrated in Fig. 18, cable 426A extends from pedal 424A to pulley 428A at a relatively large angle with the tangent to the arcuate path of pedal travel. Reflection reveals that this relative positioning results in a considerable mechanical advantage, that is, in a ratio of pedal travel to cable travel that is considerably greater than 1. As pedal 424 moves downward, however, this mechanical advantage is reduced so that the ratio of pedal travel to cable travel approaches unity. Consequently, the mechanical advantage enjoyed by the rider is reduced as he extends his leg during pedaling.

This arrangement is advantageous because a plot of mechanical advantage as a function of pedal travel complements a plot of available force as a function of leg extension. At the top of pedal travel, where the rider's leg is more flexed, he is able to exert a relatively low force, but he is afforded a mechanical advantage by the relative positioning of the pedal and pulley. As he extends his leg, the amount of force that he can apply increases, but the mechanical advantage provided by the positioning of the pedal and pulley decreases so that a relatively greater amount of drive- wheel rotation results from a given amount of pedal travel.

Studies of the relationship between available force and leg position reveal that force is a complicated function not only of the amount by which the leg is extended but also of the angle of the extension. In

general, it can be said that the force available is relatively low when the leg is greatly flexed and increases as the leg extension increases, although the available force does fall off again when the leg is fully extended. In view of this, general trend, it is advantageous for the mechanical advantage to generally decrease so the pedal moves toward its stop position.

The seat assembly of the embodiment of Fig. 18 differs from that of the embodiments of Figs. 1 and 2. In bicycle 400, seat support 404 is a tubular member with an axial passage extending its entire length to provide openings at both ends, the upper one of which receives the lower tubular member 442 of a seat pedestal that includes member 442 and a small-diameter tubular member 444 that fits telescopically into the interior passage of member 442. A conventional saddle member 445 is provided at the upper end of inner pedestal member 444. The axial position of pedestal members 444 with respect to member 442 is fixed by means of an appropriate fastening element 446. The axial position of outer pedestal member 442 with respect to seat support 404 can be adjusted by means of a similar fastening means evidenced in Fig. 13 by its lever 448.

In the particular embodiment of Fig. 18, a window 450 is provided near the. upper end of outer pedestal member 442 so that height indicia 451 scribed on inner pedestal member 444 can be viewed to facilitate quick adjustment of seat height. In the case illustrated in Fig. 18, the height indicia represent inseam lengths so that rental bicycles, for instance, can be quickly adjusted for renters who know their inseam lengths.

Adjustment of the seat to match the size of the rider is accomplished primarily through the use of fastener 446. For collapsing of the seat, on the other

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hand, fastener 448 is employed in conjunction with fastener 446. By releasing both of these fasteners, the seat can be collapsed to the position illustrated, in Fig. 22, where both the inner pedestal portion 444 and the outer pedestal portion 442 are seen to extend out the bottom of seat support 404. This type of collapsing is possible because arms 406 and 408 are made of two tubular members so that seat support 404 can extend between them, and because seat support 404 has an opening at its lower end. As a result, seat support 404 does not have to be as long as the pedestal portion of the seat assembly. The advantage of this arrangement can be seen by comparison of Figs. 18 and 22. Those figures show that seat support 404 does not extend below lower arm 408 and is thus spaced a comfortable distance from the ground, but the space between lower arm 408 and the ground plane is available for use in collapsing the seat assembly.

The steering mechanism 414 is best understood by simultaneous reference to Figs. 18 and 20. The lower portion of steering mechanism 414 will not be described in detail, because it is substantially similar to the lower portion of the steering mechanism illustrated in Fig. 11 and related drawings. Front wheel 416 is rotatably mounted on fork arms 452A and 452B. Arms 452A and 452B are in turn secured in supports 453, which are similar in function to supports 98 and 99 of Fig. 11. Supports 453 are pivotally and removably mounted on a housing portion 413 of frame 402. Housing 413 is similar to housing 90 of Fig. 11 and houses a similar mechanism so that the steering mechanism can be removed from frame 402 by manipulation of knob 413.

Fork arms 452A and 452B provide interior passages in which elongated telescope members 456A and 456B are secured by fasteners 457A and 457B. Telescope members

456A and 456B provide offset portions 458A and 458B, respectively, at their upper ends. Offset portions 458A and 458B extend forward from telescope members 456A and 456B to support handlebar sleeves 460A and 456B. Handlebar sleeves 460A and 460B receive L-shaped handlebars 462A and 462B, respectively, and secure them in position in a manner that will be described by reference to Fig. 21.

As Fig. 21 shows, handlebar 462A extends through handlebar sleeve 460A to protrude just slightly below the lower end of sleeve 460A. The protruding end of handlebar 462A is provided with a plug 464A, and the upper end of sleeve 460A is provided with a cap 466A threadedly received on the upper end of sleeve 460A. The interior surface of sleeve 460A is tapered outward at both ends and receives tapered annular shims 468A between these interior surfaces and the adjacent exterior surface of handlebar 462A. The upper one of shims 468A is lightly wedged into place by cap 466A, while the lower one of shims 468A is lightly wedged into place by cap 464A. The use of the shims is not required, but they may be desirable to take up manufacturing tolerances between sleeves 460 and handlebars 462. The shims are wedged tightly enough so that their is no play in the handlebars, but they are not wedged so tightly that collapsing of the handlebars is difficult. Sleeve 460B and related parts are arranged similarly.

Handlebar sleeves 460A and 460B are joined by a cylindrical cross piece 470 that is provided with an axial bore 472 extending the entire length of the cross piece. Extending radially outward from bore 472 is a slot 473A that extends only along a small portion of the length of cross piece 470.

An axially extending portion 474A of an L-shaped pin is received in axial bore 472 and extends into a hole 475A in handlebar 462A to secure it in the proper axial and angular positions. A radial portion 476A of the L-shaped pin extends outward through the radially • extending slot 473.

A horizontal sleeve 480 is rotatably mounted on cross piece 470 and includes a slot 482B in the shape of a helix segment through which the radially extending portion 476B of a second L-shaped pin is received. A second slot (not shown in Fig. 21) is formed in sleeve 480 complementary to slot 482B in which radial portion 476A of the left L-shaped pin is received. A coil spring 478 is received in axial bore 472 and biases both of the L-shaped pins into the holes 475 in handlebars 462.

Sleeve 480 can be rotated manually by the user, and this rotation causes the surfaces defining slots 482 to bear against the radial portions 476 of the L-shaped pins and slide the pins inward so that the axial portions 474 of the L-shaped pins are retracted from the holes 475.

This permits the rider to rotate handlebars 462 and slide them axially.

Steering assembly 414 can thus be collapsed to the position illustrated in Fig. 22 by rotating sleeve 480 to disengage the L-shaped pin and then rotating handlebars 462 and sliding them downward. Fastening means 457 (Fig. 13) is then loosened to permit telescoping members 456 to slide farther into the interior of fork arms 452. It can be seen that the result would be the handlebar position illustrated in Fig. 22. Removal of the steering assembly, if desired, could be accomplished in the manner described in connection with Fig. 11. Fig. 22 also shows that the pedals could be arranged to be pivoted upward in

the manner previously described for further compactness of the collapsed vehicle.

Rotatable sleeve 480 can rotate freely on cross piece 470, and spring 478 accordingly tends to cause radially extending pin portions 476A and 4763 to urge sleeve 480 toward the angular position shown in Fig. 21. Accordingly, when the handlebars 462A and 462B are to be retracted back into their normal positions, the operator merely slides the handlebars 462 up to the proper position and then rotates them until L-shaped pins snap into place in recesses 475 and handlebars 462.

A particular advantage of the arrangement of Figs. 18-22 is the matching of the mechanical advantage is a function of pedal travel to the rider's strength as a function of leg extension. This matching is achieved in the embodiment of Figs. 18-22 by the relationship of the pedal path to the position of the pulley 428 that is used to define the cable path. Another way to cause the mechanical advantage to vary as a function of pedal travel is illustrated in Fig. 23, which also illustrates a further alternate arrangement for tensioning the cable.

Fig. 23 is a detail of an alternate means for coupling the cable to the drive wheel. In Fig. 23, a central portion 502 of the drive wheel is shown with a spoke 504 extending radially from it. The drive wheel is mounted for rotation by means of bearings 506 on an axle 508. The central portion 502 of the wheel is coupled by means of a conventional unidirectional clutch 510 to a hub 512 so that the wheel can rotate forward with respect

I to ^' hub 512. Forward rotation of hub 512, however, requires forward rotation of wheel 502.

Hub 512 provides a frustoconical outer surface portion having an engagement coating 514 that faces a complementarily shaped surface of a flexible sleeve 516.

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Sleeve 516 is provided with helical grooves in which a cable 518 is received. The general shape of sleeve 516, together with the relationship of pedal travel to cable travel, determines the mechanical-advantage curve, and tension on cable 518 deforms sleeve 516 to a greater or lesser degree to determine the amount of friction between sleeve 516 and engagement surface 514 of hub 512.

Sleeve 516 is joined by an appropriate bonding medium 520 to an annular reel housing 522 that is generally U-shaped in cross section. Reel housing 522 is mounted on hub 512 by bearings 524. A spirally wound spring 528 is secured at one end to axle 503 and at the other end to the radially inner surface of reel housing 522. Cable 518 is secured to reel housing 522 at a lip 530 provided on its outer surface, and spring 528 angularly biases reel housing 522 so that cable 518 is in turn biased toward the rest position of the pedal to which it is attached. Accordingly, spiral spring 528 performs the biasing function that is performed in the Fig. 18 embodiment by spring 436A or 436B.

When the pedal to which cable 518 is attached is in its rest position, spring 528 is initially relatively relaxed. Accordingly, the tension on cable 518 is low, and flexible sleeve 516 is not squeezed by cable 518 into engagement with surface 514 of hub 512. If the bicycle is being backed with the pedals in the rest position, clutch 510, which does not permit rearward rotation of wheel 502 with respect to hub 512, causes rearward rotation of hub 512. Since there is no significant frictional engagement between sleeve 516 and engagement surface 514, however, the bias force from spring 528 causes sleeve 516 to remain fixed with respect to axle 508. Accordingly, although hub 512 is rotating with respect to cable 518, cable 518 does not slide along

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sleeve 516. Thus, the relative angular positions of the spirally wound cable 518 and sleeve 516 remain the same.

When the rider applies a downward force to the pedal to which cable 518 is attached, sleeve 516 begins to rotate against the bias- of spring 528. The force applied by springs of the general type exemplified by spring 528 is relatively low in the rest position of the spring. The force quickly increases to a plateau with initial rotation but force increases very little with further rotation. After a short amount of rotation of sleeve 516, the tension on cable 518 is enough to bring sleeve 516 into significant frictional engagement with engagement surface 514 of hub 512. Hub 512 is thus caused to rotate forward, and this forward motion is coupled to wheel 502 by unidirectional clutch 510.

It will be appreciated that cable 518 is initially drawn from sleeve 516 at the axially inward end of the surface, which has the highest diameter. As a consequence, the amount of rotation of hub 512 for a given amount of cable travel is relatively low. In other words, the mechanical advantage experienced by the rider is relatively high. As pedal travel continues, the diameter of sleeve 516 at the axial position from which cable 518 is being drawn decreases, thereby decreasing the mechanical advantage- but increasing the amount of wheel rotation for a given amount of pedal travel. This decrease in mechanical advantage generally matches the increase the force that the rider can apply, so there is an efficient matching of the force to the load. When the pedal reaches its stop position, the rider raises his foot, and spring 528 causes reel 522 to reverse its rotation. Reel 522 thereby rewinds cable 518 and returns the pedal to its stop position. Since the travel of cable 518 is always accompanied by rotation of

sleeve 516, the effective diameter of sleeve 516 for a given position of pedal travel is always the same. Therefore, the relationship between pedal position and mechanical advantage is preserved. The embodiments of the present invention illustrated in the drawings provide the advantages of the reciprocating-pedal drives previously employed but avoid the previous disadvantage that backing of the vehicle was not possible without raising the drive wheel. It is clear that the general teaching employed here of permitting independent motion of the hub when the pedal is in its rest position but not when it is in its drive position can be carried out in a number of forms not illustrated in the drawings. For instance, the cable used to carry out the teachings of the present invention does not have to be a smooth, unitary metal cable. As was mentioned above, it may be desirable to employ organic materials for that portion of the cable that is most often exposed. Furthermore, it can be seen that, for the purposes of the present teachings, the term

"cable" can even include chains. Thus, the hub could be provided as a sprocket for engagement by a chain, although the chain would have to include some provision, such as the omission of chain links or the inclusion of some type of disengaging- surface, by which independent motion of the sprocket with respect to the chain would be permitted in the rest position. As the chain travels from the rest position, links would come into engagement with the sprocket to cause the necessary driving. Additionally, in those versions of the vehicle in which the mechanical advantage is to be matched to the driver's strength as a function of leg extension, all that is necessary is that the amount of hub rotation vary as a function of pedal travel. It is not necessary that

this be achieved by the relative positioning of the pedal path and the pulley or other path-defining element. As was illustrated in the description accompanying Fig. 23, an appropriately contoured hub can be used to achieve this effect. A simpler version could be achieved by substituting a contoured pulley for, say, pulleys 428 of Fig. 13 and then spirally wrapping the cable around the contoured pulley to vary the amount of cable travel at the hub per unit pedal travel. It is thus apparent that the present invention provides teaching of broad applicability that represents a significant advance in the art of operator-powered- vehicle construction and propulsion. While using a reciprocating drive that is particularly well suited to collapsible vehicles, it permits rearward motion, which was not previously possible with such reciprocating drives. Additionally, the illustrated vehicles can be collapsed easily into a compact form.

Although the present invention was described with regard to a bicycle, it is equally suited to a tricycle or any other operator powered vehicle. While the above discussion describes the present invention according to one embodiment, it is understood that this description is made only by way of example and not intended to limit the scope of the invention. -Other modifications and embodiments are within the scope of the invention as may be provided by those skilled in the art.