Patent Publication Number: US-7591765-B2

Title: Free wheel clutch mechanism for bicycle drive train

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 10/093,326 entitled “Free Wheel Clutch Mechanism for Bicycle Drive Train,” filed on Mar. 6, 2002, which is a continuation-in-part of application Ser. No. 09/803,630 entitled “Free Wheel Clutch Mechanism for Bicycle Drive Train,” filed Mar. 9, 2001; which is a continuation-in-part application of application Ser. No. 09/379,560, entitled “Free Wheel Clutch Mechanism for Bicycle Drive Train” filed Aug. 23, 1999; now U.S. Pat. No. 6,641,507; which is a continuation of application Ser. No. 08/919,695, entitled “Free Wheel Clutch Mechanism for Bicycle Drive Train” filed Aug. 28, 1997, now U.S. Pat. No. 5,961,424; which is a non-provisional utility application claiming priority to provisional application Ser. No. 60/038,726 entitled “Free Wheel Clutch Mechanism for Bicycle Drive Train,” filed Feb. 18, 1997, which are each hereby incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION  
     This invention relates generally to free wheeling devices, and more particularly to a free wheel clutch mechanism useful with crank operated exercise bicycles employing an inertia flywheel. 
     BACKGROUND 
     The benefit of exercising on a direct drive exercise bicycle is well known. Direct drive exercise bicycles typically utilize a high-inertia flywheel driven by a fixed-gear drive train. The flywheel is driven by the rider up to relatively high revolutions per minute (rpm). Because of the direct drive feature, the drive train must rotate at a fixed ratio of rpm as compared to the flywheel based on the gear ratio. One benefit of the direct drive exercise bicycle is that the direct drive gear train provides “pedal-through assistance” for the rider. The “pedal-through” feature assists the rider by pushing the pedal through the top and bottom dead center pedal positions to help make the transition smooth and efficient. Other benefits are derived from the direct drive interaction between the inertia flywheel and the crank arms to which the rider&#39;s feet are attached. The inertia flywheel provides a smooth, non-jerky pedaling rhythm which provides an efficient and rigorous exercise for the rider, especially at relatively high rpms, such as 60 to 100 rpm. 
     In the application of this invention to an inertia flywheel exercise bicycle, positive drive is required to rotate the inertia wheel in order to overcome regulated retardation torque applied by brake means used to provide resistance against which the rider/operator works. The inertia wheel provides means for continued drive train (wheel to crank to leg) movements during those periods when the crank is in top dead center or bottom dead center positions, where the rider&#39;s legs are somewhat weaker in providing rotary motion to the activating crank arms. The flywheel affords smooth and steady operation for the rider. 
     The direct drive relationship between the flywheel and the drive train is also a drawback of exercising on this type of bicycle. The direct drive relationship is inconvenient when the rider wishes to quickly stop the pedals, or loses the pedaling rhythm required to keep up with the rotating flywheel. In the usual flywheel exerciser employing such a direct drive relationship, it is necessary for the rider/operator to gradually decrease his cranking rate in order to slow down the inertia wheel. The rider cannot suddenly stop pedaling inasmuch as the inertia flywheel continues to drive the crank arms. 
     Of similar importance is the desirability of providing pedal assist to the rider/operator&#39;s legs when cranking at a speed slower than that necessary to positively drive the flywheel, and providing for a gradual reengagement and lockup between the pedal actuated drive shaft and the free wheeling flywheel in order to avoid abrupt impact when reengaging the moving flywheel. 
     It is with these issues in mind that the present invention was developed. 
     SUMMARY OF THE INVENTION 
     The present invention in general terms concerns a clutch mechanism for use on an exercise bicycle, and consequently, the present invention recognizes that it is desirable to have a free wheeling mechanism for an exerciser of the inertia flywheel type which provides means for selectively disengaging the flywheel from the drive means. The clutch mechanism allows for the beneficial direct-drive connection between the drive train and the flywheel, and also allows the drive train and flywheel to move independently from one another, or “break free”, when a sufficient force is applied to the drive train or the flywheel. 
     In general, the invention is an exercise bicycle including a frame having a seat and handlebars, a high-inertia flywheel having a hub at a center of rotation, the flywheel being rotatably supported on the frame at the hub, and a drive train including a drive sprocket, a crank arm attached to and extending from the drive sprocket, and a pedal attached to the crank arm, the drive train being rotatably supported by the frame. The drive train also includes a slave sprocket fixed to the flywheel at the hub, with the drive and slave sprockets connected in a direct-drive relationship, the drive train driveable in a forward and rearward directions to cause the flywheel to rotate. A clutch mechanism is positioned in engagement with the slave sprocket and the hub to create a frictional engagement between the sprocket and the hub, and to establish a break-free force. When the drive train is actuated in the forward direction, the slave sprocket and the hub move together under a mechanical engagement, and when the drive train is actuated in the rearward direction under the influence of a force greater than the break-free force, the clutch mechanism slips between the slave sprocket and the hub, allowing the slave sprocket and the flywheel to move independently of one another. There is no mechanical engagement between the sprocket and the hub in the rearward direction as there is in the forward direction, established by the one-way bearing. 
     More specifically, the slave sprocket defines a sprocket collar mounted on the hub and also includes an engagement collar. A one-way bearing is mounted between the sprocket collar and the hub to allow the sprocket collar to drive the hub when the sprocket collar is driven in a forward direction, and to allow the sprocket collar to spin independently of the hub when the sprocket collar is driven in the rearward direction. An engagement flange fixedly mounted on the hub corresponds to the engagement collar, and compression means are mounted on the flywheel to bias the flange and the collar towards one another. A clutch material member is positioned between the engagement flange and the collar, and is clamped therebetween by the compression means to cause the engagement flange to move in conjunction with the sprocket collar. The engagement creates a break-free force required to cause the sprocket collar to move independently of the engagement flange. When the drive train is actuated in the forward direction, the sprocket collar and the engagement flange move together, and when the drive train is actuated in the rearward direction and overcomes the break-free force, the engagement flange slips with respect to the collar, allowing the sprocket collar and the flywheel to move independently of one another. 
     In another embodiment, the slave sprocket defines a sprocket collar mounted on the hub and defines an inner and outer engagement collars. A one-way bearing is mounted between the sprocket collar and the hub to allow the sprocket collar to drive the hub when the sprocket collar is driven in a forward direction, and to allow the sprocket collar to spin freely on the hub when the sprocket collar is driven in the rearward direction. An inner engagement flange is fixedly mounted on the hub corresponding to the inner engagement collar, and an outer engagement flange is fixedly mounted on the hub corresponding to the outer engagement collar. Compression means are mounted on the flywheel to bias the inner flange and the inner collar towards one another, and to bias the outer flange and the outer collar towards one another. A clutch material member is positioned between the outer engagement flange and the outer collar, and between the inner engagement flange and the inner collar, and clamped therebetween by the compression means to cause the inner and outer engagement flanges to move in conjunction with the sprocket collar. The engagement creates a break-free force required to cause the sprocket collar to move independently of inner and outer engagement flanges. When the drive train is actuated in the forward direction, the sprocket collar and the inner and outer flanges move together, and when the drive train is actuated in the rearward direction and overcomes the break-free force, the inner and outer engagement flanges slip with respect to the inner and outer collars, allowing the sprocket collar and the flywheel to move independently of one another. There are other embodiments of the invention disclosed which perform the same function with very similar structure. 
     Another embodiment of the invention includes a frame with a high-inertia flywheel having an axle and associated axle housing rotatably supported on the frame. A sprocket is coupled to the flywheel. Typically, a chain or belt is connected between the sprocket and a second drive sprocket associated with the pedals. A user pedaling the device thus drives the flywheel by pedaling. To provide a break free force between the flywheel and the sprocket, a clutch according to another aspect of the invention is operably connected between the flywheel and the sprocket to engage the sprocket with the flywheel with the break-free force. When the user is pedaling the device, the flywheel will oftentimes obtain a high level of inertia. In addition, the user will oftentimes use some form of toe clip or clipless pedals to secure their shoes securely to the pedals. The clutch allows the user to disengage themselves from the high inertia rotation of the flywheel without disengaging their shoes from the pedals. 
     In one example, the clutch includes a one way bearing circumferentially mounted on the axle housing. The sprocket is mounted on the axle housing and in engagement with the one way bearing. A clutch plate is operably associated with the sprocket, and a spring of some type is compressed between the clutch plate and the flywheel to engage the sprocket to the flywheel with the break-free force. One embodiment of the cutch plate, such as a clutch plate forming a ring shape, is circumferentially disposed about the hub. The spring, in one example, is a Belleville type washer. In one particular embodiment, the Belleville washer is compressed between the axle housing of the flywheel and the clutch plate. The clutch may also include a clutch plate collar operably associated with the sprocket, the clutch plate collar positioned between the clutch plate and the spring. 
     Also, the invention includes an exercise bicycle frame for use with the clutch mechanism. The frame includes a front support, a rear support, and a brace member extending between the front and rear ground supports. In addition, front forks are included that have a top end and a bottom end, and are attached at the bottom end to the front ground support. The front forks rotatably support a high-inertia flywheel. A rear post is included that has a top member and a bottom member, the top member attaching to the bottom member in a rear offset overlapping manner, the rear post defining a top end and a bottom end. The rear post is attached at the bottom end to the brace member. An articulated beam is attached to and extends from the top end of the front forks downwardly and rearwardly to a midpoint between the front forks and the rear post, then extends horizontally to the rear post at the intersection of the top and bottom members of the rear post. A rear truss extends from the top member of the rear post to the rear support. A handlebar is attached at the top end of the front forks, and a seat is attached at the top end of the rear post. A front area is defined by the front forks, articulated beam, rear post and brace member forming a five-sided polygon, and a rear area is defined by the rear post, rear truss, and brace member forming a five-sided polygon. 
     Accordingly, it is one object of the present invention to provide a free-wheeling clutch mechanism that allows an exercise bike to include the direct-drive relationship between the drive train and the flywheel, and at the same time allow the drive train and the flywheel to turn independently from one another under certain conditions. 
     Other aspects, features and details of the present invention can be more completely understood by reference to the following detailed description in conjunction with the drawings, and from the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exercise bicycle incorporating the clutch mechanism of the present invention. 
         FIG. 2  is a schematic representation of the drive train of the exercise bicycle shown in  FIG. 1 . 
         FIG. 3  is a schematic representation of the drive train of the exercise bicycle shown in  FIG. 1 . 
         FIG. 4  is a section taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5A  is a section taken along line  5 A- 5 A of  FIG. 2   
         FIG. 5B  is a representative section similar to  FIG. 5A  showing the effects of worn clutch material. 
         FIG. 5C  is a representative section similar to  FIG. 5A  showing a different type of compression member. 
         FIG. 6  is a perspective view of a high-inertia flywheel incorporating one embodiment of the clutch mechanism of the present invention. 
         FIG. 7  is an exploded view of the flywheel of  FIG. 6 . 
         FIGS. 8 and 9  are elevation and perspective views, respectively, of a portion of the clutch mechanism. 
         FIG. 10  is a side view of the sprocket collar member of the clutch mechanism of the present invention. 
         FIG. 11  is a top view of the sprocket collar shown in  FIG. 10 . 
         FIG. 12  is a section taken along line  12 - 12  of  FIG. 10 . 
         FIG. 13  is an enlarged front perspective view of the sprocket collar of  FIG. 10 . 
         FIG. 14  is a side view of the clutch plate collar member of the clutch mechanism of the present invention. 
         FIG. 15  is a section taken along line  15 - 15  of  FIG. 14 . 
         FIG. 16  is a front perspective view of the clutch plate collar member of the clutch mechanism of the present invention. 
         FIG. 17  is a perspective view of a high-inertia flywheel incorporating an alternative embodiment of the clutch mechanism of the present invention. 
         FIG. 18  is an enlarged perspective view of the embodiment of the present invention as shown in  FIG. 17 . 
         FIG. 19  is a section taken along line  19 - 19  of  FIG. 18 . 
         FIG. 20  is a representative section of the embodiment shown in  FIG. 19 , showing the effect of worn clutch material. 
         FIG. 21  is an enlarged perspective view of another embodiment of the present invention. 
         FIG. 22  is a section taken along line  22 - 22  of  FIG. 21 . 
         FIG. 23  is a section taken along line  23 - 23  of  FIG. 22 . 
         FIG. 24  is a representative section of an alternative embodiment similar to that shown in  FIGS. 22 ,  23  and  24 . 
         FIG. 25  is an elevation view of another embodiment of the present invention. 
         FIG. 26  is a section taken along line  26 - 26  of  FIG. 25 . 
         FIG. 27  is an elevation view of another embodiment of the present invention. 
         FIG. 28  is a section taken along line  28 - 28  of  FIG. 27 . 
         FIG. 29  is a section taken along line  29 - 29  of  FIG. 28 . 
         FIG. 30  is a representative section of another embodiment of the present invention. 
         FIG. 31  is a representative section of an alternative embodiment of the present invention. 
         FIG. 32  is a representative section of an additional alternative embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In light of the above items, a free wheel clutch mechanism  40  has been developed for use on direct-drive exercise bicycles  42  utilizing an inertia flywheel  44  ( FIGS. 1-4 ). While the present invention is described below associated with an exercise bicycle, it is contemplated that it could be used on normal bicycles or other exercise equipment, including magnetic resistive bicycles, air-resistance bicycles and other non-bicycle exercisers (such as upper body exercisers), each having rotary-driven mechanisms (wheels, etc.), in the proper circumstances. The free wheel clutch mechanism works in a direct-drive manner when the rider pedals the bicycle in the forward direction (counter-clockwise in  FIGS. 1 and 2 , clockwise in  FIG. 3 ), but has a release, or free wheel, characteristic when the rider applies a required force on the pedal (or to the drive train somewhere) opposite or against the forward pedaling direction. Upon application of the appropriate opposite force (“break free force threshold”), the drive train free-wheels to allow the pedals to turn in the opposite direction with respect to, or more slowly than, the rotation of the flywheel. The rider can then either simply drive the pedals at a relatively lower rpm than the normal gear ratio to the flywheel, stop the pedals, or can rotate the pedals backwards. 
     The opposite force required to be applied to the pedals to cause the free wheeling action can be adjusted based on the design of the free wheel clutch mechanism, and is typically between 0.00 and 100 pounds, preferably 55 pounds at the pedals, depending on the application. The break free force threshold is based on the static frictional engagement between the clutch material and the clutch plates which the clutch material is clamped between, as well as the mechanical advantage provided through the drive train. The clutch plates, as defined below, are on different members that in normal circumstances are to rotate together. The friction force between the clutch material and the clutch plates facilitates this relationship. At a certain point (the break free force threshold), the opposing clutch plates overcome the static frictional force and spin at different speeds (r.p.m.&#39;s) in the same direction, or in the opposite direction. The surface area of the clutch plates and the clutch plate material, the material property of the clutch plates and the clutch material, and the force at which the clutch plates clamp the clutch material are all factors that can be specifically designed to affect the break free force threshold. The break free force (as measured at the pedal) is affected also by the gear ratio and the length of the crankarms. 
     The free wheel clutch mechanism  40  is integral to the drive train of the exercise bicycle. The drive or gear train includes the drive sprocket  46 , the crank arms  48  and associated pedals  50  attached to the drive sprocket, the drive axle assembly  52 , the slave sprocket  54 , and the chain or belt  56  that interconnects the drive and slave sprockets, as shown in  FIG. 3 . Typically, the drive sprocket is rigidly mounted to one of the crank arms, and each crank arm is removably mounted to the drive axle assembly. The drive axle assembly is positioned in the hub on the frame to allow rotating movement, in either direction of the crank arms. 
     As shown in  FIG. 4 , the free wheel clutch mechanism  40  includes a sprocket collar  58  rotatably mounted on a slave axle assembly  60 . The slave sprocket  54  is attached to the flywheel  44  adjacent to the hub  62 . The slave axle assembly is mounted in the hub, and attaches to the frame to allow the flywheel to rotate with respect to the frame, under the force of the drive train through the movement of the slave axle assembly. The slave axle assembly is actually mounted in the hub, and includes an axle housing. Typically, the slave sprocket is mounted on the axle housing. 
     The free wheel clutch mechanism can be mounted in association with the drive sprocket, cranks and drive axle assembly, or can be mounted in association with the slave sprocket, slave axle assembly and flywheel. The placement of the free wheel clutch mechanism is a matter of choice dependent on the particular implementation. The only difference between the two positions of the free wheel clutch mechanism is that when mounted in association with the slave sprocket, the actuation of the free wheel clutch mechanism affects the movement of the chain and drive sprocket (slow down, stop or reverse). When the free wheel clutch mechanism is mounted in association with the drive sprocket, the actuation of the free wheel clutch mechanism allows the pedals and cranks to be slowed down, stopped, or reversed while the drive sprocket, chain and slave sprocket and flywheel continue to rotate. As described herein, the free wheel clutch mechanism is mounted in association with the slave sprocket. 
     More specifically as shown in  FIGS. 4 and 5A , the free wheel clutch mechanism includes a sprocket collar  58  (in this case a “slave” sprocket collar) that is mounted in a one-way drive relationship with the axle housing  64  such that the rotation of the slave sprocket collar in one direction directly drives the axle housing, and the rotation of the slave sprocket collar in the reverse direction does not drive the axle housing (allows “free-wheeling”). This free wheeling relationship is established by one-way bearings  66  or a ratchet and pawl structure used between the slave sprocket collar and the axle housing. 
     The free wheeling motion of the slave sprocket collar  58  with respect to the axle housing  64  (and hence hub  62  and flywheel  44 ) is tempered, or reduced, by clutch plates  68  and clutch or braking material  70  acting upon the slave sprocket collar. A clutch plate collar  69  is secured to the axle housing  64  to fixedly position one end of the free wheel clutch mechanism  40 . The clutch plates  68  are rigidly mounted to turn with the axle housing (and hence the hub and flywheel), and are forced into contact with the sprocket collar  58  by a biasing means, such as a spring member  72 . The braking material  70  is positioned between the sprocket collar and the clutch plates to provide a frictional interface between the two. The braking material can be mounted to either the sprocket collar, the clutch plates, or can be free-floating. The area of contact between the clutch plate and the sprocket collar (through the braking material) in combination with the compression force applied by the biasing means  72 , creates the “break free” force required to be applied through the sprocket collar to allow the sprocket collar to “free wheel” on the axle housing. If the applied force is not sufficient to overcome the “break free” force, then the sprocket collar is not able to free wheel on the axle housing. 
     The free wheeling clutch mechanism is self-adjusting under the bias force to accommodate for the reduction in thickness of the braking material  70  wearing out through use. The clutch plates  68  “float” on the axle housing to adjust and maintain contact with the sprocket collar as the braking material becomes thinner. 
     Particular embodiments of the free wheeling clutch mechanism are described in more detail below. 
     An exercise bicycle  42  incorporating the present invention is shown in  FIG. 1 . The bicycle includes a frame  80  supported on a support surface by ground engagement members  82 , an adjustable seat  84 , adjustable handlebars  86 , a flywheel  44  rotatably positioned between a pair of front forks  88  of the frame, and a gear train  54  attached to the frame adjacent to and below the seat. 
     The frame  80 , as shown in  FIG. 1 , includes front and rear ground supports  90  attached by a horizontal frame brace member  92  extending there between, front forks  88 , and a rear post  94 . The front forks and rear post are attached by an articulated beam  96  sloping from the top of the front forks down to approximately midway between the front forks and the rear post, at which point the articulated beam extends horizontally rearwardly to engage the rear post. The articulated beam thus includes two members connected at an angle to one another, and extends between the top of the forks to the approximate midpoint of the rear post. 
     An aperture is formed at the top of the forks to receive a handlebar post  98 , the handlebar post being vertically adjustable in the top of the forks by a pop-pin structure, as is known in the industry. Handlebars are attached to the top of the handlebar post in any known manner for use by the rider. An aperture is formed in the top of the rear post for receiving a seat post  100 . The seat post is vertically adjustable in the rear post by a pop-pin structure, as is well known in the art. The seat can be forwardly and rearwardly adjusted on the seat post, such as by the mechanism disclosed in U.S. Pat. No. 4,772,069 to Szymski, incorporated herein by reference, in addition to being vertically adjustable. 
     The rear post  94  includes a top member  102  and a bottom member  104 . The top member  102  is attached to extend from the rear side of the bottom member  104 , and extends beyond the top of the bottom member  104  in a rear-offset overlapping manner. The articulated beam  96  is affixed to the rear post  94  at the top of the bottom member  104  and the front side of the top member  102 . This attachment of the articulated beam to the rear post forms a strong structural connection. 
     The crank arms  48  for each of the pedals  50  are attached to a hub  106  which is supported by the rear post at a location along the height of the rear post where the bottom and top members of the rear post coextend. The rear post  94  attaches to the horizontal frame member  92  about midway between the front and rear ground support members  90 . A rear truss  107  extends at an angle from the rear post  94  down to the rear ground support member  90  for added strength. The frame is constructed of rectangular or hollow cylindrical steel tubing, as is known in the art. Rectangular tubing is preferred. 
     The front area defined by the forks  88 , articulated beam  96 , rear post  94 , and horizontal frame member  92  is a five-sided polygon. The rear area defined by the rear post  94 , rear truss  107  and horizontal frame member  92  is also a five-sided polygon. A friction break  108  is mounted adjacent to the top of the front forks to selectively engage the opposing outer rims of the flywheel  44  to provide an additional friction load against which the rider must work in exercising on the exercise bicycle. This frame design, to the geometry of the frame structure, is very strong and durable, and is capable of withstanding the rigors of frequent use. The portion of the frame that supports the crank arms and chain ring is especially strong and durable in this design as a result of the overlapped construction of the rear post  94 . 
     As shown in  FIGS. 1 ,  2  and  3 , the drive or gear train (as described above) includes a drive sprocket  46  rotatably mounted on the frame, crank arms  48  and associated pedals  50  attached to the drive sprocket for driving the drive sprocket, a free wheel clutch assembly  40 , a slave sprocket  54  attached on the flywheel  44 , and a chain  56  connecting the drive sprocket to the slave sprocket, and to the free wheel clutch assembly. The chain could be replaced by a belt with accommodating modifications made to the drive and slave sprockets, with no adverse affect on the operation of the free-wheeling clutch mechanism of the present invention. 
     As with a standard direct drive exercise bicycle, the rider pedals the exercise bicycle using the crank arms and pedals, to drive the drive sprocket  46 . The chain  56 , engaged between the drive sprocket and slave sprocket  54 , causes the flywheel  44  to rotate at the given rpms based on the gear ratio between the drive sprocket and the slave sprocket. 
     The free wheel clutch mechanism  40  engages the flywheel, as is described below, to allow the transfer of rotational movement from the slave sprocket  54  to the flywheel  44  in a direct-drive relationship when driven in the forward direction. Normal pedaling circumstances include the use of the exercise bicycle during an organized exercise class or individually, and include starting at 0.00 rpms and increasing and decreasing the rpms as is required or desired for certain exercise programs, whether the rider is standing, sitting or alternating during use. The free wheel clutch mechanism  40  of the present invention maintains the “pedal-through” benefit of standard direct drive exercise bicycles. The pedal-through benefit helps the rider pedal continuously and smoothly through the top and bottom pedal positions where riders typically are weakest. 
     The free wheel clutch mechanism  40  converts the direct drive relationship between the pedal revolutions and the flywheel revolutions to a “free wheel” relationship to allow the pedals  50  to be stopped, reversed in direction, or rotated more slowly than the flywheel  44 , when a sufficient force is applied in the reverse direction to either of the pedals or anywhere on the drive train (where the clutch mechanism is positioned on the inertia wheel). Examples of the application of an opposite force include, but are not limited to, the intentional application of the reverse force by the rider while pedaling, for instance due to fatigue, or the contact of the pedal on the rider&#39;s lower leg when a foot is accidentally released from the pedal. 
     As shown in  FIGS. 4 ,  5 A,  5 B,  6  and  7 , the free wheel clutch mechanism  40  mounts on the slave axle assembly  60  adjacent to the hub  62  of the flywheel  44 . A cylindrical slave axle housing  64  is press-fit into a cylindrical axial bore formed through the hub  62  of the flywheel. The end of the axle housing extending from the hub is externally threaded to receive the clutch plate collar  69 . 
     In the description below, the terms “inside” and “inner” refer to the end closest to the flywheel  44 , and the terms “outside” and “outer” refer to the end farthest from the flywheel. The clutch plate collar  69  includes a hollow cylindrical main body  118  with internal threads at one end for engagement with the external threads on the outer end of the axle housing  64 . The clutch plate collar  69  has an outer radially extending engagement flange  120  attached to the outside end of the cylindrical main body  118 , and an inner radially extending engagement flange  122  movably attached to the inside end of the cylindrical main body. 
     Referring to  FIGS. 5A and 5B , the inner flange  122  is able to move axially (longitudinally) along the all or a portion of the length of the cylindrical main body  118  of the clutch plate collar  69 . Referring to  FIGS. 7 ,  8  and  9 , the inner flange  122  has a central bore  124 , defining a plurality of radially inwardly extending keys  126 . Corresponding longitudinally extending slots  128  are formed on the surface of the cylindrical main body of the clutch plate collar  69  at its inner end, and extend at least partially along the length of the main body, to receive the keys  126  and allow the inner flange  122  to move (float) axially along the length of the cylindrical main body, to the extent of the length of the slots. The benefit of the axial movement of the inner flange of the clutch plate collar  69  is described in more detail below. When the cylindrical main body  118  is threadedly connected to the axle housing  64 , the inner flange is positioned so the keys are slidably received in the slots, and the inner flange is retained on the end of the cylindrical main body by the hub  62  or the axle housing (by end of axle housing as shown in  FIG. 5A ). The intersection of the keys  126  in the slots  128  make the inner flange turn with the cylindrical main body  118 . 
     A one-way bearing  66 , such as an INA shell-type roller clutch as found in the INA Bearing Company, Inc. of Fort Mill, S.C., catalog #305, 1988 at page 164, is mounted on the cylindrical main body  118  of the clutch plate collar  69  between the end of the slots  128  and the outer flange  120 . The rollers of the bearing  66  engage the outer surface of the cylindrical main body member  118 , and can slide (float) along the length of the main body, as described in more detail below. The one-way bearing permits direct-drive in one direction, and free-wheeling in the other rotational direction, also described in more detail below. 
     Referring to  FIGS. 5A ,  7 , and  10 - 13 , a sprocket collar  58  defines a central bore and is positioned concentrically over the cylindrical main body member  118  of the clutch plate collar  69 , and is attached to the outer race of the one-way bearing. The sprocket collar  58  defines an outer radially extending engagement collar  130  spaced away but substantially coextensive with the outer flange  120  of the clutch plate collar  69 , an inner radially extending engagement collar  132  spaced away from but substantially coextensive with the inner flange  122  of the clutch plate collar  69 , and the slave sprocket  54  formed about the outer surface of the sprocket collar  58  and between the inner and outer extending collars  130  and  132 . The chain  56  engages the slave sprocket  54 . The engagement collars  130  and  132  are extensions of the sidewalls of the sprocket collar, and provide more surface area if needed for the clutch-function they perform, as defined below. 
     The following explains the relative movement and drive characteristics of the clutch plate collar  69 , sprocket collar  58 , and flywheel  44  with the structure described at this point. When the slave sprocket  54  is driven in the forward direction (clockwise with respect to  FIG. 3 , counter-clockwise with respect to  FIGS. 1 and 2 ) by the chain  56 , the one-way bearing  66  engages and causes the slave sprocket  54  to rotate the sprocket collar  58 , in turn rotating the clutch plate collar  69 , which in turn rotates the axle housing  64 , which causes the flywheel to turn. If the slave sprocket  54  is caused to move in the opposite direction (counter-clockwise in  FIG. 3 , clockwise in  FIGS. 1 and 2 ), the one-way bearing would allow the sprocket collar  58  to free-wheel on the clutch plate collar  69 . 
     Ideally a friction clutch or braking material  70  in the form of a flat washer (a disk with a central aperture formed therein) is positioned between the outer flange  120  of the clutch plate collar  69  and the outer collar  130  of the sprocket collar  58 , and between the inner flange  122  of the clutch plate collar  69  and the inner collar  132  of the sprocket collar, as best shown in  FIGS. 5A ,  5 B, and  7 . The friction clutch material  70  can be attached to either the outer flange  120  or the outer collar  130 , and the friction clutch material  70  can be attached to either the inner flange  122  or the inner collar  132 , to anchor the clutch material. The clutch material  70  can be felt, cork, standard brake material, or any material that provides a sufficient frictional relationship between the coextensive flanges and collars. Preferably, clutch facing, as shown in McMaster-Carr Company catalog number 101, 1995, at page 2530, is used at a thickness of approximately 2.0 mm. Insert description for collar for inside diameter for free-floating and not connected to either side. In some instances, such as when the clutch material is not attached to either the clutch plate collar or the sprocket collar, but instead just floats between the two, a bearing washer is attached to the perimeter of the central aperture to help support the clutch material on the axle housing. 
     Compression means, such as a compression spring  72 , is positioned around the hub  62  of the flywheel  44  to engage the inner flange  122  of the clutch plate collar  69  to bias the inner flange toward the outer flange  120  of the clutch plate collar. The spring  72 , such as a jumbo compression spring in the McMaster-Carr catalog number  101 , biases the inner flange  122  outwardly to clamp the clutch material  70  between it and the inner collar  132 , and also clamps the clutch material  70  between the outer collar  130  and the outer flange  120 . The designed axial movement of the inner race (such as by sliding) on the cylindrical main bearing  66  (keys  126  sliding in the slots  128 ) allows the sprocket collar  58  to float and transmit the force of the spring  72  to the outer flange  120 . The combination of the bias force created by the spring  72 , and the engagement of the clutch plate collar  69  and the sprocket collar  58  with the clutch material  70  in between creates a friction force having an upper limit (“break free”) force required to cause the sprocket collar  58  to move independently of the clutch plate collar in the reverse direction. 
     For instance, where the spring force is approximately 225 pounds when fully compressed, and the clutch material has an inner diameter of 1.65 inches and an outer diameter of 2.52 inches, where two clutch material disks were used ( FIG. 5B ), the break free force has been tested to be approximately 55 pounds at the pedal. It has been found that as the spring extends due to wear of the clutch material, the spring force reduces to approximately 200 pounds, and the break free force actually increases. This is believed to be due to the fact that the engaging surfaces clamping the clutch material become polished and increase the surface area, thus increasing the static friction force to be overcome. 
     The following explains the relative movement of the clutch plate collar  69 , sprocket collar  58  and flywheel  44  given the structure described to this point. When the slave sprocket  54  is driven in the forward direction, as defined above, the one-way bearing creates the direct-drive relationship with the flywheel  44  desired for this type of exercise bicycle. When the slave sprocket  54  is driven in the backward direction, or there is a reverse force applied to the slave sprocket to attempt to rotate it in a direction opposite the direction of rotation of the flywheel, the one-way bearing does not drive the flywheel  44 , but instead allows the pedals to free wheel. However, the friction force generated between the clutch plate collar  69  and the sprocket collar  58  due to the engagement of the outer flange  120  and the outer collar  130  with the inter-positioned clutch material  70 , and the inner flange  122  and inner collar  132  with the inter-positioned clutch material  70 , acts to create a threshold friction force that must be overcome to allow the rider to drive the sprocket collar  58  independent of the flywheel  44 . If the force applied by the rider to the pedals is large enough to overcome the friction (“break free”) force, then the pedals cause the sprocket collar  58  to turn independently of the clutch plate collar  69 , with the clutch material  70  being rubbed and worn down in the process. 
     As the clutch material  70  wears down and becomes thinner, the spring  72  extends to push the inner flange  122  (floating) along the slots to maintain the appropriate force on the clutch material  70 . The sprocket collar  58  is also pushed outwardly to maintain the desired force, and resulting “break free” characteristics. The spring  72  thus allows for automatic adjustment to compensate for the wear of the clutch material  70 . The spring  72  must be selected to have a relatively predictable and stable spring constant along its length of extension to insure the development of the proper friction forces. The spring can be replaced with an elastomeric tube  73  having sufficient spring properties in the axial direction, such as is shown in  FIG. 5C . Some elastomeric materials have very stable spring constants. One such suitable elastomeric material is a polyurethane made by Kryptonics Inc. of Louisville, Colo. Preferably, the tube  73  is approximately 1 inch long, 0.887 inches when initially compressed, and has a wall thickness of approximately 0.225 inches. In addition, an adjustable compression spring could also be used that would allow the spring force to be adjusted to modify the break free force when desired. 
     The inner or outer clutch material  70  can be replaced by a bearing if it is desired to use only one clutch material  70 . The break-free force threshold may be modified accordingly as a result. 
     Similar relative movement is found when the exercise bicycle incorporating the present invention is in use, and more clearly depicts the advantages of the free wheel clutch mechanism of the present invention. When a rider is exercising on the exercise bicycle, the forward drive of the drive train causes the slave sprocket  54  to drive the sprocket collar  58  in the direction of engagement of the one-way bearing, in the end to drive the flywheel  44  in a direct drive manner. If the rider desires, by applying a force of approximately 50 pounds in the opposite direction, the threshold friction force between the clutch plate collar  69 , the sprocket collar  58  and the clutch material  70  is overcome (the “break free” force), and the sprocket collar  58  can free wheel with respect to the clutch plate collar  69  and the flywheel  44 . The sprocket collar  58  thus moves in the opposite direction with respect to the direction of rotation of the flywheel  44 . The rider can thus pedal irrespective of the movement of the flywheel  44  until the friction between the clutch plate collar and the sprocket collar (caused by the clutch material) reduces the rpms of the flywheel to a point where, based on the gear ratio, the rpms match to cause “lock-up”. 
     In a more extreme situation, if the foot of the rider slips off the pedal and the pedal strikes the rider&#39;s leg, a sufficient force is generated to overcome the “break free” force and the pedals can stop to reduce the chance of serious injury, letting the flywheel continue to rotate until the friction force stops the rotation of the flywheel. 
     An axle  134  ( FIGS. 5A and 5B ) is positioned through the bore in the hub, with associated bearings to support the flywheel  44  and allow it to rotate as driven by the gear train. 
     The one-way bearing is not necessary for the application to work on an exercise bicycle. However, without the one-way bearing the sprocket collar would “free wheel” in the forward direction too when the drive force was greater than the “break free” force, thus limiting the amount of force the rider could apply while pedaling the bicycle in the forward direction. 
     The one-way bearing  66  can be replaced by a spring-loaded ratchet and pawl drive mechanism found in normal bicycle applications, or other one way drive mechanisms that can functionally replace the one-way bearing described above. One such suitable commonly available ratchet and pawl mechanism is the LMA-8 from the LIDA Machinery Company, Ltd. of Taoyuan, Taiwan, as shown in the Taiwan Bicycle Source 1997-98 catalog at p. 370. 
       FIGS. 8 through 16  show details of some of the components described above. 
     An alternative embodiment of the free wheel clutch mechanism is shown in  FIGS. 17-20 . This alternative embodiment works on the same principle as the first embodiment described above, except basically replaces the single large spring surrounding the hub  150  with the plurality of smaller springs  152  positioned between the flywheel  154  and the inner clutch plate  156 . These plurality of springs  152  act to push the inner clutch plate  156  outwardly as the clutch material  158  wears down from use. As can best be seen in  FIGS. 19 and 20 , each of the plurality of springs surrounds a guide rod  160  mounted to the flywheel  154  which is received in a guide bore  162  mounted to and extending from the inside side of the inner clutch plate  156 . The sliding interaction between the guide rod  160  and the guide bore  162  helps ensure that the inner clutch plate  156  is squarely moved outwardly under the bias of the springs as the clutch material wears as a result of use. The interaction of the guide rod with the guide bore also causes the inner clutch plate  156  to turn with the flywheel  154  because the guide rods are laterally fixed in position inside the guide bores, and as the guide rods turn with the movement of the flywheel, they cause the inner clutch plate to turn also. 
     The axle housing  164  is press-fit into the hub  150  and extends from the flywheel  154 , and has an outer end  166  with external threads. After the inner clutch plate  156  and associated compression springs  152  are mounted over the axle housing and positioned adjacent the hub, the slave gear collar  170  is positioned to engage the outer surface of the axle housing  164  as in the previous embodiment, including having the same bearing structure  172 . The slave gear collar has an inner surface  174  adjacent the outer surface  176  of the inner clutch plate, between which is positioned an inner clutch material washer  178 . The inner clutch material washer  178  is preferably fixed to either the outer surface of the inner clutch plate  156  or the inner surface of the slave gear collar  170 . A set of gear teeth  180  are formed about the outer circumference of the slave gear collar  170  for receiving the chain used to drive the flywheel. 
     The outer clutch plate  182  (or anchor plate) is then threaded on to the externally threaded outer end  184  of the axle housing. An outer clutch material washer  186  is positioned between the outer surface of the slave gear collar  170  and the inner surface of the outer clutch plate  182 . Preferably, the outer clutch material washer  186  is fixed to either the outer surface of the slave gear collar  170  or the inner surface of the outer clutch plate  182 . The outer clutch plate is fixed to the axle housing by a lock-nut  188  to keep the outer clutch plate from turning loose under the force of the free wheel mechanism. 
     This alternative embodiment of the present invention operates in fundamentally the same manner as the previously described embodiment. When a reverse force is applied to the drive train, normally through a reverse force being applied to the pedals, and this reverse force overcomes the “break free” force, the slave gear overcomes the friction force between the slave gear collar  170  and the outer clutch plate  182  and inner clutch plate  156  which rotate with the flywheel  154 . This allows the flywheel to continue spinning while the drive train is either stopped, pedaled backwards, or pedaled more slowly than the flywheel is spinning. The bearings  172  connecting the slave gear collar  170  to the axle housing  164  are one-way bearings as described above, and when the drive train is actuated in the normal or forward direction, the bearings lock and act as a direct drive connection between the drive train and the flywheel. 
     When turned in the reverse direction, the bearings  172  allow the slave gear collar  170  to free-wheel, the free wheeling of which is restricted by the frictional engagement of the slave gear collar  170  with the surrounding clutch material  178 ,  186 . The compression springs  152  apply the force to the inner clutch plate  156  which presses the inner clutch material  178  against the slave gear collar. The slave gear collar  170  can move longitudinally on the axle housing  164  (the bearing allows small amounts of movement in this direction) and thus transmits a force to the outer clutch material  186 , and finally to the outer clutch plate  182 . As the inner or outer clutch material wears down, the springs  152  extend and push the inner clutch plate  156  outwardly and thus maintain the contact necessary for the frictional engagement between the inner clutch plate  156 , the inner clutch material  178 , the slave gear collar  170 , the outer clutch material  186 , and the outer clutch/anchor plate  182 . 
       FIG. 20  shows the adjusted relationship of the structure of this alternative embodiment when the inner and outer clutch material washers  178 ,  186  have worn down. Contrasting  FIGS. 19 and 20 , note the gap between the inner clutch plate  156  and the outer end of the hub  150 . The bearings  172  allow the slave gear collar  170  to move longitudinally on the axle housing  164 . Either one of the inner or outer clutch materials  178 ,  186  can be replaced with a bearing if it is determined that they are unnecessary. 
     Another alternative embodiment is shown in  FIGS. 21-23 . In this alternative embodiment a Belleville washer  200  is mounted on the end of the axle housing  202  to bias the outer clutch plate  204  inwardly to create the desired friction force between the slave gear collar  206  and the outer and inner clutch plates  204 ,  208  through the inner and outer clutch material washers  210 ,  212 . In the second alternative embodiment a retainer  214  having an outwardly flanged inner end  215  is threaded on to the end of the axle housing  202  extending from the hub  216 , which has external threads. The outwardly extending flange  215  of the retainer butts up against the hub  216 . The inner clutch plate  208  is then positioned next to the outwardly extending flange  215  and is retained in rotational position therewith by keys in slots or by any other suitable attachment method, such as welding (as shown in  FIG. 22 ). Alternatively, the outwardly extending flange can act as the inner clutch plate. 
     An inner clutch material washer  210  is positioned adjacent to and in contact with the inner clutch plate  208 , and the slave gear collar  206  is mounted over the cylindrical body of the retainer  214 . The slave gear collar  206  is similar to the slave gear collars described in the previous two embodiments and includes a bearing  218  positioned between the slave gear collar  206  and the outer circumference of the retainer  214 , the bearing  218  being a one-way bearing allowing the slave gear collar  206  to free-wheel when turned in a reverse direction, and locking to provide a direct drive when turned in the forward direction. Gear teeth  220  are formed on the outer circumference of the slave gear collar  206  for engagement with the chain of the drive train. An outer clutch plate  204  is positioned over the outer circumference of the retainer  214 . As shown in  FIG. 23 , the outer clutch plate  204  defines a central bore  222  having at least one key  224  formed for mating insertion into a corresponding slot formed in the retainer  214 . The mating key and slot relationship between the outer clutch plate  204  and the retainer  214  makes the outer clutch plate turn with the flywheel because the retainer turns with the flywheel  226  and the rotational interference between the key and the slot causes the outer clutch plate  204  to turn also, in addition to allowing the outer clutch plate to float or move inwardly and outwardly with respect to the inner clutch plate  208  along the body of the retainer as the friction clutch material  210 ,  212  wears down. 
     The Belleville washer  200  is positioned about the end of the axle housing to engage the outer clutch plate  204  with the bias force. The bias force is created by an outer retainer  228  which defines a cylindrical main body  230  having external threads and an outwardly extending flange  232  at one end. The outer end of the axle housing  202  defines internal threading  234  such that the cylindrical main body  230  of the outer retainer  228  threads into the outer end of the axle housing  202  to the point where the outwardly extending flange  232  abuts the outer end of the axle housing and also engages the inner rim of the Belleville washer  200  to compress the Belleville washer against the outer clutch plate  204 . The compression of the Belleville washer  200  against the outer clutch plate  204  causes the outer clutch plate to be biased inwardly against the outer friction clutch material  212 , which is pushed against the slave gear collar  206 , which in turn is allowed to relatively float on the outer surface of the inner retainer  214  to push against the inner clutch material  210  and in turn frictionally engage the inner clutch plate  208 . 
     As the slave gear collar  206  is driven in the forward direction by the drive train, the one-way bearings  218  lock and create a direct drive relationship. When a sufficient reverse force is applied to the slave gear collar through the drive train, the one-way bearings release and allow the drive train collar to free-wheel under the influence of the frictional relationship with the inner and outer clutch plates, similar to the interaction as described with respect to the embodiments above. 
     As the clutch material  210 ,  212  wears down and becomes thinner, the Belleville washer  200  extends to continue to create a friction force in the clutch system by pushing the outer clutch plate  204  towards the inner clutch plate  208 , thereby clamping the inner and outer clutch material and the slave gear collar  206  therebetween. 
     Another alternative embodiment is disclosed in  FIG. 24  which shows two Belleville washers  240 ,  242  positioned back to back to allow for a longer adjustment stroke due to the wear of the inner and outer clutch material washers  244 ,  246 . In this third embodiment the outwardly extending flange  248  of the second retainer  250  is enlarged to engage the outer rim of the second Belleville washer  240 . Belleville washers are very stiff and provide a great deal of force through the length of their extension. 
     Another alternative embodiment is disclosed in  FIGS. 25-26 . This fourth alternative embodiment utilizes a band-brake to create the frictional break-free force. The band-brake  260  includes a retainer  262  fixed to the flywheel  264  through which is positioned a spring loaded adjustment screw  266  which attaches to a housing  268 . The housing includes two guide slots  270  for slidably receiving tabs  272  formed on the flywheel. The housing is also fixed to the opposite ends of a belt  274 . The slidable engagement of the guide slots  270  on the tabs  272  help ensure a properly oriented adjustment of the band-brake by the spring loaded screw. The slots are formed in the housing of the band-brake, the housing being attached to a belt, with the band-brake material  276  attached to the inside surface a reinforcement sheathing  278  of the belt (as best seen in  FIG. 26 ). The tabs, spring loaded threaded screw, housing and belt are all fixed to rotate with the flywheel. The spring surrounding screw  266  makes the system self-adjusting for wear of the band material by applying a preferably constant tension load on the belt through the housing. The selection of the spring constant properties of the spring determines the amount of tension on the belt, and the amount of adjustment (displacement) the band-brake can accommodate. 
     As best shown in  FIG. 26 , the slave gear collar  280  defines an annular axial extension  282  which fits over a portion of the hub  284  without contacting the hub. This annular extension  282  defines an inner rim  286  and an outer rim  288 , between which is an engagement surface  290 . The band contacts the engagement surface  290  between the inner rim and the outer rim. The slave gear collar  280  includes the same bearing system as previously described for one-way engagement with the outer surface of the axle housing  292 . The proper positioning of the slave gear collar  280  is maintained on the axle housing by a large washer  294  which is tightly pressed against the outer surface of the slave gear collar by a nut  296  to keep the slave gear collar from becoming imbalanced. A second set of one-way bearings could be positioned between the annular extension  282  from the slave gear collar and the outer surface of the hub over which the slave gear collar annular extension is positioned. 
     As the drive train is actuated in the forward direction by the rider, the one-way bearing  298  between the slave gear collar  280  and the axle housing  292  engages to cause a direct drive relationship between the drive train and the flywheel, as in the previously described embodiments. In the event a sufficient reverse force is applied to the slave gear collar through the drive train, the one-way bearing  298  releases and allows the slave gear collar to free-wheel subject to the frictional engagement of the slave gear collar and the belt  274 . The engagement surface  290  is in frictional engagement with the belt to create the “break free” force. The “break free” force is determined by the tightness of the belt around the engagement surface on the annular extension  282  of the slave gear collar. This “break free” force resists the free wheeling of the slave gear collar on the axle housing  292  and provides the beneficial pedal-through feature of traditional direct drive exercise bicycles. It also allows the drive train to free-wheel when a sufficient reverse force is applied to the drive train, likely through the pedals and cranks, to allow the drive train to be driven at a relatively lower RPM than the flywheel, depending on the gear ratio. 
     As the frictional brake material  276  wears down, the housing  268  is adjusted by tightening the screw  266  to move the housing, and thus tighten the belt  274  around the annular extension  282  of the slave gear collar  280  to maintain the desired frictional engagement, resulting in the desired “break free” force. 
     Another alternative embodiment is shown in  FIGS. 27-29 . In this embodiment, the slave gear collar  300  has the same structure as the previous embodiment described, and is held in engagement with the axle housing  302  in the same manner. A compression brake housing  304  is mounted in engagement with the flywheel  306  and includes means  308  for causing engagement of arcuate compression members  310  with the engagement surface  312  on the slave gear (sprocket) collar annular extension  314 , between the inner and outer rims  316 ,  318 . The arcuate compression members  310  have a hard backing  320  and a frictional clutch material  32  (2 mated to their inner concave surface for engagement with the slave gear collar annular extension  314 . The brake housing  304  includes means  308  for radially adjusting the compression of the compression members against the annular extension  314 , such as set screws which are threadedly adjustable through the brake housing to engage the hard back surface  320  of the arcuate compression members  310  to press the frictional material  322  of the compression members against the engagement surface  312  of the annular extension. These means can be self-adjusting to accommodate wear of the friction material, such as by being spring-loaded set-screws. As the frictional clutch material wears down, the set screws  324  can be used to maintain the proper compression of the compression members  310  against the engagement surface  312 , which creates the desired “break free” force. 
     This embodiment operates in the same manner to allow a break free clutch mechanism on the flywheel as the previously described embodiments. The brake housing  304  is held in rotational fixed orientation with the flywheel by a pin  326  positioned through a slot  328  in the brake housing. The movement of the pin in the slot allows for uneven wear of the compression members  310 . 
     Another alternative embodiment is shown in  FIG. 30 . Only one side, the inner side  329  as shown, of the sprocket collar  330  is used to create a frictional engagement with an engagement flange  332  attached to the axle housing  334  at the hub  336  of the flywheel  338 . The sprocket collar is positioned on a sheath  333  threadably engaging the axle housing  334  at the hub  336 , with a one-way bearing  337  (or ratchet and pawl mechanism) positioned between the sprocket collar and the sheath  333  for the same purpose as disclosed above with many of the other embodiments. Clutch material  340  is positioned between the side  329  of the sprocket collar  330  and the engagement flange  332 , and can be attached to either one, to create the frictional engagement therebetween. The engagement flange is movable along the axle housing of the hub to allow the friction force to be kept at a relatively constant level as the clutch material wears out. This self-adjustment, as described above, occurs when the spring  342 , or other means, presses the engagement flange outwardly from the hub to clamp the clutch material against the inner side  329  of the sprocket collar  330 . The sprocket collar  330  is supported on the inner and outer sides by an inner  344  and outer  346  bearing, respectively. The inside edge  335  of the sheath forms the outer race for the inner bearing  344 , while the sprocket collar forms the inner race for both the inner  344  and outer  346  bearings. The outer race  348 , or cone, threadedly engages the outer end of the sheath  333  to hold the sprocket collar  330  in place and provide a thrust bearing against which the spring  342  pushes. 
       FIG. 31  illustrates an additional alternative embodiment of a free wheel clutch mechanism  360 . This embodiment operates in fundamentally the same way as previously described embodiments. When a reverse force is applied to the drive train, normally through a reverse force being applied to the pedals, and this reverse force overcomes the break-free force, the slave gear overcomes the friction force between the slave gear collar and the inner and outer clutch plates which rotate with the flywheel. 
     In this alternative embodiment, preferably a Belleville washer  362  is circumferentially mounted on an axle housing  364  between an inner clutch plate collar  366  and a spring tensioner  368  to bias the inner clutch plate  366  outwardly to create the desired friction force between the slave gear collar  370  and the inner and outer clutch plates ( 366 ,  372 ) through the inner and outer clutch plate material washers ( 374 ,  376 ). Alternatively, a biasing member such as a coil spring may be used in place of the Belleville washer  362 . 
     The spring tensioner  368  is coupled to the axle housing  364 , and positioned between the flywheel  378  and the inner clutch plate collar  366 . In this embodiment, the outside circumference  379  of the axle housing  364  extending between the outside edge  380  of the flywheel  378  and the inner clutch plate  366  is threaded. The spring tensioner  368  defines an internally threaded cylinder that threadedly engages the outside circumference  379  of the axle housing  364 . Preferably, the spring tensioner  368  defines an outwardly extending flange  381  circumferential to the axle housing  364  that is adapted to center the Belleville washer  362  about the axle housing  364 . 
     To provide space for the spring tensioner  368 , a portion of the flywheel hub  364  adjacent the free wheel clutch mechanism  360  is preferably removed. As shown in  FIG. 22 , preferably the portion of the hub  216  that extends outwardly from the main body of the flywheel  226  along the axle housing  202  to the inner retainer  214  ( 366 ) is removed. Alternatively, a longer axle housing than illustrated in  FIG. 22  may be used. Alternatively, the portion of the flywheel hub is not removed, and the Belleview washer  362  is positioned between the outside edge  215  of the flywheel hub  216  and the inner clutch plate collar  366 , and a spring tensioner is not included. 
     In the preferred configuration, the Belleville spring  362  is positioned between the inner clutch plate collar  366  and the spring tensioner  368  to create the bias force. The bias force is created by compression of the Belleville spring  362  between the spring tensioner  368  and the inner clutch plate collar  366 . One advantage of this embodiment is that the spring tensioner  368  may be rotated about the threaded outside circumference  379  of the axle housing  364  to move the spring tensioner  368  outwardly or inwardly, and accordingly easily adjust the break-free force of the flywheel. Rotating the spring tensioner about the threaded axle housing  379  so as to move the spring tensioner  368  outwardly will increase the compression of the Belleville washer, and hence increase the break-free force. Rotating the spring tensioner  368  about the threaded axle housing  379  so as to move the spring tensioner inwardly will decrease the compression of the Belleville washer  362 , and hence decrease the break-free force. The compression of the Belleville washer  362  against the inner clutch plate collar  366  causes the inner clutch plate to be biased inwardly against the inner friction material  376 , which is pushed against the slave gear collar  370 , which in turn is pushed against the outer clutch plate material  374  and in turn frictionally engages the outer clutch plate collar  372 . 
     An additional advantage of this embodiment is that frictional engagement of the free wheel clutch mechanism  360  may be applied with preferably about 1.5 turns of the spring tensioner  368  about the axle housing. This provides for simple removal and unloading of the device. Additionally, as the clutch material ( 374 ,  376 ) wears down and becomes thinner, the compression of the Belleville washer  362  may be readily adjusted by way of rotation of the spring tensioner  368 . As with other embodiments described herein, as the clutch plate material ( 374 ,  376 ) wears down, the Belleville washer  362  will extend and maintain the friction force on the clutch system  360 . The break-free force, however, will decrease unless appropriate adjustments are made with the spring tensioner  368 . 
     The inner clutch plate washer  376  is positioned adjacent to and in contact with the inner clutch plate  366 , and the slave gear collar  370  is similar to the slave gear collars described in previous embodiments and includes a bearing  382  positioned between the slave gear collar  370  and the outer circumference of the outer clutch plate body  372 , the bearing  382  being a two-way bearing allowing the slave gear collar  370  to free-wheel when turned in a reverse direction, and locking to provide a direct drive when turned in the forward direction. Preferably, an INA Bearing Company shell-type roller clutch bearing as described previously herein is used. Gear teeth are formed on the outer circumference of the slave gear collar  370  (or sprocket) for engagement with the chain of the drive train. As the slave gear collar  370  is driven in the forward direction by the drive train, the one-way bearings lock and create a direct drive relationship. When sufficient reverse drive force is applied to the slave gear collar  370  through the drive train and the break-free force is exceeded, the one-way bearings release and allow the drive train collar to free-wheel under the influence of the frictional relationship with the inner and outer clutch plates, similar to the interaction described with respect to the other embodiments herein. 
     In this embodiment, the clutch plate material ( 374 ,  376 ) is preferably a hard plastic such as Polyethylene, which has advantageous wear characteristics. Using the hard plastic as the clutch plate material, preferably 900 lb. of friction force is applied to the freewheel clutch  360  through the Belleville washer  362  using the spring tensioner  368 . To adjust the friction, or break free force, the spring tensioner preferably includes a radial hole in its outside circumference in which a dowel may be inserted to rotate the spring tensioner. The friction force on the Belleville washer may range from between 0 lb. to about 1200 lb. depending on how the spring tensioner is adjusted. At the pedals, the break-free torque is preferably about 344 in.-lb. to about 444 in.-lb. The preferred specifications of the Belleville washer are: OD=55.8 mm; ID=28.6 mm; Thickness (uncompressed)=2 mm; 830 (+/−20) lb. at 75% compression; 1110 (+/−30) lb. at 100% compression; Material=SAE 1075. 
     Similar to the embodiment illustrated in  FIG. 5   a,  the outer clutch plate collar  372  includes a hollow cylindrical main body  384  with internal threads at one end for engagement with the external threads on the outer end  386  of the axle housing  364 . The clutch plate collar  372  defines an outer radially extending engagement flange  388  attached to the outside end of the main body, and an inner radially extending flange, which is the inner clutch plate  366 , movably attached to the inside end of the cylindrical main body  384 . The inner clutch plate  366  is able to move axially (longitudinally) along all or a portion of the length of the cylinder main body  384  of the outer clutch plate collar  372 . As shown with reference to the embodiments illustrated in  FIGS. 7 ,  8 , and  9 , the inner flange  366  has a central bore  124  defining a plurality of radially inwardly extending keys  126 . Corresponding longitudinally extending slots  128  are formed on the surface of the cylindrical main body of the outer clutch plate collar  372  at its inner end, and extend at least partially along the length of the main body, to receive keys  126  and allow the inner flange to move (float) axially along the length of the cylindrical main body  384 , to the extent of the length of the slots. When the cylindrical main body  384  is threadedly connected to the axle housing  364 , the inner flange  366  is positioned so the keys  126  are slidably received in the slots, and the inner flange  366  is retained on the end of the cylindrical main body  384  by the axle housing  364 . The intersection of the keys in the slots make the inner flange turn with the cylindrical main body. 
       FIG. 32  illustrates an additional alternative embodiment of a free wheel clutch mechanism  390 . This embodiment operates in fundamentally the same way as previously described embodiments. When a reverse force is applied to the drive train, normally through a reverse force being applied to the pedals, and this reverse force overcomes the break-free force, the slave gear overcomes the friction force between the slave gear collar and the inner and outer clutch plates which rotate with a flywheel  391 . 
     In this alternative embodiment, a Belleville washer  392  is circumferentially mounted on an axle housing  394  between an inner clutch plate collar  396  and a circumferential wall  398  of the axle housing to bias the inner clutch plate  396  outwardly to create the desired friction force between a slave gear collar  400  and the inner and an outer clutch plate ( 396 ,  402 ) through an inner and an outer clutch plate material washer ( 404 ,  406 ). Alternatively, a biasing member such as a coil spring may be used in place of the Belleville washer  392 . 
     The inner clutch plate washer  404  is positioned adjacent to and in contact with the inner clutch plate  396 . The slave gear collar  400  is similar to the slave gear collars described in previous embodiments and includes a bearing  408  positioned between the slave gear collar  400  and the outer circumference of the outer clutch plate body  402 . The bearing  408  is a two-way bearing allowing the slave gear collar  400  to free-wheel when turned in a reverse direction, and locking to provide a direct drive when turned in the forward direction. In one example, an INA Bearing Company shell-type roller clutch bearing issued as described previously herein. Gear teeth are formed on the outer circumference of the slave gear collar  400  (or sprocket) for engagement with the chain of the drive train. As the slave gear collar  400  is driven in the forward direction by the drive train, the one-way bearings lock and create a direct drive relationship. When sufficient reverse drive force is applied to the slave gear collar  400  through the drive train and the break-free force is exceeded, the one-way bearings release and allow the drive train collar to free-wheel under the influence of the frictional relationship with the inner and outer clutch plates, similar to the interaction described with respect to the other embodiments herein. 
     In one example, the clutch plate material ( 404 ,  406 ) is a hard plastic such as Polyethylene, which has advantageous wear characteristics. The friction force on the Belleville washer may range from between 0 lb. to about 1200 lb. depending in part on the distance between the wall  398  and the outer clutch plate  396 , which determines the amount by which the Belleville washer is compressed. At the pedals, the breakfree torque can range from about 344 in.-lb. to about 444 in.-lb., in one example. The specifications of one embodiment of the Belleville washer that works with embodiments of the invention are: OD=55.8 mm; ID=28.6 mm; Thickness (uncompressed)=2 mm; 830 (+/−20) lb. at 75% compression; 1110 (+/−30) lb. at 100% compression; Material=SAE 1075. 
     Similar to the embodiment illustrated in  FIG. 5   a,  the outer clutch plate collar  392  includes a hollow cylindrical main body  410  with internal threads at one end for engagement with the external threads on the outer end  412  of the axle housing  394 . The clutch plate collar  402  defines an outer radially extending engagement flange  414  attached to the outside end of the main body, and an inner radially extending flange, which is the inner clutch plate  396 , movably attached to the inside end of the cylindrical main body  410 . The inner clutch plate  396  is able to move axially (longitudinally) along all or a portion of the length of the cylinder main body  410  of the outer clutch plate collar  392 . 
     As shown with reference to the embodiments of the invention illustrated in  FIGS. 7 ,  8 , and  9 , the inner flange  396  has a central bore  124  defining a plurality of radially inwardly extending keys  126 . Corresponding longitudinally extending slots  128  are formed on the surface of the cylindrical main body of the outer clutch plate collar  392  at its inner end, and extend at least partially along the length of the main body, to receive keys  126  and allow the inner flange to move (float) axially along the length of the cylindrical main body  410 , to the extent of the length of the slots. When the cylindrical main body  410  is threadedly connected to the axle housing  394 , the inner flange  396  is positioned so the keys  126  are slidably received in the slots, and the inner flange  366  is retained on the end of the cylindrical main body  410  by the axle housing  394 . The intersection of the keys in the slots make the inner flange turn with the cylindrical main body. 
     It is contemplated that these free wheel clutch mechanism structures described herein could be mounted on the drive sprocket of the drive train, in addition to the slave sprocket of the drive train. It is also contemplated that a one-way bearing need not be used in all circumstances, in which case the clutch mechanism would be caused to slip if the break-free force threshold was reached in either the forward or rearward drive-train direction. 
     Embodiments of the present invention and many of its improvements have been described with a degree of particularity. The previous description is of examples for implementing the invention, and the scope of the invention should not necessarily be limited by this description. The scope of the present invention is defined by the scope of the following claims. 
     It is contemplated that these free wheel clutch mechanism structures described herein could be mounted on the drive sprocket of the drive train, in addition to the slave sprocket of the drive train. It is also contemplated that a one-way bearing need not be used in all circumstances, in which case the clutch mechanism would be caused to slip if the break-free force threshold was reached in either the forward or rearward drive-train direction. 
     Various embodiments of the present invention and many of its improvements have been described with a degree of particularity. The previous description is of examples for implementing the invention, and the scope of the invention should not necessarily be limited by this description. The scope of the present invention is defined by the scope of the following claims.