Abstract:
A stable vehicle that can be folded or disassembled, for example for transportation by another vehicle or for storage, without requiring the use of hand tools. Two front wheels carried by steerable forks, in combination with an underslung main frame, provide a stable configuration. When folded or disassembled, the vehicle is compact, and can be transported using car mounted racks designed for conventional bicycles.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/517,134, filed Nov. 3, 2003, the entire disclosure of which is hereby incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention is related to human powered vehicles. In particular, the present invention is directed to a stable vehicle that can be disassembled for transport by another vehicle. 
   BACKGROUND OF THE INVENTION 
   Human powered vehicles, such as bicycles, are popular as a means of transportation and recreation. However, bicycles can be difficult or impossible to ride for persons having difficulty with balance or motor control. Tricycles, including tricycles for adult riders, can provide a usable alternative to bicycles for such persons. 
   Conventional adult tricycles often feature a single front wheel in combination with two rear wheels. However, such designs can be unstable during cornering or other maneuvers. Designs using two front wheels in combination with a single rear wheel have been developed. However, such designs have typically consisted of modifications to conventional bicycles. Accordingly, such designs have suffered from a high center of gravity. 
   In addition to having limitations in handling and stability, conventional adult tricycles have been difficult to transport and store. For example, adult tricycles have not been easily transportable using conventional racks for mounting bicycles to a car. 
   SUMMARY OF THE INVENTION 
   In accordance with embodiments of the present invention, a vehicle with three or more wheels and having a relatively low center of gravity is provided. In particular, the rider is placed in a recumbent or semi-recumbent position. Furthermore, the front frame is interconnected to the main frame at a main frame riser, such that a longitudinal member of the main frame is relatively close to the ground. This allows the front wheels to be interconnected to the front frame using conventional bicycle forks, while maintaining a low center of gravity. 
   In accordance with embodiments of the present invention, a tricycle having two front wheels and a single rear wheel is provided. The frame may provide two separable assemblies: a main frame and a front frame. In accordance with other embodiments of the present invention, the front frame is hinged with respect to the main frame. When the tricycle is assembled, at least a top support structure of the front frame is substantially transverse to the main frame. Furthermore, the front frame or portions of the front frame are movably and/or removably interconnected to the main frame, to allow the front frame or portions of the front frame to be positioned such that they are substantially parallel to the main frame for transport, for example by car. In particular, when so disassembled, a vehicle in accordance with embodiments of the present invention can be carried by a conventional trunk mounted bicycle carrier rack. 
   In accordance with additional aspects of the present invention, a steering assembly featuring a handlebar having an axis of rotation that is within an angle of from about 0 to about 45° to the plane of the ground is provided. This feature allows the rider to easily turn the handlebars through their entire range of motion. The handlebars turn both front wheels through a linkage mechanism. In accordance with embodiments of the present invention, the linkage mechanism can be disconnected and reconnected without requiring the use of tools, to facilitate transportation or storage of the vehicle. In accordance with other embodiments of the present invention, the linkage mechanism does not need to be disconnected when the vehicle is configured for transportation or storage. 
   Additional features and advantages of the present invention will become more readily apparent from the following description, particularly when considered in view of the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a front perspective view of a vehicle in accordance with embodiments of the present invention; 
       FIG. 1B  is a front perspective view of a vehicle in accordance with other embodiments of the present invention; 
       FIG. 2A  is a rear perspective view of a vehicle in accordance with embodiments of the present invention; 
       FIG. 2B  is a rear perspective view of a vehicle in accordance with other embodiments of the present invention; 
       FIG. 3A  is a view of a vehicle in accordance with embodiments of the present invention that has been disassembled and attached to a rack for transportation by car; 
       FIG. 3B  is a front perspective view of the vehicle of  FIGS. 1B and 2B  in a folded condition; 
       FIG. 4  is an elevation of a vehicle in accordance with embodiments of the present invention, with the right front wheel and fork removed; 
       FIG. 5  is a front elevation of a vehicle in accordance with embodiments of the present invention; 
       FIG. 6A  is a top view of a steering mechanism in accordance with embodiments of the present invention; 
       FIG. 6B  is a front view of the steering mechanism of  FIG. 6A ; 
       FIG. 7A  is an illustration of a fastening assembly and cable arrangement in accordance with embodiments of the present invention; 
       FIG. 7B  is a perspective view of a fastening assembly and cable arrangement in accordance with other embodiments of the present invention; and 
       FIG. 8  is an illustration of a crankset carrier in accordance with embodiments of the present invention. 
   

   DETAILED DESCRIPTION 
   With reference now to  FIGS. 1A and 1B , vehicles  100   a  and  b  in accordance with embodiments of the present invention are shown in perspective views. As shown in the figures, a vehicle  100  may include a substantially longitudinal main frame  104 , comprising at least one longitudinal member  106 , interconnected to a front frame  108 . Interconnected to the main frame are a seat  112  for supporting a human user or rider, a rear wheel  116 , and a crank assembly  120 . In addition, the main frame  104  includes a riser structure or portion  124 . 
   The front frame  108  is interconnected to the main frame  104  by a fastening assembly  128 . More particularly, the fastening assembly  128  may interconnect a top support structure  110  included as part of the front frame  108  to the riser portion  124  of the main frame  104  such that at least the top support structure  110  of the front frame  108  is substantially perpendicular to the longitudinal member  106  of the main frame  104  when the vehicle  100  is ready for use by a rider. In accordance with an embodiment of the present invention, the fastening assembly  128  can be operated without requiring the use of hand tools. Accordingly, the front frame  108  may be folded with respect to or disconnected from the main frame  104 , for example for transportation of the vehicle  100  by another vehicle or for storage of the vehicle  100 . More particularly, the fastening assembly  128   a  depicted in  FIG. 1A  permits the front frame  108   a  to be fixed to the main frame  104   a  so that the vehicle  100   a  is ready to be ridden, and permits the front frame  108   a  to be disconnected from the main frame for storage or transport of the vehicle. The fastening assembly  128   b  depicted in  FIG. 1B  permits a first arm  130   a  and a second arm  130   b  of the front frame  108   b  top support structure  110  to be locked in a position that is substantially transverse to the main frame  104   b  when the vehicle  100  is being ridden and permits the arms  130  of the top support structure  110   b  to be rotated about hinges when locking mechanisms associated with the fastening assembly are released or unlocked, so that the first and second arms  130  are substantially parallel to the main frame  104   b , as described in greater detail elsewhere herein. 
   The front frame  104  includes a pair of wheel forks  132 . According to an embodiment of the present invention, the wheel forks  132  are conventional bicycle forks. As shown in the embodiment depicted in  FIG. 1B , the wheel forks  132   b  may comprise suspension forks to increase the comfort of the rider as compared to embodiments featuring a rigid fork  132   a  (as shown in FIG.  1 A). The wheel forks  132  may be pivotally mounted to the front frame  108  using a conventional bicycle headset  136 . A front wheel  138  is carried in each of the wheel forks  132 . 
   A steering mechanism  140  for receiving steering control inputs from a rider generally includes handlebars  144  pivotally mounted to the riser  124  of the main frame  104  through a steering pivot  148 . The steering pivot  148  may in turn be interconnected to a steerer or pivot plate  152 . A pair of tie rods  156  are provided so that a tie rod  156  extends between the steerer plate  152  and a steering arm  160  fixed to each wheel fork  132 . 
   Front wheel brakes  164  may be operated simultaneously through a central cable or straddle hanger  168 . The central cable hanger  168  may be interconnected to a brake lever  170  mounted to the handlebar  144 . In order to facilitate the removal of the front frame  108  from the main frame  104 , embodiments such as illustrated in  FIG. 1A  may include a tensioning knob  172  that can be operated to relieve tension on the central cable hanger  168 , so that the central cable hanger  168  can be disconnected from the individual front wheel brakes  164 . In accordance with embodiments of the present invention, this operation can be completed by the hand of a user, without requiring the use of tools. In accordance with embodiments such as illustrated in  FIG. 1B , cable housing stops  173  may be included as part of the fastening assembly  128 , allowing flexible cable housings  174  to be used to route the front brake cables between the fastening assembly  128  and the front frame  108 , eliminating the need to disconnect the central cable hanger  168  in order to fold the vehicle  100 . 
   With reference now to  FIGS. 2A and 2B , vehicles  100  in accordance with embodiments of the present invention are shown from a rear perspective view. As shown, the steering pivot  148  has an axis of rotation that is substantially parallel to the plane of the surface on which the vehicle  100  rests. In accordance with other embodiments of the present invention, the axis of rotation of the steering pivot  148  is at an angle to the plane of a road or other support surface on which the wheels  116 ,  138  of the vehicle  100  are resting of between 0 and 45°. In accordance with further embodiments of the present invention, the axis of rotation of the steering pivot  148  is at an angle of between about 1° and 20° from the plane of a support surface, with the rear of the steering pivot  148  farther from the plane of or through the support surface than the front of the steering pivot. As used herein, the plane of the support surface may be taken to mean the plane that is tangent to the bottom of all the wheels  116 ,  138 , and therefore may correspond to the ground the vehicle  100  is resting on when it is being ridden. This configuration allows a rider to steer the vehicle  100  easily, even when making tight turning maneuvers. For purposes of the present invention, an angle is about equal to a stated angle if it is within ±2° of the stated angle. 
   The crank assembly  120  includes pedals  204 , each of which are interconnected to the crank arms of a crankset  208 . The crankset  208  may be a conventional bicycle crankset. With particular reference now to  FIG. 2A , A forward drive chain  212  interconnects the crankset  208  to an input sprocket  216  of an intermediate or transfer gear set  220 . Tension may be maintained in the forward drive chain  212  by a spring-loaded tension pulley mechanism  224 . 
   The intermediate gear set  220  may include one or more output sprockets  228 . The output sprockets  228  are driven by a spindle interconnecting the output sprockets  228  to the input sprocket  216 . A rear drive chain  232  interconnects the output sprockets  228  to a freewheel  236  located on the hub of the rear wheel  116 . The rear drive chain  232  may be selectively located on different output sprockets  228  or cogs of the freewheel  236  by conventional bicycle derailleurs, to provide user selectable gearing. Alternatively or in addition, user selectable gearing may be provided through the use of an internally geared hub. As yet another alternative, a single gear ratio may be provided. 
   With particular reference now to  FIG. 2B , a single drive chain  240  may be used to interconnect the crankset  208  to a freewheel  236  on the hub of the rear wheel  116 . The drive chain  240  may be selectively located on different chainwheels provided as part of the crankset  208  or cogs of the freewheel  236  by conventional bicycle derailleurs, to provide user selectable gearing. Alternatively or in addition, user selectable gearing may be provided through the use of an internally geared hub. As yet another alternative, a single gear ratio may be provided. A chain guide assembly  242  with one or more idler pulleys  244  may be provided to limit chain slap. A vehicle  100   b  in accordance with embodiments of the present invention may also feature a suspended rear wheel  116 . Accordingly, in an exemplary embodiment, a swing arm  248  may be provided that is interconnected to the main frame  104  through a pivot point  252  and a spring/shock unit  256 . 
   With reference now to  FIG. 3A , a vehicle  100   a  in accordance with embodiments of the present invention is shown with the front frame  108  disconnected from the main frame  104 . In particular, the front frame  108  and the main frame  104  have been positioned so that the top support structure  110  of the front frame  108  and the longitudinal member  106  of the main frame  104  are substantially parallel to one another, thereby providing a more compact package for transportation or storage of the vehicle  100 . As used herein, substantially parallel may be taken to mean that at least portions of the referenced components lie in planes that are within about ±15 degrees of being parallel to one another. As shown in  FIG. 3 , by arranaging the front frame  108  and the main frame  104  so that they are substantially parallel to one another, the vehicle  100  can be loaded onto a conventional rack  304  mounted to the trunk of an automobile  308 . 
   With reference to  FIG. 3B , a vehicle  100   b  in accordance with other embodiments of the present invention is shown, with the front frame  108  folded. In particular, the first arm  130   a  and the second arm  130   b  of the front frame  108  have been rotated about hinges provided as part of the fastening assembly  128 , so that the arms  130  are substantially parallel to the main frame  104 , for example at least when the vehicle  100  is viewed from above. With respect to such an embodiment, no pieces of the vehicle  100  are required to be disconnected from the rest of the vehicle  100 . In addition, the front wheel brakes  164  can remain connected to the associated brake lever  170 . In particular, movement between the first and second arms  130  of the front frame  108  relative to the fastening assembly  128  is accommodated by the flexible cable housings  174 . In addition, it can be appreciated that the steering mechanism  140  does not need to be disconnected in order to fold the arms  130  of the front frame  108  in such an embodiment. In particular, it can be appreciated that each arm  130  and tie rod  156  pair, together with the steerer plate  152  and the associated steering arm  160 , form a parallelogram such that the tie rod  156  folds with its associated arm. Furthermore, it can be appreciated that as an arm  130  and associated tie rod  156  are folded, the orientation of the associated front wheel  138  remain about the same. That is, if the front wheels  138  are substantially parallel to the main frame  104  before folding the arms  130 , the wheel will remain substantially parallel to the main from  104  after folding the arms  130 . Furthermore, embodiments of the present invention allow the front wheels  138  to be steered using control inputs provided through the handlebars  144 , even while the vehicle is folded. 
   With reference now to  FIG. 4 , a vehicle  100  in accordance with embodiments of the present invention is shown in a side elevation, with the right front wheel  138  removed. As seen in  FIG. 4 , the main frame  104  is relatively low to the ground, facilitating a low center of gravity. 
   The main frame  104  may include a crankset carrier  404 . The crankset carrier  404  allows the position of the crankset  208  to be altered, to help accommodate riders of different sizes. Alternatively, the crankset  208  may be carried by a fixed bottom bracket tube or shell. Furthermore, it can be seen that embodiments of the present invention locate the crankset  208  substantially between the front wheels  138 . In accordance with further embodiments, the position of the seat  112  can be altered to change the relationship of the seat  112  to the handlebars  144  and the crankset  208 , again to accommodate riders of different sizes. In accordance with embodiments of the present invention, the seat  112  can be removed without requiring the use of tools, to facilitate storage and/or transportation of the vehicle  100 . 
   With reference now to  FIG. 5 , a vehicle  100  in accordance with embodiments of the present invention is shown in a front elevation.  FIG. 5  illustrates the relatively wide and therefore stable stance provided by embodiments of the present invention. In addition,  FIG. 5  illustrates how embodiments of the present invention provide a front frame  108  with a top support structure  110  to allow conventional bicycle forks  132  to be used to locate the front wheels  138 , while maintaining a relatively low center of gravity. Furthermore, it can again be seen that embodiments of the present invention locate the crankset  208  substantially between the front wheels  138 . In addition, the crankset  208  may be located so that it is lower than the top of the front wheels  138 . In accordance with still other embodiments of the present invention, the spindle of the crankset  208  may be about the same distance (i.e., within about ±1 inch) from the ground as the hubs of the front wheels  138 . Also, it can be seen that a top surface  504  of the top support structure  110  is above the front wheels  138 . 
   With reference now to  FIG. 6A , details of a steering mechanism  140   a , for use in connection with a vehicle  100  in accordance with embodiments of the present invention are shown from a top view. Details of the steering mechanism  140  are shown in  FIG. 6B  from a front view. As seen in  FIGS. 6A and 6B , the handlebars  144  are interconnected to a steerer or pivot plate  152  through or about the steering pivot  148 . The steerer plate  152  provides mounting points for a pair of tie rods  156 . Each tie rod  156  is interconnected to a steering arm  160  at an end of each tie rod  156  opposite the steerer plate  152 . Ball joints  608  may be provided at the ends of the tie rods  156  to interconnect them to the pivot plate  152  and steering arms  160  and to allow relatively free and unrestricted movement of the tie rods  156  relative to the steerer plate  152  and the steering arms  160 . In accordance with embodiments of the present invention, hand operable fasteners allow components of the steering mechanism  140  to be disconnected from one another, to facilitate the removal of the front frame from the main frame  104 . For example, wing nuts or knobs  612  may be provided to allow the tie rods  156  to be disconnected from the steerer plate  152 , without requiring the use of tools. Alternatively, in accordance with further embodiments of the present invention and as described elsewhere herein, the arms  130  of the front frame  108  can be folded without requiring disassembly of the steering mechanism  140 . 
   With reference now to  FIG. 7A , a fastening assembly  128  in accordance with embodiments of the present invention is illustrated. As seen in  FIG. 7A , the fastening assembly  128  may include one or more fastening subassemblies  704 . The fastening subassemblies  704  maintain the position of the main frame  104  relative to the front frame  108  when the vehicle  100  is in an assembled state. Furthermore, the fastening subassemblies  704  can be operated without requiring the use of tools to allow the front frame  108  to be removed or disconnected from the main frame  104 . For example, as shown in  FIG. 7A , hand operable knobs  708  may be threaded to bolts  712  that pass through holes formed in the main frame  104  and front frame  108 . The bolts  712  may be threaded into nuts  716  fixed to the main frame  104 . As can be appreciated by one of skill in the art, by providing a mechanical interconnection between the main frame  104  and the front frame  108  that is suitably configured, forces on the fastening assembly  128  when the vehicle  100  is in an assembled state can be kept relatively low. For example, as shown in  FIG. 7A , the main frame  104  may provide top  720  and bottom  724  brackets or fixtures separated from one another by a distance that is substantially equal to the distance between a top rail  728  and bottom rail  732  of the front frame  108  top support structure  110 . Accordingly, the relationship between the main frame  104  and the front frame  108  in a vertical direction can be precisely and reliably determined and maintained. In addition, the relationship between the main frame  104  and the front frame  108  from side to side can be determined by the position of the holes through which the bolts  712  are passed. Accordingly, forces in a side-to-side direction can be borne mainly by the bolts  712 , and the knobs  708  or other hand operable fasteners need not be required to resist large forces when the vehicle  100  is in normal operation. 
   Also illustrated in  FIG. 7A  (and in  FIG. 7B ) is the central cable hanger  168 . The cable hanger  168  is interconnected to the brake lever  170  by a primary brake cable  736  via a fastener  740 . The hanger portion  744  of the cable hanger  168  carries a secondary brake cable  748  at a center portion of the secondary brake cable  748 . The secondary brake cable  748  is interconnected to a first front wheel brake  164  at or towards a first end of the cable  748 , and the secondary brake cable  748  is interconnected to a second wheel brake  164  at or towards a second end of the cable  748 . This configuration allows a single brake lever  170  to apply equal braking force to each front wheel. 
   In addition, the brake actuation arrangement shown in  FIG. 7A  facilitates the disassembly of the vehicle  100 . In particular, by de-tensioning the brake cables  736  and  748 , the secondary brake cable  748  can be disconnected from the straddle hanger  168  without requiring the use of tools. In order to de-tension the brake cables  736  and  748 , a traveling brake cable housing stop  752  may be moved closer to stationary brake cable housing stops  756 . For example, as illustrated in  FIG. 7A , a tensioning knob  172  fixed to a threaded rod or bolt  764  may be turned to alter the distance between the traveling brake cable housing stop  752  and the stationary cable housing stops  756 . 
   With reference now  FIG. 7B , a fastening assembly  128  in accordance with other embodiments of the present invention is illustrated. In particular, the fastening assembly  128  is shown with the arms  130  of the front frame  108  folded so that they are substantially parallel to the main frame  104 . Accordingly, the fastening assembly  128  depicted in  FIG. 7B  comprises a folding assembly  750 . In general, the folding assembly  750  includes first  754   a  and second  754   b  connector plates that are fixed to the first  130   a  and second  130   b  arms of the front frame  108  respectively. Each connector plate  754  includes a hinged end  758  and a fixable end  760 . The connector plates  754  are interconnected to first  762   a  and second  762   b  fixed plates of the folding assembly  750  by hinge pins  766 . The fixed plates  762  may feature shoulders  788  that cooperate with connector plate flanges  792  to assist in locating the connector plates  754  when locked in an operating position by the locking assemblies  770 . 
   In addition, embodiments of a fastening assembly  128  comprising a folding assembly  750  may include first  770   a  and second  770   b  locking assemblies. In general, when the front frame  108  is folded, the locking assemblies  770  are released to allow the connector plates  754  to pivot about the binge pins  766 . Alternatively, when the vehicle  100  is in use, the locking assemblies  770  hold the connector plates  754  so that they are unable to rotate about the hinge pins  766 . In accordance with embodiments of the present invention, and as illustrated in  FIG. 7B , the locking assemblies  770  may each comprise a bolt  774  that can be received through a hole  778  in the first fixed plate  762   a . Each bolt  774  may pass through a bore  782  in the fixable end  760  of the connector plate  754 , and into or through a receiving hole  784  in the second fixed plate  762   b . The fixing member  774  may be fixed so that it maintains the connector plate  754  in a fixed position relative to the fixing plates  762  by being threaded into the receiving hole  784  itself, by passing through the receiving hole  784  and being interconnected to a threaded fastener  790 , such as a nut or a hand operated member, such as a knob or wing nut. Alternatively or in addition, the fixing member  774  may itself comprise a threaded bolt and may include a hand operable knob. As can be appreciated by one of skill in the art after consideration of the description provided herein, the locking assemblies  770  may alternatively comprise other structures capable of preventing a connecting plate  754  from rotating about the hinged end  758  when the vehicle  100  is in use. For example, locking assemblies  770  may comprise latches, spring loaded latches, cam type quick release levers or cotter pins. 
   With reference now to  FIG. 8 , a crankset carrier  404  in accordance with embodiments of the present invention is illustrated. As shown in  FIG. 8 , the crankset carrier  404  may include substantially parallel rail members  804  and  808 . One or both of the rail members  804 ,  808  may be integral to longitudinal members  106  of the main frame  104 , or may be interconnected to the main frame  104 . For example, as most easily seen in  FIG. 4 , the lower rail  804  may comprise an extension of a longitudinal member  106  comprising a bottom tube of the main frame  104 . The crankset carrier  404  additionally includes an adjustable bottom bracket  812 . The position of the bottom bracket  812  along the rails  804 ,  808  of the crankset carrier  404  can be altered by turning a screw or bolt  816 . In particular, the bolt  816  is interconnected to a threaded hole or holes provided as part of the bottom bracket  812 . Alternatively or in addition, fixing bolts  820  may be provided to clamp the bottom bracket  812  in a selected position along the rails  804 ,  808 . 
   As can be appreciated by one of skill in the art, various materials may be selected in the construction of a vehicle  100  in accordance with embodiments of the present invention. For example, square and/or round section tubing may be selected in the construction of the main frame  104  and front frame  108 . Where appropriate, plates or angled members may also be used. Such tubes and members may be formed from steel, including mild steel or chrome molybdenum, aluminum alloys, titanium, magnesium or other metals. Alternatively, composite materials or plastics may be used. 
   As a nonlimiting example, a vehicle  100  in accordance with the present invention was constructed from round and square section chrome molybdenum tubing and plate, and welded and/or bolted together. The front wheel forks  132  were conventional bicycle forks, and were mounted to the front frame  108  using conventional bicycle headsets  136 . The front  138  and rear  116  wheels were standard spoked bicycle wheels. The steering mechanism  140  included tie rods  156  formed from partially threaded rod stock, with commercially available ball joints  608  at both ends. The steering pivot  148  was formed from steel rod and plate, and rotatably interconnected to the riser  124  of the main frame  104  using a conventional bicycle headset. Conventional handlebars  144  and brake levers  170  were used. 
   The front crankset  120  was a conventional bicycle crankset with arms reversed such that the drive train was on the left side of the main frame  104 . The crankset  120  was carried by a conventional bicycle bottom bracket bearing set held in a bottom bracket shell provided as part of the bottom bracket  812 . The intermediate crankset  216  included sprockets from bicycle cranksets on either side of the frame  104 . Gearing was provided using conventional bicycle derailleurs controlled by levers mounted to the handlebars  144 . 
   Continuing the foregoing example, the wheel base was about 50 inches, the length about 76 inches, and the total width about 42 inches. The front wheel track was about 37 inches, and 26 inch wheels were used. The seat was positioned about 21½ inches from the ground. This configuration was found to provide good control even at speeds up to about 20 mph. The crankset carrier  404  provided about 5½ inches of adjustment, and the seat about 3 inches of adjustment, from front to rear. 
   As another non-limiting example, vehicle  100  in accordance with the present invention was constructed from elliptical section aluminum alloy tubing and aluminum alloy plate, welded and/or bolted together. The front wheel forks  132  were conventional suspension bicycle forks and were mounted to the front frame  108  using conventional bicycle headsets  136 . In addition, the rear wheel  116  was mounted to a swing arm interconnected to the main frame  104  through a pivot point and a spring/shock unit. Accordingly, a vehicle  100  may comprise a tricycle having all three wheels suspended using spring and shock units that are separately provided and/or integrated into forks or other components to provide a more comfortable ride. The wheels had a diameter of 20 inches, facilitating a compact design. 
   Continuing this second example, the front crankset  120  was a conventional bicycle crankset mounted into a conventional bicycle bottom bracket bearing set held in a bottom bracket shell. Furthermore, a single drive train was used to transmit drive force from the crankset  120  to the sprocket of the rear wheel  116 . Variable gearing was provided using conventional bicycle derailleurs. The seat  112  can be moved along a track to a selected position by operating a spring loaded latch. Also, the seat  112  can be completely removed for transport. 
   As can be appreciated by one of skill in the art after consideration of the description provided herein, it can be appreciated that various dimensions of a vehicle  100  may be selected in order to accommodate riders within particular size ranges, and/or different uses or applications of a vehicle  100 . Furthermore, although various embodiments have depicted vehicles  100  comprising tricycles, the present invention is not so limited. For instance, four-wheeled vehicles may be provided. In accordance with a four-wheeled vehicle  100 , the rear wheels may be interconnected to the main frame through an arm or arms that can be disconnected or moved with respect to the main frame to facilitate storage or transportation of the vehicle. 
   Although certain examples of a vehicle  100  in accordance with embodiments of the present invention have been given in the context of a vehicle  100  sized for adults, it should be appreciated that the present invention is not so limited. In particular, a vehicle in accordance with the present invention sized for children may be provided. In addition, the present invention is not limited to vehicles powered by the legs of a user. For example, motors or hand-operated cranks may be used instead of or in addition to leg powered cranks. 
   The foregoing discussion of the invention has been presented for purposes of illustration and description. Further, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, within the skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain the best mode presently known of practicing the invention and to enable others skilled in the art to utilize the invention in such or in other embodiments and with various modifications required by their particular application or use of the invention. It is intended that the appended claims be construed to include the alternative embodiments to the extent permitted by the prior art.