Abstract:
An all terrain vehicle, also known as an ATV, has a seat designed to comfortably accommodate a rider over a wide variety of rugged terrain. The seat is profiled so that the rider may easily shift body weight and lean with the vehicle while traversing steep and uneven terrain. The seat has a dip and taper positioned beneath a riders&#39; knee and lower thigh to provide the profile. The ATV is also provided with front fenders and mud flaps to protect the rider from debris. The fenders rotate with the wheel to provide the rider with maximum wheel visibility and access. The fenders can also be releasable, thereby rotating around the axis of rotation of the front wheels to break free from obstacles and provide easy access to the wheels beneath the fender. The ATV provides exceptional rider comfort and control.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The invention relates to a wheeled vehicle adapted to traverse a variety of terrain. The invention particularly relates to straddle-type vehicles commonly known as sport all terrain vehicles or sport ATVs. 
     2. Description of Related Art 
     ATVs have become very popular consumer products in recent years. These vehicles are typically used by one rider to travel undeveloped terrain, often called “off-road” connoting the lack of paved or even defined paths. ATVs are used for both off-road work and recreation. Due to the off-road use, ATVs commonly encounter obstacles such as rocks, steep hills, and ditches and may travel over loose, granular fill, unstable mud or shallow water. 
     To accommodate the different, and often rugged, terrain, such vehicles are generally designed with a powerful drive system to enhance mobility and traction and provide sufficient force to push or pull various objects. Additionally, as these vehicles may be required to travel over or under obstacles, ATVs are typically designed to be as compact and light-weight as possible to allow a rider to maneuver the vehicle in difficult circumstances. In some cases, a rider must manually move or free the vehicle by pushing, pulling or tipping the vehicle. 
     In prior ATVs, certain elements have been added in response to the above noted problems and conditions faced by the vehicle and its rider. For example, fenders and mud flaps are typically provided to shield the rider from spray of debris and mud. However, such fenders can obscure the rider&#39;s view of the wheels, thus inhibiting the rider&#39;s ability to avoid or assess obstacles. Also, fenders sufficiently sized to protect a rider often interfere with ground obstacles and become damaged or break off. Additionally, fenders tend to collect mud and debris, which can accumulate above the wheel eventually interfering with rotation of the wheel. 
     Protective covers may also be provided over the engine compartment to shield the engine from debris and damage. The front of the vehicle, in particular, may be provided with protective coverings over the radiator, the head lamps, and the control elements, for example. 
     At times due to the conditions encountered off-road, it may be desirable or necessary to physically move the vehicle. To assist riders in manually moving the ATV, many prior vehicles have grab bars located on the vehicle. However, these grab bars must be securely attached to a frame member and cannot protrude too far from the vehicle, lest the bar interfere with its operation. 
     As a result of traversing such rugged terrain, the rider is often subjected to an uneven or unbalanced ride. It may be necessary, depending on the inclination of the vehicle or slope of the terrain, for the rider to balance the vehicle by shifting his or her body weight or leaning against the tilt of the vehicle. Often, riders must clamp onto the seat or body of the ATV with their legs to maintain control and remain astride the vehicle. 
     Additionally, the rider, who straddles the vehicle and rides on an open seat, often experiences a rough ride, which can cause discomfort during lengthy expeditions. In particularly rough terrain, a rider tends to get jostled. Such vehicles should provide adequate suspension to comfort the rider and allow the rider to remain on the vehicle over most terrain. 
     Another problem encountered by an ATV when traveling on uneven or sloped terrain is continuous engine operation. When an ATV is tilted or even tipped on its side, engine operation can be compromised or interrupted if flow of required engine fluids is prevented. For example, a gravity oil feed system must be oriented substantially vertically to operate. When an ATV with gravity oil feed is tipped on its side, oil will not be properly supplied to the other engine components seriously compromising engine performance and durability. 
     Accordingly, stability and ease of operation with a high degree of control is important for both engine performance and rider comfort. 
     SUMMARY OF THE INVENTION 
     An aspect of the embodiments of this invention is to provide a stable vehicle that is able to traverse a wide range of off-road conditions. 
     Another aspect is to protect the rider of the all terrain vehicle from debris without compromising performance by obscuring visibility or interfering with obstacles. 
     A further aspect is to provide a versatile yet stable seating arrangement to allow a rider improved control and comfort while seated. 
     An additional aspect is to assist the rider in maneuvering the vehicle in a variety of conditions. 
     According to embodiments of this invention, a vehicle is provided that has a frame with a front portion, a rear portion, a lower portion and an upper portion, and a plurality of wheels supported for rotation by the frame, including at least one front wheel and at least one rear wheel. A contoured seat is provided for a rider supported by the upper portion of the frame. The seat has a profile including a central section having a first height with respect to a horizontal support surface and an end section having a second height with respect to the horizontal support surface. The first height is less than the second height. The seat is tapered from a wide end toward a narrowed section that coincides with the central section. 
     A drive assembly is supported by the frame and includes an engine and a drive system connected to at least one of the wheels to impart drive power to the at least one wheel. A vehicle control assembly is also provided and includes a steering mechanism supported by the frame and connected to the at least one front wheel to turn the at least one front wheel about a vertical axis, a power controller connected to the engine to control the drive power imparted by the drive system, and a braking mechanism connected to at least one of the wheels to inhibit rotation of the at least one wheel. 
     Also according to the aspects of embodiments of this invention, a vehicle is provided that includes a frame with a front portion, a rear portion, a lower portion and an upper portion, and a plurality of rotatable wheels, each wheel connected to a wheel support coupled to the frame, including at least one front wheel and at least one rear wheel. A fender is positioned over the at least one front wheel, and a fender support is coupled to the fender and supported by the wheel support. A seat for a rider is supported by the upper portion of the frame. A drive assembly is supported by the frame and includes an engine and a drive system connected to at least one of the wheels to impart drive power to the at least one wheel. 
     A vehicle control assembly is also provided that includes a steering mechanism supported by the frame and connected to the wheel support of the at least one front wheel to turn the at least one front wheel about a vertical axis, a power controller connected to the engine to control the drive power imparted by the drive system, and a braking mechanism connected to at least one of the wheels to inhibit rotation of the at least one wheel. When the at least one front wheel is turned by the steering mechanism, the fender that is supported by the wheel support is turned about the same vertical axis with the at least one front wheel. 
     Preferably, the vehicle is a light-weight all terrain vehicle. The seat is preferably a straddle-type seat. Additionally, the preferred number of wheels includes two front wheels and two rear wheels. 
     Another aspect of this invention is to provide various additional features that are usable in combination on one vehicle, individually usable on separate vehicles or selectively combined on various vehicles, including different types of vehicles, such as vehicles with different wheel and seating configurations. 
     For example, an open U-shaped foot peg with a serrated edge can be provided to provide a strong, stable foot support that inhibits the accumulation of mud and debris on the foot peg. 
     A convex cover can be provided over the front of the vehicle or portions of the front of the vehicle, such as the radiator. 
     A front and/or back grab handle can be provided as bumpers attached to the upper portions of the main frame or extended frame positioned close to seat level to allow easy access for manual maneuvering of the vehicle. 
     The frame and engine placement can provide a low center of gravity. The wheels can also be significantly offset from center. A large suspension travel can provide the rider with a more secure ride. 
     The frame can be formed of a pair of one piece tubular members bent to the desired support shape, which can reduce the required welds and corresponding potential points of weakness. 
     An oil tank with a generally fumnel shape and a sump portion can be used in a gravity feed system to reliably supply oil even when the vehicle is disposed at an angle. 
     These and other aspects of the invention will be apparent when taken in conjunction with the drawings and detailed description below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings that form part of this original disclosure: 
     FIG. 1 is a perspective view of a vehicle in accordance with this invention; 
     FIG. 2 is a front view of a vehicle in accordance with this invention; 
     FIG. 3 is a side view of a vehicle in accordance with this invention; 
     FIG. 4 is a back view of a vehicle in accordance with this invention; 
     FIG. 5 is another side view of a vehicle in accordance with this invention; 
     FIG. 6 is a top plan view of a vehicle in accordance with this invention; 
     FIG. 7 is an exploded perspective view of the frame in accordance with this invention; 
     FIG. 8 is a partial perspective view of the frame and seat in accordance with this invention; 
     FIG. 8A is a plan view of the seat of FIG. 8; 
     FIG. 9 is a partial exploded perspective view of the frame and rear suspension in accordance with this invention; 
     FIG. 10 is a partially exploded perspective view of the front of the frame in accordance with this invention; 
     FIG. 11 is an exploded partial view of the steering assembly and front fender in accordance with this invention; 
     FIG. 12 is an exploded perspective view of the front frame and suspension in accordance with this invention; 
     FIG. 13 is an exploded perspective view of protective covers and accessories in accordance with this invention; 
     FIG. 13A is a perspective view of an embodiment of the front fender in accordance with this invention; 
     FIG. 13B is a partial side view in cross section of an embodiment of the fender and fender support in accordance with this invention; 
     FIG. 13C is a partial side view in cross section of an embodiment of the fender and mudflap in accordance with this invention; 
     FIG. 14 is an exploded perspective view of the radiator, oil tank, gas tank and engine in accordance with embodiments of this invention; 
     FIG. 15 is another schematic view of an average rider with standard dimensional ranges; 
     FIG. 16 is a schematic view of an average rider similar to FIG. 15; 
     FIG. 17 is a perspective view of several components of the vehicle of the present invention, showing their positional relationship with respect to one another; 
     FIG. 18 is a perspective view of the oil tank of the vehicle of the present invention; and 
     FIG. 19 is a side view of the general design of the oil tank for the vehicle of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A vehicle in accordance with the embodiments of this invention is illustratively shown in FIG.  1 . The various elements described below are discussed for ease of explanation with reference to the vehicle  10  shown in the drawings. However, it will be understood by those skilled in the art that the various elements are usable, separately or in various combinations, on other types of vehicles. 
     Vehicle  10  is designed to comfortably accommodate an average rider  210 , which as shown in FIGS. 15 and 16 is a 50 th  percentile U.S. male with the range of dimensions shown on these drawings. Of course, in operation, a rider is any person that drives the vehicle and is not limited to the average size person  210  of FIGS. 15 and 16. 
     Vehicle  10  is preferably an all terrain vehicle used by a single rider. The vehicle is intended for recreation and, as described below, is designed to handle various terrain and conditions, particularly conditions termed “off-road”. Of course, the vehicle is not limited to the uses and conditions described herein. 
     As seen in FIGS. 1-6, vehicle  10  comprises a main frame  12  with two front wheels  14  and two rear wheels  16  rotatably supported by main frame  12 . The preferred configuration includes four wheels for enhanced stability. However, two or three wheel configurations are also possible. A drive system  18  is carried by main frame  12  and is preferably a relatively powerful system that delivers a high rate of torque to the front or back wheels of the vehicle as described below. The embodiment described herein uses a Rotax™ 650 engine, which is a 4 stroke, 1 cylinder double overhead cam shaft type. However, any suitable drive system could be substituted. 
     A seat  20  is supported by frame  12  for supporting a rider in a straddle position with a leg on each side of seat  20  supported by a foot rest  56 . Connected to main frame  12  is a steering assembly  22  including handle bars  24  for use by the rider. As is conventionally known and best seen in FIG. 6, handle bars  24  carry hand grips  26 , a front brake lever  28 , a clutch lever  30  and various other switches. Preferably, handgrips  26  are spaced at a distance A above a horizontal surface (when the vehicle is at full droop) in range of 1080-1195 mm (42.5-47 inches), for example 1138 mm (44.8 inches). Also, handle bars  24  are preferably angled rearwardly at an angle α of about 17°. Preferably, handle bars  24  have a horizontal spread in the range of 730-810 mm (28.7-31.9 inches), for example 770 mm (30.3 inches). 
     Referring to FIG. 7, main frame  12  is formed of two side frame pieces  32  and  34 , which connect together to form a cavity  36 . Each side frame piece,  34  for example, is preferably formed of a one piece tubular support that is bent into a polygon. The ends are connected at a common point to an intermediate support member  38 , thus creating one joint for each side frame piece. This configuration facilitates manufacturing by reducing the number of joints that must be welded or otherwise connected and creates a strong, rigid frame with minimal points of weakness. Of course, each side frame piece could be formed of a plurality of individual members connected together into a polygon if desired. 
     For additional rigidity and to resist buckling and enhance strength, additional support members, shown as  40  in FIG. 7, can be used as desired. The number of intermediate and additional support members depends on the particular strength requirements and materials used for the vehicle. Frame pieces and support members are also used, and added as necessary, as support for attachment of various elements such as the engine and/or covers. As seen in FIG. 7, brackets, such as  42 , are attached to the support members for attachment of other components of the vehicle as described below. 
     The frame members can be made of hollow pipes of steel, for example. The support members can be hollow pipes, flat straps, T-bars, channel members or I-beams depending on the strength, weight and cost parameters of the particular vehicle. 
     Side frame  32  is connected to side frame  34  by a series of spaced cross support members  44  that hold side frames  32 ,  34  in a fixed relationship with respect to each other and form cavity  36 . Supported between upper portion and lower portion of main frame  12  in cavity  36  is drive system  18 , mainly the engine, which is described below. The configuration of cross support members  44  varies depending on the location of the cross support members in the frame. In the vehicle shown in this example, the rear cross support members are tubular pipes, the top cross support members are I-beams, and the front, bottom cross support members are channel members. 
     The front of main frame  12  is generally triangular and slopes downwardly. The front of main frame  12  supports the front wheel assembly with cross support members  44  that, in this case, are four channel brackets  46  each extending outwardly from side frame pieces  32 ,  34 . As described below, another cross support member  44  is disposed above channel brackets  46 , also in the form of a channel bracket  48  extending outwardly from side frame pieces  32 ,  34 . A seat  50  that receives steering assembly  22  is created by a cross strap between channel brackets  46 . A pair of front bumper brackets  52  extend outwardly from the front portion of main frame  12  at the ends of intermediate support members  38 . 
     Lower portion of main frame  12  includes brackets for retaining portions of the drive system  18 , particularly the engine. Toward the rear portion of the lower portion of main frame  12 , a pair of tapered brackets  54  extend from each side frame piece  32 ,  34 . Each bracket supports a foot rest  56 . Each foot rest  56  is formed as an open generally U-shaped peg that has a series of serrations  58  pointing upwardly. In the bottom of each foot rest  56 , a series of openings  60  are provided. By this configuration, a rider can securely rest the foot with the serrations inhibiting slipping. The openings allow dirt and debris to fall through to the ground and discourage caking of mud and dirt in the foot rest  56 . Foot rest  56  may be formed from a single piece of metal shaped into a U by bending a plate of material with opposed serrated edges at two longitudinal fold lines with openings preformed or punched after folding. Alternatively, foot rest  56  may be formed by bending a strip of material with one serrated edge at two transverse fold lines, thus forming a loop with an open bottom. 
     The top surface of foot rest  56  is preferably spaced from a horizontal support surface at a distance B, in a range of about 380-420 mm (15.0-16.5 inches), for example 400 mm (15.7 inches) (when the vehicle is at full droop). Foot rest  56  is spaced below handle bars  24  at a distance C, in a range of about 700-775 mm (27.6-30.5 inches), for example 738 mm (29.1 inches). Foot rest  56  is positioned from the rear edge of handle bars  24  at a distance D, in a range of about 225-255 mm (8.86-10.0 inches), for example about 240 mm (9.45 inches). In addition, foot rest  56  is positioned from the rear wheel axle at a distance E, in a range of about 535-595 mm (21.1-23.4 inches), for example 566 mm (22.3 inches). 
     The rear portion of main frame  12  has a bracket  62  for supporting the rear wheel assembly and a bracket  64  for the suspension system. A frame extension  66  is attached to the rear portion of main frame as shown in FIGS. 7 and 8. Frame extension  66  forms a generally triangular shape when viewed from the side and has a pair of side arm supports  68  and  70  on each side. Cross arm supports  72  and  74  are provided to space the side arms from each other and to form a rigid frame assembly. Main frame  12  with frame extension  66  forms a generally rhomboidal frame unit. As seen in FIG. 8, brackets  76  are provided at the rear end of frame extension  66  to secure a rear bumper  78  thereto. 
     Rear bumper  78  is formed as a generally U-shaped handle and functions as a grab bar for a rider to pull or maneuver the vehicle manually when necessary. As seen in FIGS. 3-6, rear bumper  78  extends just beyond the rear wheels  16  to protect the vehicle from obstacles. Rear bumper  78  slopes downwardly to provide a rider with leverage when necessary to manually move the vehicle. Although shown as an attachment to frame extension  66 , rear bumper could be integrally formed with frame extension  66 . Similarly, frame extension  66  could be formed integrally with main frame  12 . 
     Referring to FIG. 8, the upper portion of main frame  12  and frame extension  66  form a support surface for seat  20 . The support surface is generally upwardly concave with the upper portion of main frame  12  and the upper portion of frame extension  66  meeting at an obtuse angle to form a V-shaped dip  80 . Seat  20  is contoured to follow and complement dip  80  thus forming an upwardly concave seating surface. Seat  20  is also inwardly tapered at dip  80  so that the rider can securely clamp the lower legs on either side of dip  80 . As seen in FIG. 8A, seat  20  has an inwardly tapered section  87  that coincides with dip  80 . A pair of side wings  89  extend forward from dip  80  and inwardly tapered section  87 . Side wings  89  are padded and form a clamping area for a rider&#39;s knees when a rider is shifted forward. 
     Seat  20  is formed of materials known for seating use on all terrain vehicles. Preferably, the seat is formed of a molded plastic contoured shell with a resilient, foam inner support member supported by the shell and a durable all weather outer surface covering, such as vinyl, formed over the resilient member. 
     As seen in FIG. 8, seat  20  can be secured with a hinge and latch onto the frame with a latch assembly  82  to provide access to the components beneath seat  20  if desired. Typically, access to the battery compartment is beneath the seat. Storage areas may also be provided. Resilient stoppers  84  prevent wear and rattle of seat  20  during operation. Of course, if desired, seat  20  can be fixed to the frame. 
     As seen in FIGS. 3 and 5, the contour of seat  20  provides for a central dip  80  portion that slopes gradually up to a raised portion  86  at the rear of the vehicle. The rear end of seat  20  is preferably higher with respect to a horizontal support surface than dip  80 . Also, rear portion  86  is preferably wider than tapered section  87 . The front end of seat  20  is also preferably a raised portion  88  that is higher with respect to a horizontal support surface than dip  80 . In the embodiment shown in FIGS. 3 and 5, front raised portion  88  is higher than rear raised portion  86 . Front raised portion forms a cushioned area that protects a rider from impact with the gas tank or steering assembly,along with cushioned side wings  89  that allow a rider to bear against the sides of vehicle  10 . 
     Front raised portion  88  is shown as an integral portion of seat  20 . However, if desired, front raised portion  88  could be a separate cushioned component. Similarly, side wings  89  are shown as integral extensions of seat  20 , but could be formed as separate cushioned or padded components. The relative vertical heights of the seat portions could also vary. For example, rear end of the seat could be level or tapered at the back so that the rear end is level with the dip portion. The relative taper can also vary, but it is desired that the tapered section be sufficiently narrow to allow a rider to sit comfortably and securely with the lower legs and knees straddling the vehicle. Preferably, tapered section  89  is about half as wide at the top of seat  20  than at the bottom of seat  20 . For example, the width of the tapered section can be about 5.5 inches at the top, with the bottom width being about 11.5 inches. 
     Seat  20  can also be provided with only a tapered section  87 , with no dip such that the side profile of the seat would be flat. Such a configuration would allow a rider to still clamp the sides of the seat while riding. Seat  20 , in either configuration, could also be used on other vehicles, including but not limited to personal watercraft, snowmobiles or motorcycles. 
     FIG. 3 shows an example of preferred dimensions of seat  20  in which front raised portion  88  slopes at an angle β, of about 42° (at rest) toward dip  80 . Rear raised portion  86  slopes upwardly at an angle γ from dip at an angle of about 7° at rest, and about 6° with a rider. 
     As seen in FIG. 8A, dip  80  coincides with a tapered area  89  of seat  20 . Preferably, seat  20  tapers inwardly. Dip  80  is positioned generally vertically above foot rests  56  and spaced slightly rearwardly. Dip  80  and taper section  89  are designed to support a rider at the knee and lower thigh with the foot supported on foot rest  56 . Thus, dip  80  is preferably spaced at a distance F, within about 130-145 mm (5.12-5.71 inches), for example 138 mm (5.43 inches) from foot rest  56  toward the rear of the vehicle. Likewise, dip  80  is preferably spaced at a distance G, in the range of about 445-495 mm (17.5-19.5 inches), for example about 471 mm (18.5 inches) above foot rests  56  to accommodate an average size rider. By this positioning, a rider is able to lean or slide sideward while riding to facilitate maneuvering the vehicle because the rider&#39;s knee is positioned slightly above the seat over dip  80 . Seat  20  has an intermediate height H in a range of about 470-520 mm (18.5-20.5 inches), for example about 497 mm (19.6 inches) above foot rest  56 . At its rear end, seat  20  also has a height I of about 495-550 mm (19.5-21.7 inches), for example 525 mm (20.7 inches) above foot rest  56 . A distance J, measured from foot rest  56  to the height of the intermediate portion of the seat is in the range of about 330-367 mm (13.0-14.4 inches), for example 349 mm (13.7 inches). At a distance of K, measured from foot rest  56  to the rear of seat  20 , is about 535-595 mm (21.1-23.4 inches), for example 566 mm (22.3 inches). 
     The rear suspension  90  is shown in detail in FIG.  9 . As can be seen in FIGS. 4 and 7, rear suspension  90  extends from the upper portion of main frame  12  to the rear wheel assembly. The suspension assembly, including rear suspension  90  and the front suspension described below, provides a very large vertical travel distance, preferably in the range of 11-12 inches of vertical travel, which results in a smoother, more stable ride for a user. In this case, rear suspension  90  provides a vertical travel distance of about 292 mm (11.5 inches). 
     Rear suspension  90  includes a shock absorber with a central hydraulic cylinder  92 , a piston  94  and compressed gas source  96  surrounded by a heavy duty helically wound spring  98 . The top end I  00  of the shock absorber is attached to bracket  64  on main frame  12  with a conventional fastener. The other, bottom end  102  of the shock absorber is attached to the rear wheel assembly, also with a conventional fastener at a swing arm  104 . Swing arm  104  is pivotally attached at end  106  to main frame  12  at bracket  62  and rotatably supports the rear wheel drive axle with a cylindrical support sleeve  108  that clamps around the rear axle, as seen in FIG.  4 . 
     Turning to the front portion of main frame  12 , FIG. 10 shows the front portion of main frame  12  that supports the front wheel assembly. Extending from each side frame piece  32 ,  34  are a pair of extension arms. For example, lower arm  110  and upper arm  112  extend from side frame piece  34  and are pivotally connected at channel brackets  46 . Similar extension arms extend from side frame piece  32  on the opposite side. 
     Each extension arm, lower arm  110  for example, is formed as a V-shaped support with each inner end of the arms  110   a  and  110   b  being connected to a channel bracket  46  and the vertex  110   c  being connected to a knuckle joint  114 . Referring to knuckle joint  114  in FIGS. 10 and 11 for ease of explanation, pivotal connection points  116  and  118  are provided for upper and lower extension arms and an outwardly extending axle  120  is provided for attachment to the hub  122  for one of the front wheels  14 . As seen in FIG. 10, a suitable fastener assembly including a series of o-rings, ball bearings, bushings, seals and nuts is provided to attach the wheel hub  122  to the axle  120  for rotation. 
     Referring to FIG. 11, each knuckle  114  is also connected to steering assembly  22  at flange  124 , which is fastened to steering tie rod  126 . A pair of tie rods  126  are fastened to base  128  and extend from steering assembly  22  adjacent steering column  130 . As steering column  130  is rigidly connected to base  128 , steering motion  30  actuated by handle bars  24  translates through column  130  and base  128  to tie rods  126 , which in turn pull or push knuckles  114  and the associated front wheel hub in the desired steering direction. 
     Front suspension  132  is shown in detail in FIG.  12 . Front suspension  132  is a shock absorber with a cylinder  134  and piston  136  surrounded by a helically wound heavy duty spring  138 . One end  140  of the shock absorber is pivotally fastened to main frame  12  at channel bracket  48 . The other end  142  of the shock absorber is pivotally attached to lower arm  110  adjacent vertex  110   c.  Front suspension  132  allows the front wheels to move vertically with respect to the frame and independently of each other to improve the ride and enhance stability. As discussed above, the suspension system of the vehicle of the preferred embodiment provides a wide range of vertical travel. In this case, front suspension  132  preferably has a vertical travel of about 305 mm (12.0 inches). 
     The front wheel hubs are widely set apart for increased stability. In the preferred embodiment, the span between the outer edges of front wheels is in the range of 1110-1230 mm (43.7-48.4 inches), for example about 1170 mm (46.1 inches). The rear wheel hubs are also set apart with the outer edges of the rear wheels being spaced within a range of 1205-1335 mm (47.4-52.6 inches), for example about 1270 mm (50.0 inches). The front wheel track from hub to hub is preferably within a range of 995-1100 mm (39.2-43.3 inches), for example about 1048 mm (41 in.) and the rear wheel track from hub to hub is preferably in the range of 940-1040 mm (37.0-40.9 inches), for example about 990 mm (39 in). Thus, the front wheel track is slightly larger than the rear wheel track. The axis of rotation of the front wheels  14  is spaced from the axis of rotation of the rear wheels  16  by a distance in the range of about 1250-1350 mm (49.2-53.1 inches), which also forms a stable wheel base. The ratio between the wheel base and the wheel tracks is roughly 1.3, which greatly enhances stability. The clearance beneath the frame at the front and under the engine as shown is about 279 mm (11 inches). The clearance under the drive train at the rear axle as shown is about 121 mm (4.75 inches). The wide set wheel base and wheel tracks, particularly coupled with the enhanced suspension system, adds to the stability of the vehicle. 
     Secured to each knuckle  114  is front fender assembly  144 . There is a front fender assembly  144  provided for each front wheel  14 . Front fender assembly  144  includes a fender  146 , a fender support  148  and an optional mud flap  150 . Fender  146  is a rigid sheet member, which is generally convex and shaped to generally complement a section of the outer edge of the front wheel. Fender  146  is supported by fender support  148 , which is a V-shaped support bracket having a pair of support arms fastened to either end of fender  146 . As seen in FIG. 11, fender assembly  144  is secured to the top edge  154  of knuckle  114  by a pair of fasteners that clamp bracket  156  onto knuckle  114 . Fender  146  is supported at a distance from the outer edge of the front tire to provide sufficient clearance for the front wheel to turn even when caked with mud and debris and/or when the inner side of fender  146  has an accumulation of debris. The front edge of fender  146  is positioned to provide a clear line of sight to the front edge of the front wheel for the rider, as seen in FIG.  5 . 
     Alternatively, fender assembly  144  may be pivotally attached to knuckle  114  to allow at least fender  146  to pivot with respect to the axis of rotation of the front wheel to provide access to the front wheel and to move away from ground obstacles. As seen in FIG. 13A, fender support  148  can be pivotally connected to knuckle  114  with a spring biased connector  158  that allows fender support  148  to pivot with respect to knuckle  114  along the axis of rotation of the front wheel. A spring may be used to bias the fender support into the normal operating position. FIG. 13A shows a simple hinge spring, but any biasing element may be used, including but not limited to a compression, coil or leaf spring or a rubber grommet assembly. 
     Also, rather than providing the pivotal connection at the knuckle  114 , fender  146  may be pivotally, releasably connected to fender support  148 . As seen in FIG. 13B, fender  146  may have a snap fit connection  160  that releasably connects to fender support  148 . A biasing member may be provided to return fender  146  to the operating position. 
     Mud flap  150  can be a separate element fastened to the rear edge of fender  146 , as seen in FIG. 13, or integrally formed with fender  146 . Mud flap  150  is preferably a flexible sheet made of a resilient, highly durable plastic material, such as vinyl. However, mud flap  150  may be formed of a rigid material. In this case, or even when resilient material is used, mud flap  150  can be fastened to fender  146  with a pivotal or releasable connection  152 , as seen in FIG.  13 C. The connection  152  can be spring loaded to allow mud flap  150  to pivot upwardly upon impact with an obstacle. Similarly, mud flap can be configured to break free from fender  146  if an obstacle is encountered. 
     In operation, due to the direct connection between the fender and the front wheel assembly  14 , fender assembly  144  turns with front wheels  14 . Thus, front fenders  146  rotate with knuckles  114  about a vertical axis. To accomplish this, it is not necessary that the fender support  148  necessarily be connected to knuckle  114  as long as a connection is made with the front wheel assembly  14  or steering assembly  22 , rather than rigidly with the frame. The effect of rotatable fenders is that the rider remains protected from flying debris at all times during operation. This greatly increases rider comfort and safety. 
     FIG. 13 also shows several of the protective components for vehicle  10 . Referring also to FIGS. 1-6, a front bumper  162  is secured to main frame  12  by flanges  164  that connect to brackets  52  at each side frame piece  32  and  34 . Front bumper  162  is generally U-shaped to form a grab bar that can be used by a rider to manually maneuver vehicle  10  if necessary. Front bumper  162  has side handles  166  that provide additional grasping portions. Front bumper  162  is preferably formed of a rigid tubular metal member for strength. A skid plate  168  is fastened to front bumper  162  as a protective plate for oncoming obstacles. Skid plate  168  can be formed of any durable material, preferably a rigid, molded plastic. As seen in FIGS. 3 and 5, front bumper  162  protrudes beyond the front edge of front wheels  14  for protection. 
     A front cowling  170  is positioned over the upper front portion of the vehicle to protect the rider and drive assembly, to improve the aerodynamics of the vehicle, and to provide an aesthetically pleasing appearance for the vehicle. Front cowling has a front convex portion with wings  172  extending from either side. Various front vents and an opening  174  that frames the head lamp are provided, as seen in FIGS. 1,  2 , and  13 . 
     Disposed behind steering assembly  22  and front cowling  170  is a gas tank cover  176  shaped to fit on top of and over both sides of the gas tank. Gas tank cover  176  slopes with the front portion  88  and side wings  89  of seat  20 . Gas tank cover  176  is shaped to fit around the steering column and provide access to the gas tank for filling. 
     A pair of foot protectors  178  are provided at each side of main frame  12  to shield a rider&#39;s foot from rear wheels  16 . Foot protectors  178  are disposed rearwardly of foot rests  56  and provide an additional support surface for a rider. A rear fender  180  is attached to the upper, rear portion of main frame  12  to cover rear wheels  16 . As shown, rear fender  180  extends under seat  20  with an opening  182  for access to the battery. Rear fender  180  is shown as a one piece unit, but may be made of individual components is desired. Mud flaps similar to mud flaps  150  may also be provided if desired. 
     Front cowling  170 , gas tank cover,  176 , foot protectors  178  and rear fender  180  are preferably formed of durable rigid sheet material, such as molded plastic, that has a high resistance to impacts and superior weatherability. 
     Finally, retained within main frame  12  is drive system  18 . As partially schematically represented in FIG. 14, the drive system  18  includes an engine  182 , a fuel system with a gas tank  184 , a cooling system with a radiator  186 , and a transmission with a drive train  188 , best seen in FIG.  4 . 
     Radiator  186  has a protective cover  196  fastened over the front face to protect radiator  186  from damage during operation. Cover  196  is outwardly convex and thus is spaced from the front face of radiator  186 . The convexity adds strength and stiffness to the sheet material of cover  196  and ensures that any small penetrations of cover  196  will not affect radiator  186 . Cover  196  has side edges  198  that have a flat edge to meet radiator  186  and a curved edge to match the outer surface that stiffen cover  196  and further protect radiator  186 . 
     As shown in greater detail in FIGS. 18 and 19, oil tank  190  is provided for the engine with a gravity feed arrangement. Oil tank  190  has a main chamber  192  formed in a generally funnel, tapered shape that leads to a sump  194 . The funnel shape is shown in general detail in FIG.  19 . The shape of oil tank  190  ensures that oil will be supplied to engine  182  when vehicle  10  is tipped at any angle from the horizontal. As oil is funneled to sump  194  in all but horizontal positions, oil delivery can be assured. 
     As shown in FIG. 17, oil tank  190  is positioned above gas tank  184 , behind radiator  186  and lighting fixture  200 . The arrangement of these elements in this manner provides a compact, yet efficient, arrangement. 
     Other conventional components of a drive system, such as an exhaust system, are provided as seen in the figures but need not be described in detail as one of ordinary skill in the art would readily recognize the remaining drive components. 
     All of the above noted dimensions are provided merely for purposes of description and are in no way intended to be limiting. The various parameters could of course be varied and remain within the scope of the invention. 
     The embodiments described herein are intended to be illustrative of this invention. As will be recognized by those of ordinary skill in the art, various modifications and changes can be made and would remain within the scope of the invention defined in the appended claims.