Abstract:
Each side of an adjustable handlebar assembly has a hand grip assembly receiving portion having one of an elongated hollow member and an elongated member, a hand grip assembly and at least one releasable fastener. The hand grip assembly has the other of the elongated hollow member and the elongated member, and a hand grip disposed on the other of the elongated hollow member and the elongated member. The at least one releasable fastener is disposed on one of the elongated hollow member and the elongated member. The elongated member is received coaxially in the elongated hollow member. The hand grip is axially movable and pivotable relative to the hand grip assembly receiving portion. The at least one releasable fastener is operative to selectively and releasably fix the elongated member relative to the elongated hollow member.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an adjustable handlebar for a vehicle. 
       BACKGROUND OF THE INVENTION 
       [0002]    Straddle-type vehicles, such as motorcycles, all-terrain vehicles (ATVs), personal watercraft, and three-wheeled road vehicles, are usually steered by a handlebar. Referring to  FIG. 1 , an exemplary prior art handlebar  10  is mounted to a vehicle (not shown) by clamping a clamp bar  14  portion of the handlebar  10  to a steering column  12  of the vehicle. The handlebar  10  is positioned forwardly of a straddle seat of the vehicle, and has left and right hand grips  16  on which the driver places his hands to steer the vehicle. The hand grips  16  are oriented generally transversely to the direction of travel of the vehicle, and may be angled rearwardly and either upwardly or downwardly to ensure that the hand grips  16  can be comfortably gripped by a typical driver, for example a 50 th  percentile adult male. The position of the hand grips  16  relative to the seat may be adjusted by pivoting the handlebar  10  about a horizontal clamp bar axis  18  coaxial with the clamp bar  14 , to accommodate riders of different heights or arm lengths, or in different riding positions. 
         [0003]    This type of handlebar has a number of drawbacks. While the position of the handlebar  10  is adjustable about the clamp bar axis  18 , adjusting the position in this manner varies the position of the hand grips  16  both vertically and forwardly/rearwardly at the same time. Therefore, it offers only one degree of freedom for drivers who may wish to adjust more than one parameter independently, and the lateral separation of the hand grips is not adjustable at all. In addition, pivoting the handlebar  10  about the clamp bar axis  18  changes the orientation of the hand grips  16 , which may result in poor ergonomics which are uncomfortable for the driver, particularly on longer trips. 
         [0004]    This drawback is exacerbated when vehicle controls for controlling an operation of the vehicle, such as a throttle actuator, a brake lever, and/or various switches and buttons, are provided on the handlebar. These controls are typically situated within reach of a driver so that the driver can conveniently reach and actuate them while maintaining a grip on the hand grips to control the vehicle. Pivoting the handlebar  10  about the clamp bar axis  16  may significantly change the orientation of the controls, making them inconvenient or even inoperable for some drivers at some angles. 
         [0005]    One attempt to address these problems is to provide additional degrees of freedom in adjusting the handlebar, such as an adjustable height riser supporting the handlebar on the steering column. However, an adjustable height riser does not completely address all of the drawbacks described above, and it is believed that further ergonomic improvements are possible. 
         [0006]    In addition, providing additional degrees of freedom is generally at odds with the need for a structurally rigid steering assembly to withstand the stresses that are exerted while using the vehicle, particularly in racing and other high-structural stress applications. In general, a single piece or solidly welded handlebar is preferred when maximum structural rigidity is desired. 
         [0007]    Therefore, there is a need for an adjustable steering assembly having more than one degree of freedom of adjustment. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to ameliorate at least some of the inconveniences present in the prior art. 
         [0009]    It is also an object of the present invention to provide a handlebar assembly having hand grips which are adjustable axially and radially. 
         [0010]    It is another object of the present invention to provide a vehicle having the above handlebar assembly. 
         [0011]    In one aspect, the invention provides a vehicle having a vehicle body, a straddle-type seat disposed on the vehicle body, and a steering device supported by the vehicle body and being disposed generally forwardly of the seat for steering the vehicle. The steering device has a left side and a right side. Each side has a hand grip assembly receiving portion having one of an elongated hollow member and an elongated member, a hand grip assembly and at least one releasable fastener. The hand grip assembly has the other of the elongated hollow member and the elongated member, and a hand grip disposed on the other of the elongated hollow member and the elongated member. The at least one releasable fastener is disposed on one of the elongated hollow member and the elongated member. The elongated member is received coaxially in the elongated hollow member. A common central longitudinal axis of the elongated member and the elongated hollow member is oriented generally horizontally when the vehicle is upright, stationary and steered straight. The hand grip is axially movable relative to the hand grip assembly receiving portion along the central longitudinal axis by moving the elongated member axially relative to the elongated hollow member along the central longitudinal axis between a plurality of axial positions. The hand grip is pivotable relative to the hand grip assembly receiving portion about the central longitudinal axis by pivoting the elongated member relative to the elongated hollow member about the central longitudinal axis between a plurality of orientations. The at least one releasable fastener is operative to selectively and releasably fix the elongated member relative to the elongated hollow member in any one of the plurality of axial positions and in any one of the plurality of orientations. 
         [0012]    In an additional aspect, the elongated hollow member is a generally cylindrical aperture, and the elongated member is a generally cylindrical member. 
         [0013]    In a further aspect, the at least one releasable fastener comprises at least one threaded fastener. Tightening the at least one threaded fastener urges at least a portion of the generally cylindrical aperture against the generally cylindrical member, thereby preventing both axial movement and pivotal movement of the generally cylindrical member relative to the generally cylindrical aperture. 
         [0014]    In an additional aspect, the plurality of axial positions is a plurality of predetermined axial positions, and the plurality of orientations is a plurality of predetermined orientations. 
         [0015]    In a further aspect, one of the generally cylindrical member and the generally cylindrical aperture further comprises at least one protrusion, and the other of the generally cylindrical member and the generally cylindrical aperture further comprises a plurality of recesses. Each recess of the plurality of recesses corresponds to one of the plurality of predetermined axial positions and one of the plurality of predetermined orientations of the generally cylindrical member relative to the generally cylindrical aperture, such that when the at least one protrusion is received in at least one recess of the plurality of depressions the generally cylindrical member is in the predetermined axial position and the predetermined orientation corresponding to the at least one recess. 
         [0016]    In an additional aspect, the at least one protrusion is movable relative to the one of the generally cylindrical member and the generally cylindrical aperture between a first position wherein the at least one protrusion is received in the at least one recess and a second position wherein the at least one protrusion is disengaged from the at least one recess. The at least one protrusion is biased toward the first position. 
         [0017]    In a further aspect, a release actuator operatively is connected to the at least one protrusion. The release actuator is operative to selectively move the at least one protrusion to the second position. 
         [0018]    In an additional aspect, a distal end portion of the generally cylindrical member has a diameter larger than the generally cylindrical aperture, thereby limiting an axial movement of the generally cylindrical member relative to the generally cylindrical aperture in a laterally outward direction. 
         [0019]    In a further aspect, the steering device is further pivotably connected to the vehicle body about a horizontal axis. The horizontal axis is disposed below the left and right hand grip assemblies when the vehicle is upright, stationary and steered straight. 
         [0020]    In an additional aspect, one of the generally cylindrical member and the generally cylindrical aperture has an annular channel formed therein. The annular channel has a first end and a second end defining a length of the channel therebetween. The other of the generally cylindrical member and the generally cylindrical aperture has a radial protrusion. The radial protrusion is received in the annular channel. The radial protrusion abuts against the first and second ends of the annular channel to define respective minimal and maximal orientations of the generally cylindrical member relative to the generally cylindrical aperture about the central longitudinal axis. 
         [0021]    In a further aspect, the length of the channel is selected such that an angular difference between the minimal and maximal orientations of the generally cylindrical member relative to the generally cylindrical aperture generally corresponds to a maximum angle of rotation of the steering device relative to the vehicle body about the horizontal axis. 
         [0022]    In an additional aspect, at least one hand grip assembly of the left and right hand grip assemblies comprises at least one controller disposed thereon. The at least one controller is operatively connected to the vehicle for controlling an operation of the vehicle. The at least one controller is axially movable and pivotable with the at least one hand grip relative to the hand grip assembly receiving portion. 
         [0023]    In another aspect, the invention provides an adjustable handlebar assembly having a left side and a right side. Each side has a hand grip assembly receiving portion having one of an elongated hollow member and an elongated member, a hand grip assembly and at least one releasable fastener. The hand grip assembly has the other of the elongated hollow member and the elongated member, and a hand grip disposed on the other of the elongated hollow member and the elongated member. The at least one releasable fastener is disposed on one of the elongated hollow member and the elongated member. The elongated member is received coaxially in the elongated hollow member. A common central longitudinal axis of the elongated member and the elongated hollow member is generally coaxial with an axis of the hand grip assembly. The hand grip is axially movable relative to the hand grip assembly receiving portion along the central longitudinal axis by moving the elongated member axially relative to the elongated hollow member along the central longitudinal axis between a plurality of axial positions. The hand grip is pivotable relative to the hand grip assembly receiving portion about the central longitudinal axis by pivoting the elongated member relative to the elongated hollow member about the central longitudinal axis between a plurality of orientations. The at least one releasable fastener is operative to selectively and releasably fix the elongated member relative to the elongated hollow member in any one of the plurality of axial positions and in any one of the plurality of orientations. 
         [0024]    In a further aspect, the elongated hollow member is a generally cylindrical aperture and the elongated member is a generally cylindrical member. 
         [0025]    In an additional aspect, the at least one releasable fastener comprises at least one threaded fastener. Tightening the at least one threaded fastener urges at least a portion of the generally cylindrical aperture against the generally cylindrical member, thereby preventing both axial movement and pivotal movement of the generally cylindrical member relative to the generally cylindrical aperture. 
         [0026]    In a further aspect, the plurality of axial positions is a plurality of predetermined axial positions, and the plurality of orientations is a plurality of predetermined orientations. 
         [0027]    In an additional aspect, one of the generally cylindrical member and the generally cylindrical aperture further comprises at least one protrusion, and the other of the generally cylindrical member and the generally cylindrical aperture further comprises a plurality of recesses. Each recess of the plurality of recesses corresponds to one of the plurality of predetermined axial positions and one of the plurality of predetermined orientations of the generally cylindrical member relative to the generally cylindrical aperture, such that when the at least one protrusion is received in at least one recess of the plurality of depressions the generally cylindrical member is in the predetermined axial position and the predetermined orientation corresponding to the at least one recess. 
         [0028]    In a further aspect, the at least one protrusion is movable relative to the one of the generally cylindrical member and the generally cylindrical aperture between a first position wherein the at least one protrusion is received in the at least one recess and a second position wherein the at least one protrusion is disengaged from the at least one recess. The at least one protrusion is biased toward the first position. 
         [0029]    In an additional aspect, a release actuator is operatively connected to the at least one protrusion. The release actuator is operative to selectively move the at least one protrusion to the second position. 
         [0030]    In a further aspect, a distal end portion of the generally cylindrical member has a diameter larger than the generally cylindrical aperture, thereby limiting an axial movement of the generally cylindrical member relative to the generally cylindrical aperture in a laterally outward direction. 
         [0031]    In an additional aspect, one of the generally cylindrical member and the generally cylindrical aperture has an annular channel formed therein. The annular channel has a first end and a second end defining a length of the channel therebetween. The other of the generally cylindrical member and the generally cylindrical aperture has a radial protrusion. The radial protrusion is received in the annular channel. The radial protrusion abuts against the first and second ends of the annular channel to define respective minimal and maximal orientations of the generally cylindrical member relative to the generally cylindrical aperture about the central longitudinal axis. 
         [0032]    In a further aspect, at least one hand grip assembly of the left and right hand grip assemblies comprises at least one controller disposed thereon. The at least one controller is operatively connectable to a vehicle for controlling an operation of the vehicle. The at least one controller is axially movable and pivotable with the at least one hand grip relative to the hand grip assembly receiving portion. 
         [0033]    For the purposes of this application, directional terms such as forward, rearward, left, and right, in reference to a vehicle or a part of a vehicle, are as they would be understood by a driver driving the vehicle in a normal driving position. 
         [0034]    For the purposes of this application, when relative movement or rotation between two objects is described, it should be understood that either of the two objects could be held stationary while the other undergoes the movement or rotation with respect to it. 
         [0035]    Embodiments of the present invention each have at least one of the above-mentioned objects and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present invention that have resulted from attempting to attain the above-mentioned objects may not satisfy these objects and/or may satisfy other objects not specifically recited herein. 
         [0036]    Additional and/or alternative features, aspects, and advantages of embodiments of the present invention will become apparent from the following description, the accompanying drawings, and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    For a better understanding of the present invention, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where: 
           [0038]      FIG. 1  is a rear elevation view of a prior art handlebar; 
           [0039]      FIG. 2  is a right side elevation view of a snowmobile; 
           [0040]      FIG. 3  is a right side elevation view of a personal watercraft; 
           [0041]      FIG. 4  is a right side elevation view of an ATV; 
           [0042]      FIG. 5  is a top plan view of a three-wheeled motorized vehicle; 
           [0043]      FIG. 6  is a rear, right perspective view of a steering assembly according to a first embodiment; 
           [0044]      FIG. 7  is a front elevation view of the steering assembly of  FIG. 6 , with a portion thereof shown as a cross-section; 
           [0045]      FIGS. 8A and 8B  are front elevation views of the steering assembly of  FIG. 6 , with the hand grip portions shown in different axial positions; 
           [0046]      FIGS. 9A-9C  are left side elevation views of the steering assembly of  FIG. 6 , with the hand grip portions shown in different angular orientations; 
           [0047]      FIG. 10A  is a cross-sectional view of a hub according to a second embodiment; 
           [0048]      FIG. 10B  is a partial side view of hand grip portion according to the second embodiment; and 
           [0049]      FIG. 11  is a front elevation view of a steering assembly according to a third embodiment, with a portion thereof shown as a cross-section. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0050]    A handlebar according to the present invention could be used on many types of vehicles. Some examples of vehicles on which such a handlebar could be used, namely a snowmobile, a personal watercraft, an ATV, and a three-wheeled motorized vehicle, will be described below. However it should be understood that such a handlebar could be used on other types of vehicles, such as a motorcycle for example. 
         [0051]      FIG. 2  shows a side elevation view of a snowmobile  110  having a forward end  112  and a rearward end  114 . The snowmobile  110  has two laterally spaced skis  116 , each mounted on the frame  118  via a suspension  120  in a known manner. The frame  118  includes a tunnel portion  122  and an engine compartment  124  forward of the tunnel portion  122 . The tunnel portion  122  generally includes one or more pieces of sheet metal bent into an inverted U-shape. The snowmobile  110  also has an engine  126  (shown schematically) carried by the engine compartment  124 . The engine  126 , via a transmission (not shown), powers a rear track  218  disposed within the tunnel portion  122  to propel the vehicle. The operation of the engine  126  is controlled by an electronic control unit (ECU) (not shown). The vehicle frame  118  supports a number of fairings  130  which provide aesthetic appeal and protect the rider from dirt and snow that may be lifted by the track  128  while the snowmobile  110  is in use. 
         [0052]    A straddle seat  132  mounted on the frame provides a seating position for a rider. The snowmobile  110  may alternatively have additional seating positions for one or two passengers. A pair of footrests  134  are provided below the seat  132  for the rider to rest his feet thereon. 
         [0053]    A handlebar  136  is provided generally forward of the seat  132 . The handlebar  136  has a left hand grip  138  and a right hand grip  140  that can be gripped by the rider. The hand grips  138 ,  140  are connected to a steering column  142 . The steering column  142  is connected to the front skis  116  in a known manner, such that turning the hand grips  138 ,  140  turns the skis  116  to steer the snowmobile  110 . A brake actuator, in the form of a hand brake lever  144 , is provided near the right hand grip  140  for braking the snowmobile  110  in a known manner. A display cluster  148  is provided forward of the seat  132 . 
         [0054]      FIG. 3  shows a side elevation view of a personal watercraft  200  having a vehicle body made of a hull  202  and a deck  204 . The hull  202  buoyantly supports the watercraft  200  in the water, and the deck  204  is designed to accommodate a rider and passengers. The volume created between the hull  202  and the deck  204  is known as the engine compartment. The engine compartment accommodates the engine  206  (shown schematically) as well as the exhaust system, gas tank, electrical system (battery, ECU . . . ), air box, storage bins (not shown) and other elements required or desired for the watercraft  200 . 
         [0055]    The deck  204  has mounted thereon a straddle seat  208  placed on top of a pedestal  210  to accommodate a rider in a straddling position. A grab handle  212  is provided between the pedestal  210  and the seat  208  at the rear of the seat  208  to be gripped by a passenger. 
         [0056]    A handlebar  214  is positioned generally forward of the seat  208 . The handlebar  214  has a hand grip assembly receiving portion  216 , that may be padded, and a pair of hand grips  218 . One of the hand grips  218  is provided with a throttle operator in the form of a thumb-actuated throttle lever  220 . Other types of throttle operators, such as a finger-actuated throttle lever and a twist grip, are also contemplated. A display cluster  224  is located forwardly of the handlebar  214  for displaying information to the rider. 
         [0057]    The watercraft  200  is propelled by a jet propulsion system  226  including a jet pump (not shown). It is contemplated that other types of propulsion system, such as propellers, could be used. The jet propulsion system  226  pressurizes water and accelerates it to create thrust. The water is first scooped from under the hull  202  through an inlet grate  228 . The inlet grate  228  prevents large rocks, weeds, and other debris from entering the jet propulsion system  226  since they may damage it or negatively affect its performance. Water then flows through the water intake ramp (not shown). From the intake ramp, water then enters the jet pump. The jet pump is made of two main parts: the impeller (not shown) and the stator (not shown). The impeller is coupled to the engine  206  by one or more shafts  230 , such as a driveshaft and an impeller shaft. The rotation of the impeller pressurizes the water, which then moves over the stator that is made of a plurality of fixed stator blades (not shown). The role of the stator blades is to decrease the rotational motion of the water so that almost all the energy given to the water is used for thrust, as opposed to swirling the water. Once the water leaves the jet pump, it goes through the venturi (not shown). Since the venturi&#39;s exit diameter is smaller than its entrance diameter, the water is accelerated further, thereby providing more thrust. A steering nozzle  232  is pivotally attached to the venturi through a vertical pivot point. The steering nozzle  232  is operatively connected to the handlebar  214  via a push-pull cable (not shown) such that when the handlebar  214  is turned, the steering nozzle  232  pivots, redirects the water coming from the venturi, so as to steer the watercraft  200  in the desired direction. 
         [0058]      FIG. 4  shows a side elevation view of an ATV  300  having two laterally spaced front wheels  302  and two laterally spaced rear wheels  304 , each mounted on the frame  306  via a suspension  308  in a known manner. Each of the front wheels  302  and the rear wheels  304  has mounted thereon a low-pressure balloon tire. The front wheels are each provided with a brake (not shown) for braking the ATV  300  in a known manner. The rear wheels  304  are powered by an engine  312  (shown schematically) via a transmission (not shown) to propel the ATV  300 . The operation of the engine  312  is controlled by an ECU (not shown). The frame  306  supports a number of fairings  316  which provide aesthetic appeal and protect the rider from dirt and water that may be lifted by the tires while the vehicle is in use. 
         [0059]    A straddle seat  318  mounted on the frame  306  provides a seating position for a rider. The ATV  300  may also have a second seating position for a passenger. A pair of footrests  320  is provided below the seat  318  for the rider to rest his feet thereon. 
         [0060]    A handlebar  322  is provided generally forward of the seat  318 . The handlebar  322  has a pair of hand grips  324  that can be gripped by a rider. The hand grips  324  are connected to a steering column  326 . The handlebar  322  is connected to the front wheels  302  in a known manner, such that turning the handlebar  322  turns the front wheels  302  to steer the ATV  300 . A display cluster  330  is provided forward of the seat  318 . 
         [0061]      FIG. 5  shows a top view of a three-wheeled motorized vehicle  400 . having two laterally spaced front wheels  402  and a single rear wheel  404 , each mounted on the frame (not shown) via a suspension  406  in a known manner. Each of the front wheels  402  and the rear wheel  404  has mounted thereon a tire  408  suitable for road use. It is contemplated that the rear wheel  404  may have two or more tires disposed next to each other mounted thereon and still be considered a single wheel. The front and rear wheels  402 ,  404  are each provided with a brake (not shown). The rear wheel  404  is powered by an engine  410  (shown schematically) via a transmission (not shown) to propel the vehicle  400 . The operation of the engine  410  is controlled by an ECU (not shown). The vehicle frame supports a number of fairings  412  which provide aesthetic appeal and protect the rider from dirt and water that may be lifted by the tires  408  while the vehicle is in use. 
         [0062]    A straddle seat  414  mounted on the frame provides a first seating position  416  for a rider, and a second seating position  418  for a passenger. The vehicle  400  may alternatively have only a single seating position  416  for the rider. A pair of grab handles  430  is provided to be gripped by the passenger. A pair of rider foot pegs  420  and a pair of passenger foot pegs  422  are provided below the seat  414  for the rider and passenger, respectively, to rest their feet thereon. 
         [0063]    A handlebar  423  is provided generally forward of the seat  414 . The handlebar  423  has a left hand grip  424  and a right hand grip  426  that can be gripped by a rider. The hand grips  424 ,  426  are connected to a steering column  428 . The handlebar  423  is connected to the front wheels  402  in a known manner, such that turning the hand grips  424 ,  426  turns the wheels  402  to steer the vehicle  400 . A brake actuator, in the form of a hand brake lever  432 , is provided near the left hand grip  424  for braking the vehicle  400 . A display cluster  436  is provided forward of the seat  414 , for displaying information to the rider. 
         [0064]    Referring now to  FIGS. 6-11 , various embodiments of handlebars will be described. It should be understood that the handlebars described below could be used as a handlebar (i.e. handlebar  136 ,  214 ,  322 , or  423 ) on any one of the vehicles described above. 
         [0065]    Referring to  FIGS. 6-9C , a handlebar  500 , according to a first embodiment, includes a hand grip assembly receiving portion  502  having a central hub  504  mounted to the vehicle via a base  506 . A releasable latch  508  allows the portion  502  to pivot with respect to the base  506  about a transverse axis  509 . In this embodiment, the hub  504  pivots to a number of predetermined orientations in which the latch  508  is received in one of the recesses  510 , allowing a maximum of 36° of rotation. Left and right hand grip assemblies  512 , each having a hand grip  514 , are received in the hub  504  in a manner that will be described below in further detail. In this embodiment, a housing  516  mounted on each hand grip assembly  514  has controllers including a lever  518  and buttons  520  for controlling aspects of the operation of the vehicle. The aspects of the vehicle controlled by the lever  518  and buttons  520  depend on the particular vehicle, but may include throttle, braking, reverse gear actuation, gear shifting, the display cluster, and starting and stopping the vehicle. The controllers are positioned relative to the hand grips  514  so that the driver of the vehicle can conveniently operate the controllers with his thumb or other fingers without removing his hands from the hand grips  514 . It is contemplated that more or fewer controllers, or controllers of different, types may be provided. It is further contemplated that the controllers may alternatively control different operations. It is further contemplated that the controllers or parts thereof may be omitted, in which case the necessary controllers for operating the vehicle would be provided elsewhere on the vehicle, for example in the form of pedals within reach of the driver&#39;s feet. Each hand grip  514  has a central longitudinal axis  522  ( FIG. 7 ) that is generally horizontal when the vehicle is upright and steered straight. 
         [0066]    Referring now to  FIG. 7 , the left hand grip assembly  512  will be described. It should be understood that the right hand grip assembly  512  is substantially a mirror image thereof and operates in a similar manner. As such, the right hand grip assembly  512  will not be separately described. 
         [0067]    The hand grip  514  is attached at a medial end thereof to an elongated member in the form of a generally cylindrical member  524  having a central longitudinal axis  526  oriented generally horizontally and co-axially with the axis  522  of the hand grip  514 . It is contemplated that the axes  522 ,  526  may alternatively not be coaxial. The generally cylindrical member  524  is received in an elongated hollow member in the form of a generally cylindrical aperture  528  of the hub  504 . The aperture  528  is of sufficient length to provide the necessary rigidity to the hand grip assembly  512 . It is contemplated that the elongated member and the elongated hollow member could have shapes other than cylindrical. For example, it is contemplated that the elongated member could have an hexadecagonal cross-section, while the elongated hollow member could have an octagonal aperture. 
         [0068]    Two threaded fasteners in the form of hex head bolts  530  can be tightened to constrict the size of the aperture  528  and urge the walls of the aperture  528  against the generally cylindrical member  524  to maintain the generally cylindrical member  524  fixed in position relative to the hub  504 . It is contemplated that other types of releasable fasteners could be used such as, for example, screws, knobs having a threaded stud, latches, quarter turn fasteners, or other types of threaded or quick release fasteners. The bolts can be loosened to release the generally cylindrical member  524  to permit adjustments of the hand grip assembly  512  relative to the hub  504  as will be described below in further detail. The hub  504  is preferably made of aluminum or stainless steel to provide structural rigidity, but it could be made of other materials such as polymers or composite materials. The hand grip assembly  512  preferably has an aluminum, stainless steel, or steel interior  532  and a plastic layer  534  overmolded thereon. The plastic layer  534  protects the interior  532  of the generally cylindrical member  524  from scratches or abrasions due to the repeated constricting of the aperture  528  that may result in oxidation of the metal. A portion of the housing  516  may be overmolded concurrently with the plastic layer  534 . It is contemplated that other suitable materials may alternatively be used. 
         [0069]    When the driver wishes to make adjustments to the hand grips  514 , he first loosens the bolts  530  using a hex key (not shown) or other suitable tool. It is contemplated that any other suitable method of loosening the bolts  530  may be provided. The driver can then slide the generally cylindrical member  524  inwardly or outwardly along the axis  526  relative to the hub  504  to adjust the lateral separation of the left and right hand grips  514 . An end portion  536  of the generally cylindrical member has a cap  538  of larger diameter than the generally cylindrical aperture  528 . The range of motion along the axis  526  is limited when the housing  516  or the cap  538  abuts against the generally cylindrical aperture  528  or another portion of the hub  504 . In one embodiment, the full range of motion of each hand grip  514  is about one inch ( 2 . 54  cm), permitting the lateral separation of the hand grips  514  to be adjusted by as much as two inches ( 5 . 08  cm). Two exemplary lateral separations of the hand grips  514  are shown in  FIGS. 8A and 8B . The cap  538  additionally prevents the removal of the generally cylindrical member  524  from the generally cylindrical aperture  528 . When the bolts  530  are loosened, the generally cylindrical member  524  can also be pivoted about the axis  526  relative to the hub  504  to adjust the orientation of the hand grips  514 . Three exemplary orientations of the hand grips  514  are shown in  FIGS. 9A ,  9 B and  9 C. When the hand grips  514  are in the position and orientation desired by the driver, the driver tightens the bolts  530  and the hand grips  514  are maintained in a constant position and orientation relative to the hub  504 . 
         [0070]    Referring to  FIGS. 10A and 10B , a handlebar  600  according to a second embodiment will be described. Features of the handlebar  600  that are similar to features of the handlebar  500  of  FIG. 6-9C  have been given similar numbers with different first digits, or are not shown in this embodiment, and will not be described again in detail. 
         [0071]    In this embodiment, the generally cylindrical aperture  628  has an annular channel  640  for receiving a radial protrusion  642  disposed on the generally cylindrical member  624 . It is contemplated that the generally cylindrical member  624  may alternatively have the annular channel  640 , in which case the generally cylindrical aperture would have the radial protrusion  642 . When the hand grip assembly  612  is pivoted about the axis  626 , the protrusion  642  abuts against the sides  644 ,  646  of the channel  640  to define minimum and maximum orientations of the hand grip assembly  612  relative to the hub  604 . The channel  640  may be dimensioned to have an arc length of 36° between the sides  644 ,  646  such that the available range of orientations generally corresponds to the angle through which the hub  604  may pivot about the transverse axis  609 , such that the hand grips  614  may be maintained in an approximately constant orientation irrespective of the orientation of the hub  604  relative to the body of the vehicle. When the hand grip assembly  612  is moved axially along the axis  626 , the protrusion  642  abuts against the sides  648 ,  650  of the channel  640  to define minimum and maximum lateral positions of the hand grip assembly  612  relative to the hub  604 . In this manner, the channel  640  and the protrusion  642  perform a function similar to that of the cap  538  of the embodiment of  FIGS. 6-9C . 
         [0072]    An array of recesses  652  is formed in the generally cylindrical aperture  628  for receiving a protrusion  654  on the generally cylindrical member  624 . As the driver changes the axial position or orientation of the hand grip assembly  612 , the protrusion  654  is received in different ones of the recesses  652 . Each of the recesses  652  corresponds to a predetermined discrete position and orientation of the hand grip assembly  612 . When the driver adjusts the hand grip assembly  612  to any one of the predetermined positions and orientations, the protrusion  654  is received in the corresponding recess  652 . This assists the driver in reliably adjusting the hand grip assemblies  612  to a particular position and orientation, and in adjusting the left and right hand grip assemblies  612  to the same position and orientation to obtain a symmetric arrangement. The driver may then fix both hand grip assemblies  612  in position by tightening the bolts  630 . In this embodiment, the protrusion  654  is mounted on a resilient strip of material  656  inside the generally cylindrical portion  624 . When the driver adjusts the hand grip assembly  612 , the protrusion  654  is displaced radially inwardly against the biasing force of the strip of material  656  until the protrusion  654  aligns with another one of the recesses  652 . It is contemplated that the protrusion  654  may alternatively be made of a resilient material such that the protrusion deforms when it is not aligned with a recess  652 . It is further contemplated that the recesses  652  may alternatively be formed in the generally cylindrical member  624 , in which case the protrusion  654  would be formed in the generally cylindrical aperture  628 . It is also contemplated one of the generally cylindrical member  624  and the generally cylindrical aperture  628  could be provided with an array of protrusions while the other one of the generally cylindrical member  624  and the generally cylindrical aperture  628  would be provided with a recess. 
         [0073]    Referring to  FIG. 11 , a handlebar  700  will be described according to a third embodiment. Features of the handlebar  700  that are similar to features of the handlebar  500  of  FIGS. 6-9C  or the handlebar  600  of  FIGS. 10A and 10B  have been given similar numbers with different first digits, or are not shown in this embodiment, and will not be described again in detail. 
         [0074]    In this embodiment, the hand grip assembly  712  comprises a hand grip  714 , a housing  716 , and a generally cylindrical aperture  728 . The hub  704  has a generally cylindrical member  724  with a cap  738  at an end portion  736  thereof. The hand grip assembly  712  is movable relative to the hub  704  between a plurality of predetermined positions and orientations in which the protrusion  754  in the generally cylindrical aperture  728  aligns with one of the plurality of depressions  752  (only one of which is shown) in the generally cylindrical member  724 . A release actuator in the form of a button  758  is provided for selectively disengaging the protrusion  754  from the depression  752  to allow adjustment of the hand grip assembly  712 . It is contemplated that the release actuator  754  could be constructed so as to render the need of other releasable fasteners (such as the bolts  530  described above) unnecessary. 
         [0075]    Modifications and improvements to the above-described embodiments of the present invention may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.