Patent Publication Number: US-2010109267-A1

Title: Ski bike

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/110,023, filed Oct. 31, 2008, the entirety of which is herein incorporated by reference. 
    
    
     FIELD 
     The present disclosure relates to a gravity propelled, ski-supported vehicle. In particular, the present disclosure relates to such a vehicle that is adapted for use on snow. 
     BACKGROUND 
     Ski biking is a sport that has existed for over one hundred and fifty years. Essentially, ski biking involves a rider mounting a vehicle, a ski bike, that typically has a frame; a steering mechanism and a seat, each of which is coupled to the frame; and front and rear skis, coupled to the frame, for riding over a snow covered slope. The rider is able to sit on the ski bike and enjoyably coast down the slope. 
     Ski bikes presently known in the art suffer from several problems, however. For example, due to their bulkiness, it can be difficult to transport ski bikes on chair lifts. While U.S. Pat. No. 6,783,134 to Geary discloses a ski bike that is adapted to be carried on a ski lift with a rider, Geary teaches a ski bike having a pivotable seat that is adjustable to a lowered position, the rider able to mount the ski lift with the ski bike when the seat is in the lowered position. Drawbacks of the design in Geary, however, include that a relatively complex mechanical configuration is required to implement the pivotable seat, and that the rider may find it cumbersome to consistently have to raise and lower the pivotable seat when boarding and disembarking from ski lifts. 
       FIG. 1  (PRIOR ART) depicts another exemplary ski bike  100  known in the art. The ski bike  100  has a seat  160  that is coupled to a frame  110  via shock absorbers  180  that extend from the underside of the seat  160 . The ski bike  100  has not been adapted in any particular way to facilitate its transportation using, for example, a ski lift. 
     Consequently, there exists a need for a ski bike that improves on ski bikes known in the art. 
     SUMMARY 
     According to one embodiment, there is provided a ski vehicle for traveling along a surface. The ski vehicle includes a frame having a seat supporting member; a steering column rotatably coupled to the frame; a front ski, coupled to the steering column; a rear ski, coupled to the frame, the front and rear skis for supporting the ski vehicle on the surface; and a seat, coupled to the seat supporting member of the frame, for supporting a rider, the seat supporting member of the frame having sufficient length to allow a ski lift chair to slide thereunder; wherein the ski vehicle has a minimum design rider weight, and the weight distribution of the vehicle is selected so that the vehicle is secured on the ski lift chair when the seat is slid over the chair and a rider of at least the design rider weight is sitting on the seat. 
     The ski vehicle can further include a frame support member coupled between the seat supporting member and a location on the frame nearer to the front of and bottom of the ski vehicle, the frame support member angled such that when the chair of the ski lift slides under the frame support member and the rider sits on the seat, the front ski is angled upwards relative to the horizontal. 
     According to another embodiment, there is provided a ski vehicle for travelling along a surface. The ski vehicle includes a frame; a steering column rotatably coupled to the frame; a front ski, coupled to the steering column; a seat, coupled to the frame, for supporting a rider; a rear swing-arm having first, second and third corners, the first corner movably coupled to the frame and the second corner pivotably coupled to a pivot point on the frame such that the swing-arm pivots about the pivot point when the first corner is moved; and a rear ski, coupled to the rear swing-arm, for supporting the ski vehicle on the surface. 
     The rear ski of the ski vehicle may be coupled to the third corner of the rear swing-arm. The rear swing-arm may be triangular. The first corner of the rear swing-arm may be coupled to a location on the frame between the pivot point and the steering column. The ski vehicle may also include a shock absorber coupled between the frame and the first corner of the rear swing-arm. The shock absorber may be slidably coupled to the frame. If slidably coupled to the frame, the shock absorber may be coupled to the frame using a multi-position bracket slidable along the frame, the multi-position bracket secured to the frame using a retractable pin that is insertable through both the multi-position bracket and a hole in the frame, thereby securing the shock absorber to the frame. The hole in the frame be one hole in a series of holes in the frame, the multi-position bracket slidable along the frame such that the retractable pin can be inserted through any hole in the series of holes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of an exemplary ski bike of the prior art (PRIOR ART); 
         FIGS. 2 and 3  are perspective views of a ski bike according to a first embodiment; 
         FIG. 4  is a perspective view of a rider boarding a ski lift while sitting on the ski bike according to the first embodiment; 
         FIG. 5  is a detailed view of a release pin that aids in coupling a steering column of the ski bike to a frame of the ski bike, according to the first embodiment; 
         FIG. 6  is a detailed view of a multi-position bracket used to couple a shock absorber to the frame of the ski bike, according to the first embodiment; 
         FIG. 7  is a detailed view of a shock absorber located on the steering column of the ski bike, according to the first embodiment; 
         FIG. 8  is a detailed view of a rear ski mounting bracket that aids in coupling a rear ski to a rear swing-arm of the ski bike, according to the first embodiment; 
         FIG. 9  is a perspective view of an alternative steering column and front ski that can be coupled to the frame of the ski bike of the first embodiment; 
         FIG. 10  is a perspective view of a ski bike, incorporating the steering column depicted in  FIG. 9 , according to a second embodiment; and 
         FIG. 11  is a perspective view of a ski bike according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT 
     Directional terms such as “top”, “bottom”, “front”, “back”, “vertical” and “horizontal” are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any apparatus or components thereof are to be positioned during use or mounted in an assembly. 
     While the sport of ski biking has existed for over a hundred years, certain drawbacks in the designs of existing ski bikes have hindered the popularity of the sport. One problem with the design of existing ski bikes is that they are bulky, and consequently a rider can have difficulty transporting them up a ski hill. Because of their bulkiness, it can be very difficult and unsafe for a rider to board a ski lift with a ski bike. A rider who has to carry a ski bike in his or her lap, for example, may be unable to properly sit on a chair of the ski lift with the ski bike, and may be unable to close the safety bar of the ski lift. Many ski resorts have therefore prohibited the use of ski lifts to transport conventional ski bikes, which has severely hampered the growth of ski biking. 
     The ski bike described below addresses these issues in that it allows the rider to safely and easily board a ski lift with the ski bike. 
     Referring now to  FIGS. 2 and 3 , there are depicted perspective views of a ski bike  10  according to a first embodiment. The ski bike  10  has a frame  12 , which includes a parallelogram composed of a generally vertically extending front frame member, a pair of conjoined generally vertically extending rear frame members, and generally horizontally extending top and bottom frame members. A steering column  14  is rotatably coupled to the vertically extending front member of the frame  12 . Handle bars  22  extend from either side of the top of the steering column  14  so as to allow the rider to steer the ski bike  10 . A front suspension member  26  is at the bottom of the steering column  14  and is pivotably coupled thereto. The triangular front suspension member  26  depicted in  FIGS. 2 and 3  is discussed in more detail with respect to  FIG. 7 , below. At the bottom of the front suspension member  26  is a front ski  18 , which is coupled to the front suspension member  26  via a front ski bracket  20 . The front ski bracket  20  is fixed to the front ski  18 . Interposed between the front suspension member  26  and the front ski  18  is front elastomeric block  16  that acts to absorb forces subjected on the ski bike  10  during riding. A bolt, threaded through both the front ski bracket  20  and the front suspension member  26  can be used to secure the front ski  18  to the front suspension member  26 . The bolt can be a grade  6  or harder bolt. 
     The frame  12  includes a seat supporting member  48  on which is supported a seat  50  for supporting the rider. Located within the front of the seat  50  is a zippered storage compartment  51  that can be used to store the rider&#39;s belongings. Also coupled to the frame  12  is a triangular rear swing-arm  45 . The rear swing-arm  45  has three corners: first, second and third corners  61 ,  62  and  63 , respectively. The second corner  62  is pivotably coupled to the frame  12  via a pivot point  46 , which in this embodiment is a hardened bolt extending through a bracket extending upwardly from the bottom of the rear frame members. In the depicted embodiments, the bolt is journalled through the swing-arm  45 . The rear swing-arm  45  can be constructed using hollow tubing formed from mild steel or aluminum, for example. The first corner  61  is movably coupled to the frame  12  via a central shock absorber  40 . The central shock absorber  40  has a back end coupled to the rear swing-arm  45  and a front end coupled to the horizontally extending bottom frame member via an adjustable central bracket  42  that is slidably mounted to the bottom frame member. The central bracket  42  can be positioned at various locations along the frame  12  forward of (i.e.: nearer to the steering column  14 ) the pivot point  46 . The manner in which the central bracket  42  is adjustable is discussed in more detail with respect to  FIG. 6 , below. Coupled to the third corner  63  via a rear ski bracket  54  is a rear ski  52 , as discussed in greater detail with respect to  FIG. 8 , below. 
     Beneficially, the rider is able to adjust the height of the seat  50  by moving the central bracket  42  either towards the front (i.e.: towards the steering column  14 ) or the rear (i.e.: towards the seat  50 ) of the frame  12 . As the central bracket  42  is moved nearer to the front of the frame  12 , the rear swing-arm  45  pivots towards the frame  12  and the rear ski  52  is drawn towards the seat  50 , thereby effectively lowering the height of the seat  50 , which is beneficial for relatively short riders. In contrast, as the central bracket  42  is moved nearer to the rear of the frame  12 , the rear swing-arm  45  pivots away from the frame  12  and the rear ski  52  is pushed away from the seat  50 , thereby effectively raising the height of the seat  50 , which is beneficial for relatively tall riders. 
     Together, the front suspension member  26 , the rear swing-arm  45  and the central shock absorber  40  form part of the suspension system of the ski bike  10 . When the swing-arm  45  rotates, force is translated radially about the pivot point  46 . As the central bracket  42  is moved nearer to the front of the frame  12  and the seat  50  is lowered, a relatively high proportion of this radial force is transferred axially (as opposed to in shear) to the shock absorber  40 , and the shock absorber  40  is able to absorb this axially transmitted force. In contrast, when the central bracket  42  is moved towards the rear of the frame  12  and the seat is raised, a relatively high proportion of this radial force is transferred in shear (as opposed to axially) to the shock absorber  40 , and the shock absorber  40  is not able to absorb such force. Consequently, the suspension system of the ski bike  10  is relatively stiffer when the central bracket  42  is positioned near the rear of the frame  12  as opposed to when it is placed near the front of the frame  12 . 
     Referring now to  FIG. 6 , there is depicted a detailed view of the interface between the central bracket  42  and the frame  12 . Drilled into the frame  12  is a series of spaced holes  43 . The central bracket  42  envelops the frame  12  and is slidable relative to it. On one side of the central bracket  42  the shock absorber  40  is securely fastened to the central bracket  42 , and on an opposing side of the central bracket  42  is drilled a hole (not shown) through which a retractable pin (not shown) can be inserted. When the hole in the central bracket  42  is aligned with one of the holes  43  on the frame, and when the retractable pin is inserted through the aligned holes, the central bracket  42  is fixed relative to the frame  42 . Attached to one end of the retractable pin is a rotatable knob  44 . The retractable pin is threaded and can be screwed into and out of the frame  42  using the rotatable knob  44 . The interior of the central bracket  42  is threaded such that it can mate with and securely retain the retractable pin. While this exemplary embodiment relies on threaded coupling to secure the retractable pin within the frame  12 , in alternative embodiments (not depicted), the retractable pin may be coupled to a spring that, in its quiescent position, is able to push the retractable pin into and retain the retractable pin within the frame  12 . In this alternative embodiment, the rider would be able to move the central bracket  42  by pulling the rotatable knob  44  away from the frame  12 , which would bias the spring and retract the retractable pin from within the frame  12 , thereby allowing the central bracket  42  to be slid along the frame  12 . 
     Referring now to  FIG. 7 , there is depicted a detailed view of the front suspension member  26  that is utilized in the embodiment of the ski bike  10  illustrated in  FIGS. 2 and 3 . The front suspension member  26  is triangular and is formed from an elastomeric material, such as medium durometer petroleum rubber. The front suspension member  26  could also be formed using a material such as molded polyurethane having a durometer hardness of between  80  and  100 . An elastomeric block  28  forms part of the front suspension member  26 . When forces are transferred from the front ski  18  up through to the front suspension member  26 , the elastomeric block  28  is compressed, thereby absorbing some of the forces and dampening the forces felt by the rider. Bolted to the elastomeric block  28  is a front hand screw bracket  33  through which a front hand screw  32  is threaded. By rotating the front hand screw  32 , the front hand screw  32  can be positioned such that it impacts and compresses the elastomeric block  28 , which accordingly reduces the ability of the elastomeric block  28  to absorb and dampen forces exerted on the front ski  18 . The front hand screw  32  thereby effectively allows the rider to adjust the stiffness of the front suspension member  26 . 
     Referring now to  FIG. 8 , there is depicted a detailed view of the rear ski  52  and the rear ski bracket  54 . The rear ski bracket  54  is fixedly coupled to the rear ski  52  and is coupled to the rear swing-arm  45  via a bolt  53  that is threaded through one of three bolt holes  55  in the bracket  54  and through a hole in the rear swing-arm  45 . The position of the rear ski bracket  54  and rear ski  52  relative to the swing-arm  45  varies depending on which of the three bolt holes  55  is used. Interposed between the swing-arm  45  and the rear ski bracket  54  is an elastomeric block  56 . As with the front elastomeric block  16 , the rear elastomeric block  56  acts to absorb forces subjected on the ski bike  10  during riding. A rear hand screw  58  can be screwed, in a direction generally perpendicular to the ground, which can compress the elastomeric block  56 . Doing so reduces the ability of the elastomeric block  56  to absorb forces exerted on the rear ski  52 , thereby resulting in a stiffer, or bumpier, ride for the rider. An aluminum plate (not shown) beneath the rear elastomeric block  56  distributes the force exerted by the hand screw  58  along the length of the block  56 . 
     Referring now to  FIG. 5 , there is depicted a detailed view of a release pin  34  and release pin bracket  35  that can be used to attach and remove the steering column  14  to the frame  12 . The release pin  34  and release pin bracket  35  are also visible in  FIG. 9 , which is a perspective view of an alternative steering column  62 , especially designed for racing, that can be coupled to the frame  12  of the ski bike  10 . The release pin  34  is threaded through the pin bracket  35  and has on one end of it a handle  39  that can be grasped by the rider. The release pin  34  also has surrounding it a spring  38  that biases the release pin  34  against the bracket  35  such that, by default, the end of the pin  34  without the handle  39  protrudes through and out of the pin bracket  35 . The spring  38  is biased between an annular ring  41  welded to the pin  34  and the bracket. 
     Also visible in  FIG. 9  on the alternative steering column  62  is a peg  36  (present on, but not illustrated in the figures that depict the steering column  14 ), collinear with the release pin  34 . The peg  36 , in conjunction with the release pin  34 , assists in keeping the steering columns  14 ,  62  attached to the frame  12 . Assuming the rider wants to attach one of the steering columns  14 ,  62  on to the ski bike  10 , the rider can grasp and pull the handle  39  to retract the release pin  34  such that the end of the pin  34  without the handle  39  no longer protrudes from the pin bracket  35 ; align the peg  36  with and insert the peg  36  into a bottom portion  66  of the frame  12  that is adapted to receive the peg  36 ; while continuing to grasp the handle  39 , align the release pin  34  with a top portion  68  of the frame  12  that is adapted to receive the release pin  34 ; and release the handle  39 , thereby allowing the spring  38  to push the release pin  34  into the top portion of the frame  12 . Optionally, inserted within the top and bottom portions of the frame  12  are reinforcing sleeve inserts  37  made of plastic or nylon, for example. 
     Similarly, to remove one of the steering columns  14 ,  62  from the frame  12 , the rider can simply grasp and pull the handle  39  such that the release pin  34  is retracted into the pin bracket  35  and then remove the steering column  14 ,  62  from the frame  12 . 
     Notably, when one of the steering columns  14 ,  62  is securely coupled to the frame  12 , only the pin bracket  35 , the peg  36  and the portion of the steering column  14 ,  62  immediately surrounding the peg  36  contact the frame  12 . 
     Consequently, any forces transmitted to the steering column  14 ,  62  will not bias the spring  38 , and there is no risk that the steering column  14 ,  62  will be decoupled from the frame  12  while riding the ski bike  10 . 
     Referring now to  FIG. 10 , there is depicted a ski bike  10  utilizing the alternative steering column  62 , according to a second embodiment. In lieu of a front suspension member  26  that uses the elastomeric block  28  as depicted in the first embodiment, the front suspension member  26  of this second embodiment utilizes a coil spring shock absorber  30  that is bolted to opposing suspension brackets  24 . The coil spring shock absorber  30  is especially useful when the ski bike  10  is used in racing. 
     Additionally, when the ski bike  10  is being transported in, for example, a car or gondola, the steering column  14 ,  62  can be removed from the ski bike  10  so that the amount of space required to transport the ski bike  10  is reduced, thereby making ski bike  10  transportation easier. 
     Referring now to  FIGS. 2 ,  3  and  10 , the manner in which the ski bike  10  is adapted to allow it to be easily transported using a ski lift is illustrated. The seat  50  of the ski bike  10  is mounted on a seat supporting member  48 , which forms part of the frame  12 . Compared to conventional ski bikes  10 , the seat supporting member  48  has been extended and angled such that it is at least long enough and properly positioned to easily allow a chair of a typical ski lift to slide thereunder. When the ski lift chair is under the seat supporting member  48 , the rider may sit down on the seat  50 , thereby securing the ski bike  10  to the ski lift chair using his or her own body weight. The ski lift can then transport both the rider and the ski bike  10  up a ski hill. As the ski bike  10  does not have to be awkwardly carried by the rider while seated in the ski lift chair, a ski lift safety bar may be safely closed over the rider even when the rider has boarded the ski lift with the ski bike  10 . When the rider wishes to disembark from the ski lift, he or she may simply push off from the chair of the ski lift using the ground, thereby sliding the seat  50  off of the chair. 
     The ski bike  10  depicted in the figures also includes first and second strut pairs  64  and  65 , respectively. The first strut pair  64  is coupled on one end to the seat supporting member  48  and on the other end to each of the vertically extending rear frame members. The first strut pair  64  transfers load borne by the seat supporting member  48  into the bulk of the frame  12 , thereby aiding in the structural stability of the ski bike  10 . When the rider sits on the seat  50  and when the chair of the ski lift is under the seat supporting member  48  and the first strut pair  64 , parts of the first strut pair  64  will be pressed against the chair. This will angle the front ski  18  of the ski bike  10  upwards relative to the horizontal; i.e., relative to the position of the front ski  18  when the front ski  18  is resting on the ground prior to the rider boarding the ski lift. This advantageously provides some clearance between the ground and the front ski  18  when the ski bike  10  is being carried up the ski hill, and decreases the likelihood that the front ski  18  will impact or get caught on the ground or on any obstructions on the ground. The upwards angling provided by the first strut pair  64  is especially useful at the top of a ski hill when the rider is disembarking from the ski lift, as without the first strut pair  64  the front ski  18  would be prone to pointing and digging into the ground during disembarking, thus preventing smooth ski lift operations. Typically, angling the first strut pair  64  such that it makes an angle of about 10 or 20 degrees relative to the horizontal results in sufficient upwards angling of the front ski  18 . 
     The second strut pair  65  is coupled on one end to the pair of vertically extending rear frame members and on another end to the horizontally extending bottom frame member. As with the first strut  64 , the second strut  65  helps to distribute forces borne by the ski bike  10  throughout the frame  12 , thereby aiding in the structural stability of the ski bike  10 . 
     Typically, the seat  50  is no more than 4 inches high so as to ensure that the rider is not elevated too far off the ski lift chair. The length of the portion of the seat supporting member  48  is the depth of a typical ski lift chair, typically between 16 and 18 inches. This allows the entirety of the ski lift chair to fit under the seat  50 , while still placing the rider within comfortable reach of the handle bars  22 . A seat that is too long would allow the rider to sit such that the rider&#39;s center of gravity is too far behind the center of the rear ski  52 , which could result in ski bike  10  instability. 
     The maximum weight of the ski bike  10  is typically about 12 kg, less than half of which is distributed near the front of the ski bike  10 . Typically, one third of the ski bike weight is supported by the front ski  18  and two thirds of the ski bike weight is supported by the rear ski  52 . The rider weight is positioned over the centre of the rear ski  52 . This allows for a wide range of rider weight to be accommodated on the ski bike. For a ski bike  10  of about 12 kg, a rider weight of at least 50 kg is more than sufficient to secure the ski bike  10  to the ski lift chair. Specifically, the ski bike  10  has a minimum design rider weight, and when the weight of the rider is at least this minimum design rider weight, the weight of the rider prevents the ski bike  10  from pivoting about the edge of the ski lift chair and throwing the rider off of the chair. The weight of the rider results in torque being applied to the ski bike  10 , which acts to secure the ski bike  10  to the ski lift chair. This torque is greater than and opposes the torque that results from the weight of the ski bike  10  that is distributed forward of the edge of the ski lift chair. It is in this fashion that the weight distribution of the vehicle is selected so that the vehicle is secured on the ski lift chair when the seat is slid over the chair and a rider of at least the design rider weight is sitting on the seat. The ski bike  10  can be manufactured in different weights, in which case the minimum design rider weight can be adjusted accordingly. If necessary, lead ballast can be added to the ski bike  10  to increase the ski bike weight to international racing standards of 20 kg. 
     Referring now to  FIG. 4 , riders are depicted boarding a ski lift with the ski bike  10 . As described above, the rider is able to be transported using the ski lift by allowing the chair of the ski lift to slide under the seat  50  of the ski bike  10  and by then simply sitting down. Also as described above, there is sufficient clearance between the front ski  18  and the ground to avoid having the front ski  18  contact the ground or any obstacles thereon. The ski bike  10  can be easily transported up the ski hill in a simple and safe fashion. Ample space exists for a safety bar to secure the riders in place. 
     One advantage of the present ski bike  10  is that in order to implement the suspension system of the ski bike  10 , the ski bike  10  utilizes a combination of the rear swing-arm  45  coupled to the central shock absorber  40 , which is coupled to the frame  12  at a location forward of the pivot point  46 . In contrast to conventional ski bike designs, the design of the current ski bike  10  does not require a shock absorber to be placed directly under the seat  50 . By utilizing the central shock absorber  40 , which is located forward of the seat  50 , space is created for the chair of a ski lift to slide under the seat  50 , thereby facilitating easy transport of the ski bike  10  on the ski lift. 
     Alternative Embodiment 
     Referring now to  FIG. 11 , there is depicted an alternative embodiment in which the pair of conjoined generally vertically extending rear frame members is replaced with a single generally vertically extending rear frame member  70 . Additionally, the first and second strut pairs  64 ,  65  are replaced with first, second and third single struts  72 ,  74 ,  76 , respectively. The struts  72 ,  74 ,  76  are joined together at a common connection point  77 . Third strut  76  extends from the connection point  77  and is joined to the underside of the seat supporting member  48 , while first and second struts  72 ,  74  extend from the connection point  77  and are joined to the top and bottom of the generally vertically extending rear frame member  70 . Furthermore, instead of being formed from a single triangular member, the rear swing-arm  45  is formed from a pair of conjoined triangular members  78 ,  80  that are joined together, with each triangular member placed on either side of the frame  12 . Instead of having the swing-arm  45  sandwiched by the frame  12 , as described with respect to the first and second embodiments above, in this alternative embodiment the the frame  12  is sandwiched by the swing-arm  45 . 
     While illustrative embodiments of the invention have been described, it will be appreciated that various changes can be made therein without departing from the scope and spirit of the invention, as defined in the claims.