PATENT ABSTRACT
A retention system for retaining a climbing skin to the tail end of a ski comprises an elongated resilient tensioning member secured to one end of the skin, a generally C-shaped clip adapted to removably hook about the tail end, and means on an upper portion of said clip for releasably retaining a portion of said tensioning member thereon. In the preferred embodiment the upper portion of the clip includes an aperture for receiving the tensioning member therethrough and a projection for engaging in one of several eyelets provided on the tensioning member.

PATENT DESCRIPTION
FIELD OF THE INVENTION 
     This invention relates to a system for securing a climbing skin to the bottom of a ski. In particular, the invention relates to a system for securing a climbing skin to one end of the ski, particularly the tail end of the ski, for tensioning a climbing skin. 
     BACKGROUND OF THE INVENTION 
     Climbing skins have been used on skis for many, many years to assist skiers in ascending slopes. Original climbing skins were made from the skins of animals. More recently, climbing skins have been made from synthetic fabrics which have a nap of stiff, rearwardly angled fibers projecting from their bottom surfaces. When the skins are attached to the skis, the skis can be slid in a forward direction relatively easily. When the skis are moved in a rearward direction then the fibers bite into the snow. By attaching climbing skins to both skis, a skier can up even a reasonably steep snow slope by sliding one ski forward and then the other. 
     Attaching a climbing skin securely to the bottom of a ski in such a way that the climbing skin will not be easily dislodged during use and snow will not build up between the base of the ski and the climbing skin can be difficult. The problem of securely attaching climbing skins to skis is exacerbated by the fact that a skier my repeatedly put climbing skins onto skis and take them off during the course of a days skiing. 
     Early climbing skins simply had straps which were used to attach the climbing skin to the ski. Typically straps were provided to stretch the climbing skin between the tip and tail of the ski and additional straps were provided along the edges of the climbing skin. The additional straps could be used to tie the climbing skin to the ski itself. Such climbing skins tended not to work very well because it is generally not possible to tie the skin to a ski tightly enough to prevent snow from building up underneath the climbing skin. Furthermore, the numerous straps were time consuming to attach and keep properly adjusted. 
     More recently, adhesive climbing skins have been developed. Some adhesive climbing skins have a hook or the like which hooks over the tip of the ski. The skin is simply pressed against the ski base and is detachably held in place by a tacky adhesive. Such climbing skins provided acceptable performance when the base of the ski was dry. However, if the adhesive on the climbing skins becomes covered with snow or if the base of the ski becomes wet and has snow adhering to it then the adhesive may not properly hold the climbing skin to the base of the ski. In such cases, the climbing skin can become unstuck from the ski especially at the tail. 
     Climbing skins which use an adhesive as well as tail and tip straps to hold it in place have also become popular. This common tail fixation method is problematic in that it is usually necessary to modify the ski to provide a way to attach a strap to the tail end of the ski. Some current climbing skin systems have a fixture, such as a pin which is screwed into the top surface of the ski near the tail. A strap from the rear end of a climbing skin can then be stretched around the tail of the ski and attached to the pin. This is not desirable because it requires modification of the ski itself. 
     In another common tail fixation method, the skin is riveted to a pair of sandwiching metal plates that include an integral hook for engaging the tail end of the ski. Because the metal hook is relatively rigid, the strap must be moved to the tip end of the ski. Two rectangular metal wire looks (clips) are typically connected by a short (about 4 inches long) elastic, rubbery strip. The skin is fed through a portion of one of these separate clips and is looped back to adhere onto itself. The clip on the other end of the elastic strip is hooked over the tip of the ski to hold the skin in place. Having the elastic strip located at the tip can be a problem when the skier accidentally hits the wire loop with the opposite ski thereby knocking the clip completely off the tip of the ski. Once the skin is free from the tip of the ski, it can drag through the snow and the skin adhesive can become contaminated and eventually fail. 
     There is a need for an attachment system for climbing skins which allows climbing skins to be securely affixed by straps at both tip and tail ends of the ski and yet which is easy to use and does not require modification of the ski itself. 
     SUMMARY OF THE INVENTION 
     In one of its aspects, the present invention comprises a retention system for retaining a climbing skin to the tail end of a ski. The system includes an elongated resilient tensioning member, such as a strap, secured to one end of the skin. A separate, generally C-shaped clip is provided. The clip is adapted to removably hook about the tail end of the ski. Means are provided on an upper portion of the clip for releasably retaining and tensioning a portion of the strap on the clip. The clip provides a securement point for the strap and skin combination and is held by the tensioning effect of the strap. The arrangement is easily field serviceable and no permanent modification to the ski is required. 
     In another aspect of the invention, the clip has a flat base portion adapted to underlie the tail end of the ski, a vertical section adapted to extend behind the tail end, an angled portion extending from the vertical section at an acute angle in relation to the base portion and an upper portion extending from the angled portion and adapted to extend over the tail end. The upper portion includes an aperture sized to receive one end of the tensioning member therethrough. 
     In another aspect of the invention, there are provided a plurality of eyelets longitudinally spaced on the tensioning member, and a projection on the upper portion. The projection is sized to fit within the eyelets to retain the tensioning member on the clip. In a particular aspect of the invention, the upper portion comprises a portion having a generally apical shape having at least one downwardly extending leg and the aperture is located in the downwardly extending leg. 
     In yet another aspect, the invention comprises the method of attaching a climbing skin to the tail end of a ski, comprising providing a climbing skin attached to one end of a resilient tensioning member, hooking a generally C-shaped clip about said tail end of said ski such that a base portion of said clip underlies said tail end of said ski and an upper portion of said clip extends over said tail end of said ski and releasably securing a portion of said tensioning member to said upper portion of said clip so as to tension said clip in engagement about said tail end of said ski. 
     In a more particular aspect of the invention, the step of releasably securing the tensioning member to the upper portion of the clip involves threading that portion of the tensioning member through an aperture in the upper portion of the clip and engaging a projection on the upper portion into one of a plurality of eyelets longitudinally spaced on the tensioning member. 
     In yet a further aspect, the invention comprises a kit for a retention system for retaining a climbing skin on the tail end of a ski, comprising an elongated resilient tensioning member secured to one end of the skin, a generally C-shaped clip adapted to hook about said tail end, said clip having a flat base portion adapted to underlie said tail end, an angled portion extending at an acute angle in relation to the base portion and an upper portion extending from said angled portion and adapted to extend over the tail end, the upper portion being adapted to releasably retain one end of the member. 
     Other aspects of the invention will be appreciated by reference to the detailed description and to the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In drawings which illustrate various non-limiting embodiments of the invention: 
     FIG. 1 is a section through a climbing skin mounting system on the rear of a ski; 
     FIG. 2 is a top view thereof; 
     FIG. 3 is a section through an alternative embodiment of a clip which includes a jam nut; 
     FIG. 4 is a partially sectioned top plan view of a clip according to an alternative embodiment of the invention in which a cord lock device holds a cord under tension; 
     FIG. 5 is a schematic, partially cut-away top view of a mounting system according to an alternative embodiment of the invention which has a pair of cords held in a dual-cord cord lock; 
     FIG. 6 is a side elevation of a clip having a pin projecting from a location on its rear side; 
     FIG. 7 is a top view of a further alternative embodiment of the invention wherein a cord is held between a pair of spring-loaded cams; 
     FIG. 8 is a section through a further alternative embodiment of the invention wherein a strap is held by a tension lock; and 
     FIG. 9 is a side elevation of a clip according to an alternative embodiment of the invention wherein a strap passes through an upright flange on the clip. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 show a ski  10  to which is attached a climbing skin  12 . Elongated climbing skin  12  has a nap  13  made of rearwardly angled bristles and is attached to the base  10 A of ski  10  with a suitable removable adhesive  14 . An elongated tensioning strap  16  is affixed to the rear end of skin  12  as discussed in greater detail below. Strap  16  is affixed at the tail  10 B of ski  10  with a mounting clip  18 . 
     Mounting clip  18  is very generally C-shaped in cross-section and hooks around the tail  10 B of ski  10 . Clip  18  has a low rigid flat portion  15  which extends underneath the base  10 A of ski  10 . Clip  18  is rigid so that it can slide onto tail  10 B of ski  10  but cannot rotate when it is on ski  10 . Clip  18  may be made from any suitable material such as steel or a rigid plastic. Strap  16  has a number of longitudinally spaced apertures  17  in its distal portions. A user can apply tension to strap  16 , pull strap  16  around the rear end of clip  18  and then hold strap  16  in place on clip  18  by hooking one of apertures  17  around a projecting pin  20  on clip  18 . 
     In the preferred embodiment shown in FIG. 1, clip  18  has a raised portion  21  in which is an aperture  22 . Strap  16  passes through aperture  22 . Thus, clip  18  remains on strap  16  even when skin  12  and strap  16  are removed from the ski  10 . The shape of clip  18  tends to prevent clip  18  from rotating relative to tail  10 B of ski  10  under the tension forces exerted on strap  16 . The strap  16  exerts a net forward pulling force on clip  18 , i.e. it exerts a net force inward from the tail end  10 B of the ski. This net force acts to retain clip  18  in engagement about the tail end of the ski. 
     Preferably the rear portion  26  of clip  18  has a short vertical surface adapted to extend upward behind the tail end of the ski, and a surface  26 A extending from the top of the vertical surface and which is disposed at an acute angle relative to base portion  15 . Thus, when clip  18  is installed and strap  16  is under tension, the tail end  10 B of ski  10  is wedged into the rear end of clip  18  between surface  26 A and lower portion  15  of clip  18 . This tends to prevent clip  18  from sliding sideways in either direction on the tail  10 B of ski  10 . 
     Unintentional rotation of the clip  18  about the tail end  10 B of the ski is prevented by the bracing effect of the base portion  15  of the clip  18  that underlies the ski and by the angled surface  26 A abutting against the corner of the tail end. It will be appreciated that the length of the base portion  15  and the angle of the surface  26 A can be chosen to nonetheless allow intentional removal of the clip by the user pulling the strap rearward of the ski. 
     Preferably strap  16  and/or skin  12  are slightly resilient so that skin  12  and strap  16  remain under tension while in use. Strap  16  may be made from a strip of fabric-reinforced rubber, or the like. Most preferably, the rearmost end  19  of strap  16  is broadened. This both prevents the accidental removal of clip  18  from strap  16  and provides a convenient hand grip for applying tension to strap  16  when attaching skin  12  to a ski. 
     In the embodiment shown in FIGS. 1 and 2, the strap  16  is releasably affixed to clip  18  by means of a pin  20  on clip  18  which is received through an aperture  17  in strap  16 . Other suitable means for holding the strap  16  is a tensioned manner to clip  18  may also be used. For example, as shown in FIG. 3, clip  18 A may include a jam lever  30  which can be pressed down so as to hold strap  16  in place on clip  18  by compressing a strap between a cam  31  and a surface  32  on clip  18 A. Jam levers are known in the art and can be readily purchased from various sources. Preferably the jam lever  30  is installed so that tension on strap  16  tends to tighten the cam, and thereby prevent strap  16  from becoming loose during use. 
     As shown in FIG. 4, strap  16  could comprise a cord instead of a flat strap or could comprise a flexible flat member having a cord attached to its end. In the embodiment of FIG. 4, a cord  32  attached to a climbing skin passes around the rear end of clip  18 B to be held in place on clip  18 B by a cord lock device  34 . Cord lock devices  34  of various types are well known in the art. The type of cord lock device shown in FIG. 4 has a plug  35  slidably mounted within a housing  36 . Plug  35  is biased toward one side of the housing  36  by a spring  37 . Cord  32  passes through apertures  38  in the housing and the plug and is jammed between the plug and the housing. A release button  39  allows a user to displace the plug  35  against the bias force exerted by the spring  37  to release the cord  32 . Cord lock device  34  is preferably of a type which is designed in such a manner that tension on cord  32  tends to tighten the cord lock device  34 . 
     FIG. 5 shows a clip  18 C in which a skin  12  is tensioned on a ski  10  with a dual-cord cord lock  40 . Cords  32  pass between a wedge  42  and inclined walls  43 . Tension on cords  32  tends to pull wedge  43  rearwardly, thereby tightly gripping cords  32 . The angles of walls  43  relative to the longitudinal center of clip  18 C are exaggerated in FIG.  5 . In the FIG. 5 embodiment cords  32  pass around locating grooves in the rear end of clip  18 C. Locating grooves  44  guide cords  32 . 
     When a strap is affixed to a clip  16  by a way of a tab which projects through a hole in the strap, it is not necessary that the tab be located in the same position shown in FIGS. 1 and 2. FIG. 6 shows a clip  18 D according to an alternative embodiment wherein a tab  20 A projects generally rearwardly from clip  18 . This embodiment is not preferable because of the enhanced likelihood that strap  16  may become accidentally dislodged from tab  20 A in the FIG. 6 embodiment during use. 
     FIG. 7 shows a further alternative embodiment wherein a cord  32  which is attached to the rear end of a climbing skin passes around clip  18 E and is held in place while tensioned between a pair spring-loaded cams  46 . Larger versions of such cams are used, for example, to secure ropes on sailing boats. 
     FIG. 8 shows a clip  18 F according to a further alternative embodiment wherein a strap  16  is held in place by a tension lock assembly  50 . Tension locks are well known and are commonly used to adjust the lengths of straps on backpacks. In a tension lock, a strap is doubled back on itself around a number of surfaces tending to resist slippage. 
     As described above, in preferred embodiments the clip  18  is slidably disposed on the strap or cord which is attached to skin  12 . This prevents clip  18  from becoming lost when skin  12  is detached from ski  10 . The embodiment of FIGS. 1 and 2 shows the strap  16  passing through a pair slots on either side of a bend in the upper portion of clip  18 . Clip  18  could be configured in any of various alternative ways which also cause clip  18  to be slidably disposed on a strap or cord when the skin is detached from a ski. For example, FIG. 9 shows a clip  18 G wherein a strap or cord passes through an aperture  55  in a flange  56  which projects upwardly from a top surface of clip  18 G. A strap or cord could also pass through a loop of cord or elastic attached to a clip  18 . 
     While it is not preferred, a strap  16  could also be held to the top of clip  18  by a section of hook and loop fastener material such VELCRO™, having one part on the clip and another part on the strap. A strap or cord could also be retained on a clip  18  by a snap fastener, mechanical clamp, or the like. Where a mechanical clamp is used a user could pull a strap or cord tight and then secure the strap or cord in place by turning a screw or the like. 
     It will be appreciated that while the embodiments of the invention have been described in some detail, modifications and alterations thereto may be practiced without departing from the scope of the invention.