Patent Publication Number: US-9409079-B2

Title: Dry-land alpine skis

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent document claims priority to U.S. provisional patent application Ser. No. 61/930,028, filed Jan. 22, 2014 and entitled “DRY-LAND ALPINE SKIS”, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to modified alpine skis and snowboards for use on dry-land surfaces, and more specifically to modified alpine skis and snowboards having a plurality of angled wheels. 
     BACKGROUND 
     Alpine skiing (also known as downhill skiing) and snowboarding are popular sports and hobbies shared by millions of people throughout the world. Typically, however, these sports require access to expensive sporting hardware and winter clothing and travel to select regions, as alpine skiing and snowboarding require cold climates and high elevations to create the requisite snow surface on an inclined trail (for example, on hills and/or mountains) necessary for downhill skiing or snowboarding. 
     Alpine skiing is typically characterized by skis with fixed-heel bindings. Generally, alpine skis are not used for walking or hiking, unlike cross-country skis which are typically characterized by free-heel bindings. However, some alpine skiers employ poles for assistance with short distance locomotion, walking, skating, steering, balance, etc. Typically, alpine skiers rely on mechanical assistance to reach the top of a hill. At ski resorts, services such as ski lifts are provided, while back-country skiers rely on helicopters or snowcats, if not hiking, to transport them to a ski site. These forms of assistance in snowy regions can be cost-prohibitive, subject to narrow time windows, and time-consuming, particularly during a region&#39;s “busy season”. 
     Snowboarding is typically characterized by a board which glides downhill on snow and on which the snowboarder stands with feet substantially transverse to the longitude of the board. Commercial snowboards generally require equipment such as bindings and special boots which secure both feet of a snowboarder to the board. As with alpine skis, snowboards are generally not used for walking or hiking, and snowboarders generally rely on mechanical assistance to reach the top of a hill. 
     SUMMARY OF THE INVENTION 
     Embodiments described herein provide a wheeled device, and method of making thereof, that simulates the feel and performance of alpine skiing/snowboarding on dry land. Features of embodiments include: (1) a deck having flex similar to that of a ski/snowboard; (2) placement of wheels in a geometry mimicking the side cut of a shaped alpine ski/snowboard, and that with feature (1), enables a user to turn the device in an arc; and (3) wheels constructed of materials of varied coefficients of friction, which enable a user to skid the device in a braking mechanism similar to that of an alpine ski/snowboard, with the placement and design of the wheels emulating the base edge bevel of a typical alpine snow-ski/snowboard. In an embodiment, the device is affixed to a user&#39;s feet using a binding device similar to that used for alpine skiing/snowboarding, and the user primarily relies on gravity on an inclined plane for locomotion. 
     A first aspect of the present invention includes a wheeled ski device, the device comprising: a base board, the base board including an elongated structure having a top surface and a bottom surface and having a transitional point on a longitudinal axis of the elongated structure; and a plurality of opposing pairs of wheels coupled to opposite edges of the elongated structure at various points along the longitudinal axis of the elongated structure, wherein an axis of each wheel is set at a first angle relative to an x-y plane that is positive relative to the top surface, the plane formed by the longitudinal axis of the base board and a lateral axis of the base board; and wherein the axis of each wheel is further set at a second angle relative to an y-z plane of the base board that is open towards the transitional point, the plane comprising the longitudinal axis and perpendicular to the y-z plane. 
     Another aspect of the present invention includes a method of making a wheeled ski device, the method comprising: affixing a plurality of opposing pairs of angled axels to opposite sides of a longitudinal axis of an elongated structure of a base board at various points along the longitudinal axis of the elongated structure, the base board having a transitional point on the longitudinal axis of the elongated structure; and affixing a wheel to each axel, wherein each axel is set at a first angle relative to an x-y plane that is positive relative to a top surface of the base board, the plane formed by the longitudinal axis of the base board and a lateral axis of the base board; and wherein the axel is further set at a second angle relative to an y-z plane of the base board that is open towards the transitional point, the plane comprising the longitudinal axis and perpendicular to the y-z plane. 
     Yet another aspect of the invention includes a method of using a wheeled ski device, the method comprising: moving a wheeled ski device having a base board including an elongated structure and having a transitional point on a longitudinal axis of the elongated structure, and a plurality of opposing pairs of wheels coupled to opposite edges of the elongated structure at various points along the longitudinal axis of the elongated structure, wherein an axel of each wheel is oriented at a positive angle above a horizontal plane relative to a top surface of the base board and at an angle facing towards the transitional point relative to a vertical plane comprising the longitudinal axis and perpendicular to the horizontal axis that decreases with distance from the transitional point; engaging a side of the wheeled ski device by turning the wheeled ski device on a side; causing the wheeled ski device to turn in an arc in response to engaging the side; disengaging the side of the wheeled ski device by reorienting the wheeled ski device; and causing the wheeled ski device to skid in response to disengaging the side. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings in which: 
         FIG. 1  depicts a set of alpine snow skis according to an embodiment of the present invention; 
         FIG. 2  depicts the geometry of an alpine ski edge-arc according to an embodiment of the present invention; 
         FIG. 3  depicts a cross-section of an alpine snow ski with expanded view of a base bevel according to an embodiment of the present invention; 
         FIG. 4  depicts a carving ski in motion according to an embodiment of the present invention; 
         FIG. 5  depicts illustrative examples of alpine ski tracks relative to an amount of skid employed by a user according to embodiments of the present invention; 
         FIG. 6  depicts a dry-land ski device according to an embodiment of the present invention; 
         FIGS. 7A-7C  depict views of (a) wheels in line, (b) wheels emulating the edge geometry of an alpine snow ski, and (c) an alpine snow ski according to an embodiment of the present invention; 
         FIGS. 8A-8D  depict illustrative examples of wheel assemblies of the dry-land ski device according to embodiments of the present invention; 
         FIGS. 9A-C  depict illustrative examples of truck assemblies according to embodiments of the present invention; 
         FIG. 10  depicts a cross-section of the dry-land ski device at a truck location according to an embodiment of the present invention; 
         FIGS. 11A and 11B  depict a wheel of the dry-land ski device according to an embodiment of the present invention; and 
         FIGS. 12A and 12B  depict a simulated time-lapse series of a dry-land ski device in motion according to embodiments of the present invention. 
     
    
    
     The drawings are not necessarily to scale. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. The drawings are intended to depict only typical embodiments of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements. 
     DETAILED DESCRIPTION 
     Illustrative embodiments will now be described more fully herein with reference to the accompanying drawings, in which exemplary embodiments are shown. It will be appreciated that this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these illustrative embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of this disclosure to those skilled in the art. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments. 
     Furthermore, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, the use of the terms “a”, “an”, etc., do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The term “set” is intended to mean a quantity of at least one. It will be further understood that the terms “comprises” and/or “comprising”, or “includes” and/or “including”, when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments of this invention are directed toward providing a dry-land alpine skiing device that simulates the turning curvature and sliding components of an inclined snow surface alpine skiing experience, but on a dry-land inclined surface. Accordingly, as indicated above, a wheeled device, and method of making thereof, that simulates the feel and performance of alpine skiing/snowboarding on dry land is provided herein. Features of embodiments include: (1) a deck having flex similar to that of a ski/snowboard; (2) placement of wheels in a geometry mimicking the side cut of a shaped alpine ski/snowboard, and that with feature (1), enables a user to turn the device in an arc; and (3) wheels constructed of materials of varied coefficients of friction, which enable a user to skid the device in a braking mechanism similar to that of an alpine ski/snowboard, with the placement and design of the wheels emulating the base edge bevel of a typical alpine snow-ski/snowboard. In an embodiment, the device is affixed to a user&#39;s feet using a binding device similar to that used for alpine skiing/snowboarding, and the user primarily relies on gravity on an inclined plane for locomotion. 
     Embodiments of the invention modify alpine skis and snowboards to enable a user&#39;s recreational or sporting experience on a dry inclined surface to emulate those of typical alpine skiing. As used herein for the purpose of describing particular embodiments, the terms “alpine skiing”, “skiing”, “downhill skiing”, “monoskiing”, “alpine touring skiing”, “downhill snowboarding”, “snowboarding”, “boarding” and the like, may be used interchangeably to refer to the act of alpine skiing and/or snowboarding, and are not intended to be limiting. Furthermore, as used herein for the purpose of describing particular embodiments, the terms “alpine ski”, “ski”, “downhill ski”, “carving ski”, “snow ski”, “monoski”, “alpine touring ski”, “downhill snowboard”, “snowboard”, “board” and the like, may be used interchangeably to refer to an alpine ski and/or snowboard, and are not intended to be limiting. 
     Referring now to  FIG. 1 , a set of alpine snow skis according to an embodiment of the present invention is depicted. In a typical embodiment, each individual ski  102  comprises a flat board that is a composite construct of one or more of wood, fiberglass, plastic, and metal and bound by a bonding agent such as epoxy resin. The ski has a top, a bottom, a front  106 , a rear  108 , and a midpoint  110 . The width “x” and thickness “z” of the skis  102  is variable based on the performance needs of the ski and the manufacturer&#39;s construction. The length “y” of ski  102  provides stability. A user selects a ski length that is consistent with the user&#39;s ability level and style of skiing. A longer ski provides more stability, but is also more difficult to control. Ski  102  also has “flex,” the ability to bend. Flex allows ski  102  to bend along the y-z plane in order to engage an edge of ski  102  with the ground. Each ski  102  is mechanically attached to the user, typically via a ski binding and a ski boot (not shown). Skis of a pair are identical to one another. 
     Front tip  106  of ski  102 , called the “shovel”, is typically pointed or rounded and turned up so the device will stay on top of a snowy surface. Ski rear  108 , called the “tail”, is typically flat and square. Shovel  106  and tail  108  are in most cases wider than the ski midpoint  110 , called the “waist”. An imaginary line that bisects the longitudinal plane of ski  102  may be described as ski centerline  112 . The distance from ski centerline  112  to a side edge  104  of ski  102  is called the “edge offset distance”  114 . As the ski width is variable, the edge offset distance is also variable along the body of ski  102 . For example, edge offset distance  114 A and  114 C at shovel  106  and tail  108 , respectively, of ski  102  are wider than edge offset distance  1148  at waist  110  of ski  102 . Ski  102  is symmetric across centerline  112 , therefore each edge  104  is a mirror image of its opposite. 
     The shape of ski edge  104  is referred to as the ski “side cut”. The side cut is typically a curve, based on a circle of radius “R”, which typically ranges from 8 meters to 55 meters, depending on the performance characteristics the skier chooses. Referring now to  FIG. 2 , the x-y plane view of an alpine ski (pictured from the bottom), superimposed against the circumference of a circle of radius “R”, that specifies the geometry of the ski edge-arc, is depicted. As seen in  FIG. 2 , when fully engaged with the ground, the minimum circle ski  102  can turn upon is circle  200  of radius “R”. Referring back to  FIG. 1 , tangents  118 A-C to circle  200  are shown along ski edge  104  to further illustrate the congruence of curve of ski edge  104  with the curve of circle  200 . 
     Referring now to  FIG. 3 , a cross-section of an alpine snow ski in the x-z plane is depicted.  FIG. 3  further shows a magnification of the edge section of an alpine snow ski in order to demonstrate how “base bevel” is built into the edge of an alpine ski. Generally, base  320  of ski  102  (i.e., the portion of ski  102  in contact with the ground) is flat, with the exception of base edges  322 . Typically, the entire length of base edges  322  are lined with steel that is ground or sharpened to a relatively sharp chisel blade edge  324 . Steel blade edge  324  is cut such that when viewing the ski cross-section, steel blade edge  324  lies at an upward, acute angle, “Φ”, relative to the horizontal (x-y) plane; this angle is referred to as the edge angle or base bevel. Typically, recreational skies are set at 1° of base bevel (Φ=1° from horizontal), whereas racing skis are typically set at 0.5° to 0.75° of base bevel (Φ=0.5° to 0.75° from horizontal). As base bevel decreases, ski  102  becomes more responsive. To an inexperienced skier, a smaller degree of base bevel can result in a ski that is more “grabby” and more difficult to control. At 0° of base bevel, the edge runs flush with the base of the ski and the ski has the potential to catch on the wrong edge and throw the rider. 
     A snowboard possesses similar mechanics and structure to the ski, with the exception that the user is transported on a single deck. The user&#39;s feet are mechanically affixed to a single board via bindings and the user stance is typically sideways to the board. The board likewise has a tip, tail, waist, and side cut similar to a ski. 
     The sport of alpine skiing/snowboarding includes two basic mechanisms of performance: (1) flexibility, which enables an edge of the ski/board to track in the snow; and (2) the ability to skid turns. 
     Referring now to  FIG. 4 , a carving ski in motion, as viewed in the x-y-z planes, is depicted. Generally, skis/boards are designed with a concave edge shape (i.e., the “side cut”) which permits ski  102  to bend or flex when rolled up onto edge  104  (e.g., during a turn while skiing). As discussed above, ski  102  is wider at tip  106  and tail  108  than at waist  110 . Therefore, when rolled up on edge  104 , the only two points of ski  102  which would be in contact with the ground are tip  106  and tail  108 . However, under a ski user&#39;s weight and centripetal force from a turn, ski  102  is forced to bend for midpoint  110  to remain in contact with the ground. In other words, as ski  102  is rolled on edge  104 , the ski bends in order for edge  104  to maintain contact with the ground. Furthermore, as ski  102  is rolled on edge  104  more aggressively (e.g., from 40° to 60° above the x-y plane), the ski bends further. 
     The mechanism described above permits ski  102  to track in the snow along edge  104 , which is in contact with the ground or, more specifically, a snowy surface. The amount of bend produced in ski  102  determines the curvature of the track of ski  102 , because ski  102  tracks along the concave shape of bent ski  102  in arc  416 . As discussed further below with reference to  FIG. 5 , if ski  102  does not slide away (i.e., skid) from the ski track, then ski  102  tracks exactly along the arc  416  of ski  102 , without deviation. In this case, the user is performing a pure carve, in which ski  102  should be accelerating with no slippage of ski edge  104 . 
     Referring now to  FIG. 5  (in addition to  FIG. 4 ), illustrative examples of alpine ski tracks relative to an amount of skid employed by a user according to embodiments of the present invention are shown. As discussed above, the second mechanism for ski performance is the ability to skid turns. Skidding allows a ski user to decelerate, for example, for speed control. Skidding occurs when the user places less pressure on ski  102 , allowing the grip of edge  104  to be released from the snow/ice or other ground surface. While ski  102  is guided along ski arc  416  based on the curved shape of ski  102 , a centripetal force also pulls ski  102  at a tangent to ski arc  416 . Accordingly, there are two paths associated with the motion of ski  102 : along ski arc  416  and along the tangent to ski arc  416 . Accordingly, a ski that skids produces a wider track in the snow. Furthermore, track size is directly proportional to the degree the user skids the ski. For example, as seen in  FIG. 5 , time-lapse snapshot  532  of a ski in motion shows a ski with no skid angle (i.e., a pure carve) traveling in the direction of arrow  533 . This time-lapse corresponds with ski track  534  which produces a thin curved line. In another example, time-lapse snapshot  536  of a ski in motion shows a ski with a small skid angle traveling in the direction of arrow  537 . This small-angle time-lapse corresponds with ski track  538  which produces a narrow track width. In still another example, time-lapse snapshot  540  of a ski in motion shows a ski with a large skid angle traveling in the direction of arrow  541 . This large-angle time-lapse corresponds with ski track  542  which produces a wide track width. 
     Referring now to  FIG. 6 , a dry-land ski device according to an embodiment of the present invention is shown. Dry-land ski device  600  may be used to “ski” down inclines on non-snow surfaces such sidewalks, asphalt, dirt tracks, grass fields, etc. In some embodiments, dry-land ski device  600  comprises ski base or “deck”  602  upon which a plurality of wheels  604  is affixed via rigid trucks  606 . In some embodiments, deck  602  may be an alpine ski. In other embodiments, deck  602  may be any elongated structure similar to an alpine ski, snowboard, etc. In any case, deck  602  is configured to have the flex and length of an alpine ski. As will be discussed in more detail further below, wheels  604  are angled and arranged in pairs on opposite sides of deck  602  so as to mimic the geometry of a typical alpine ski edge. This arrangement permits dry-land ski device  600  to roll to one side on angled wheels  604 , emulating a ski bending on its side. In some embodiments, trucks  606  may be attached to a top surface of deck  602 . In some other embodiments, trucks  606  may be attached to a bottom surface of deck  602  or to a side surface of deck  602 . The location of trucks  606  with respect to deck  602  shown in  FIG. 6  is not intended to be limiting. Although not depicted in  FIG. 6 , embodiments of dry-land ski device  600  may comprise a binding or boot/shoe/foot attachment at site  608 , as is typically employed to attach alpine skis to a user&#39;s feet. 
     Referring now to  FIGS. 7A-7C , a view of wheels emulating the edge geometry of an alpine snow ski according to an embodiment of the present invention is depicted. The inventor has discovered that many people use inline skates for practicing skiing when on dry land; however, these do not provide an accurate emulation of skiing, because inline skate wheels are rigidly aligned in a straight line, as shown in wheel line model  712 , synonymous with the blade of an ice skate. Therefore, an inline skate device is locked in a linear motion and is less stable than a ski as the wheel base (blade length) is short. Although a ski centerline is homologous to an inline skate wheel arrangement, the inventor has discovered that arranged and angled wheels on opposite sides of a ski-like deck, as presented in embodiments of the present invention, present a much improved emulation of the alpine skiing experience in non-alpine settings. 
     As discussed above with respect to  FIG. 2 , alpine skis travel in an arc due to the curved edge geometry of the alpine skis when an edge of the ski is engaged with the ground. Accordingly, in some embodiments of the present invention, dry-land ski device  600  ( FIG. 6 ), emulating the edge geometry of an alpine snow ski, as shown in wheel geometry model  714 , is provided. In some embodiments, dry-land ski device  600  is configured to track based on the geometry of angled and arranged wheels  604 . Therefore, when wheels  604  on one side of dry-land ski device  600  are tipped up on the edge of said wheels, the wheels are said to be engaged on the ground, and dry-land ski device  600  travels in an arc. 
     With reference to both  FIGS. 6 and 7 , in some embodiments, wheels  604  are arranged to replicate the mechanics of a snow ski. As opposed to the wheels of an inline skate, wheels  604  are aligned to mimic the “side cut” geometry of a ski edge, rather than the ski centerline. Accordingly, wheels  604  only run parallel to a ski centerline (e.g., center model wheel  718  that runs parallel to ski centerline model  716 ) if, in some embodiments, located at the waist of deck  602 , which is analogous to waist  110  of ski  102  ( FIG. 1 ), where tangent  118  to the arc of ski edge  104  runs parallel to centerline  112 . In some embodiments, wheels  604  at all other locations along deck  602  run at a slight angle relative to the centerline, parallel to tangent  118  to the arc of ski edge  104  of analogous ski  102  ( FIG. 1 ). This is shown as angled model wheel  720 , which angles away from ski centerline model  716  along an arc tangent. This angled wheel arrangement enables a side set of wheels  604  to travel in an arc when dry-land ski device  600  is tipped on its side. 
     By contrast, when dry-land ski device  600  is in a neutral position (i.e., all wheels  604  contact the ground simultaneously) dry-land ski device  600  tracks in a straight line (i.e., the direction of the longitudinal centerline). Device  600  travels in a straight path because the lateral pull of the wheels on opposing edges of device  600  effectively cancel each other out. This matches the behavior of an alpine ski which, as shown in ski line model  606 , tracks in a straight line (i.e., the same direction as the ski centerline) when the ski lies in a neutral position flat against the ground. 
     Referring now to  FIGS. 8A-D , illustrative examples of wheel assemblies of the dry-land ski device according to embodiments of the present invention are depicted, and more specifically,  FIGS. 8A-D  depict (a) an x-y plane view of a simple front, middle, and rear wheel assembly configuration of an embodiment of the present invention, (b) an x-y plane view of a full wheel assembly of one embodiment of a dry-land ski device, (c) a side view of a full wheel assembly of one embodiment of a dry-land ski device, and (d) an x-y plane view of a full, six-truck wheel assembly of one embodiment of a dry-land ski device, as mounted on an alpine ski, if using the ski as the deck of a dry-land ski device. 
     A first ski-like feature of embodiments of the invention is the geometry of wheel axels  810  of trucks  806  relative to longitudinal axis/centerline  812  of dry-land ski  802 , which permit a dry-land ski device to mimic the flexibility and side bending of an alpine ski. Dry-land ski  802  may be a base board or deck such as an alpine ski or a structure similar to an alpine ski. Although not pictured, dry-land ski  802  may comprise a binding or boot/shoe/foot attachment site at midpoint  808  of ski  802 . 
     The configuration geometry is best understood in reference to centerline  812  and transitional point  814 . In some embodiments, one or more pairs of wheels  804  are arranged along the length of dry-land ski  802  with trucks  806  having axels  810  with specific geometry relative to centerline  812 . In one embodiment, the truck/wheel placement positions are (1) at or about the tip of ski  802 , (2) halfway between the tip and ski midpoint, (3) near the ski midpoint just ahead of the binding or boot/shoe/foot attachment, (4) near the ski midpoint, just behind the binding or boot/shoe/foot attachment, (5) halfway between the ski midpoint and tail, and (6) at or about the ski tail. This truck/wheel placement presents merely one embodiment of the present invention and is not intended to be limiting; it is envisioned that embodiments of dry-land ski device may comprise any plurality of wheels  804 . 
     In any case, at each position or truck  806 , a wheel  804  is placed on each of two edges or axels  810 . As discussed above, each wheel  804  is placed such that it sits parallel to tangent  118  of the arc of ski edge  104  of analogous ski  102  ( FIG. 1 ), where the arc is an imaginary curve that describes circle  200  of radius “R” ( FIG. 2 ). Therefore, as opposed to running parallel with centerline  812 , wheels  804  run tangential to the arc of the ski edge being emulated. This is achieved by the geometry of axels  810  of trucks  806 . Axels  810  are configured to be perpendicular to tangent  118  of the arc of ski edge  104  of analogous ski  102  ( FIG. 1 ) for a given position along dry-land ski  802 . This geometric arrangement may be further described by viewing dry-land ski  802  from above in the x-y plane, as seen in  FIGS. 8A, 8B, and 8D . Some embodiments of dry-land ski  802  comprise transitional point  814 , a point on centerline  812  where tangent  118  of the closest point of the arc of ski edge  104  of analogous ski  102  ( FIG. 1 ) is parallel to the centerline. In other words, for either longitudinal side of dry-land ski device  802 , an axel at transitional point  814  would be perpendicular to centerline  812 , and heading outward from transitional point  814  along centerline  812 , axels  810  form increasingly small acute angles with centerline  812  facing towards transitional point  814 . Accordingly, transitional point  814  is the point around which axels  810  on a longitudinal side of ski device  802  rotate from pointing in a positive “y” direction to a negative “y” direction. 
     Referring now to  FIGS. 9A-C , illustrative examples of trucks according to embodiments of the present invention are depicted. Relative to the horizontal (i.e., the x-y plane or a top surface of deck  602  ( FIG. 6 )), wheels are set with camber (i.e., an acute angle at which wheel axle  910  is set, relative to the dry-land ski base, itself set at a relative 0°). A wheel whose axle is co-planar to the ski base is described as having zero degrees (0°) of camber or no camber. In some embodiments, the camber of axel  910  relative to the horizontal ranges from about 30° to 60°. For example, axel  910 A of truck  906 A is set at a camber of about 30° (⊖ A =30°). In another example, axel  9108  of truck  906 B is set at a camber of about 60° (⊖ B =60°). In still yet another example, axel  910 C of truck  906 C is set at a camber of about 45° (⊖ c =45°). In some embodiments, camber may be varied along a length of the dry-land ski device; for example, in one embodiment, wheels may be set with a camber of about 30° near a middle of a ski deck, and set with a camber of about 45° near each end of the ski deck. In embodiments such as those employing trucks  906 , wheels are “cantilevered” up and outward relative to a dry-land ski deck. In some embodiments, axels  910  may be supported, for example, by support structure  912 B which extents between two separated axels, or by support structure  912 C which extents between two touching axels. In some embodiments, truck  906  may be bound to a deck of a dry-land ski device using methods generally known in the art, such as rivets, nails, screws, clamps, glue, adhesive, chemical bonding, and the like. 
     Referring now to  FIG. 10 , a cross-section in the x-z plane of the dry-land ski device at a truck location according to illustrative embodiments is depicted. Edge offset distance (the distance from a ski centerline to a side edge) is incorporated into embodiments of the dry-land ski device via the truck geometry. As discussed above with respect to  FIG. 1 , as ski width varies along the body of a ski, the edge offset distance also varies, with the waist of the ski typically having a smaller edge offset distance than the shovel and tail. In some embodiments, wheel axle  1010  is set at a distance from centerline  1012  of deck  1002  (e.g., assuming an alpine ski as a deck, the narrowest offset position is at the ski waist). This may be described as the simulated edge offset distance of the dry-land ski device. The distance of axel  1010  from centerline  1012  is based on point  1016  at which wheel  1004  contacts the ground. Point of contact  1016  in turn is determined by edge offset distance of deck  1002 , the amount of camber ( 0 ) built into axel  1010 , and the dimensions of wheel  1004 . Accordingly, in some embodiments, in order to yield a desired simulated edge offset distance  1014 , any one of width of deck  1002 , camber (⊖) of axels  1010 , and dimensions of wheels  1004  may be modified along the length of the dry-land ski. 
     Referring now to  FIG. 11A , a wheel of the dry-land ski device according to an embodiment of the present invention is depicted. A second ski-like feature of embodiments of the invention is a wheel construction, which permits a dry-land ski device to skid, mimicking skidding of an alpine ski. As discussed above, skidding is the primary form of speed control in alpine skiing, a critical function particularly when the skiing surface slope steepness increases. Accordingly, in some embodiments, the dry-land ski device employs a wheel construction which permits a user to skid to, inter alia, control their speed. 
     In a typical embodiment, wheel  1120  employs a composite of materials with varied coefficients of friction that effectively emulate metal edge  324  of ski  102  ( FIG. 3 ). Polyurethane wheels typically used for inline skates generally are composed of a homogeneous polyurethane compound and therefore, in some embodiments, do not provide an appropriate variance of the coefficient friction to allow both proper skid and edge grip. In some embodiments, construction of wheel  1120  incorporates material with an ultra-low coefficient of friction and exceptional toughness and durability, such as ultra-high molecular weight polyethylene (UHMWPE), built into a matrix of a polyurethane substrate. In some embodiments, polyurethane substrate is constructed of striated and variable-durometer (i.e., hardness) polyurethane (or a similar substance). In one such embodiment, a gradient of hardness is designed into wheel  1120 , such that rear side  1124  of wheel  1120  may transition from an ultra-low coefficient of friction material (e.g., UHMWPE), to a very hard, low coefficient of friction polyurethane (such as with a durometer of 101 A), at interface  1128 . Front side  1122  may then continue to progress to a successively lower durometer material (e.g., polyurethane) with corresponding progressively higher coefficients of friction. In some embodiments, the point at which wheel  1120  transitions to higher coefficient of friction materials is described as interface  1128 . Wheel  1120  may be constructed around a hub or bearing  1126  of any material currently known in the art. 
     Referring now to  FIGS. 11A and 11B , interface  1128  between a material with a low coefficient of friction (e.g., UHMWPE) at rear side  1124  and a material with a higher coefficient of friction (e.g., polyurethane) at front side  1122  is determined based on amount of camber “⊖” at which truck axel  910  ( FIG. 9 ) (see also axel  1010  of  FIG. 10 ) is set. Edge angle “⊖” is defined as the angle between point of contact with ground  1130  of wheel  1120  and interface  1128 , relative to edge curvature  1132  of wheel  1120 . Distance “x” between point of contact with ground  1130  and interface  1128  simulates edge base bevel of analogous alpine ski  102 . 
     Referring now to  FIGS. 12A and 12B , as well as  FIG. 11 , a simulated time-lapse series of a dry-land ski device in motion according to embodiments of the present invention is depicted. Harder plastic and rubber compounds typically have lower coefficients of friction than their softer counterparts. Accordingly, a harder wheel in contact with a surface will have more slip. For example, in the embodiments discussed above, when the dry-land ski device is in neutral position  1242  (i.e., flat against the ground), only rear side  1124 , the portion of wheels  1120  constructed of an ultra-low coefficient of friction material, contacts the ground. In some of the embodiments described above, as a user engages an edge of the dry-land ski device by rolling the device up on edge, the ground contact point of wheel  1120  transitions (as seen at position  1244 ) to front side  1122 , made of a softer material with a higher coefficient of friction (as seen at position  1264 ). At position  1246 , wheel grip is considerably improved because area of wheel  1120  in contact with the ground is made of a high coefficient of friction. On the other hand, as a user releases an edge of the dry-land ski device and returns the device to a neutral position, wheel  1120  engages rear side  1124 , and progressively harder materials with correspondingly lower coefficients of friction, in contact with the ground. These movements enable a user to skid the dry-land ski device. 
       FIG. 12A  depicts a simulated time-lapse series of pictures  1240  of a cross-sectional view in the x-z plane of a truck/wheel assembly as mounted to base  1250 , according to embodiments of the present invention, where the angle of the dry-land ski device is increased as it engages softer wheel portions as edge angle increases.  FIG. 12B  likewise depicts simulated time-lapse  1248  of a cross-section of snow ski  1252  as the ski is tipped on edge, increasing edge angle to engage the edge of the ski. As seen in time lapses  1240  and  1248 , base  1250  of the dry-land ski device of embodiments of the present invention mimics the same tilting motion as ski  1252 . Accordingly, the dry-land ski device of embodiments of the present invention presents a much improved emulation of the alpine skiing experience in non-alpine settings. 
     Further embodiments of the present invention are envisioned. In one embodiment of the invention, an alpine ski or similar base is permanently made or modified with the wheel and truck assemblies described in embodiments of the present invention. In this embodiment, wheel and truck components are permanently attached to an alpine ski and boot device, or ski-like device (e.g., a snowboard), to create a permanent dry-land skiing device. In another embodiment of the invention, an alpine ski or similar base is temporarily modified with the wheel and truck assemblies described in embodiments of the present invention. In this embodiment, wheel and truck components are temporarily attached to an alpine ski and boot device, or ski-like device (e.g., a snowboard), to create temporary dry-land skiing devices. In the embodiments described above, these modifications may be achieved using methods generally known in the art, such as rivets, nails, screws, clamps, glue, adhesive, chemical bonding, temporary adhesives, and the like. 
     It is apparent that there has been provided with this invention a modified alpine ski for use in non-alpine conditions such as on a dry-land inclined surface. While the foregoing description of various aspects of the invention has been presented for purposes of illustration and description, it is not intended to be exhaustive or to limit the invention to the precise form disclosed. It will be appreciated that variations and modifications will occur to those skilled in the art in light of the description. Accordingly, it is to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.