Patent Application
20120256395
Backcountry snowboarding appeals to riders who wish to ride untracked snow, avoid the crowds of commercial resorts, and spurn limitations on what and where they can ride. There are no ski-lifts in the backcountry, so the snowboarder must climb the slopes by physical effort. Some snowboarders simply carry their board and hike up, but progress can be almost impossible if the hiker sinks deep in soft snow. Travel efficiency can be improved with snowshoes, but the rider must still find a way to carry their board up the slope.
Saving effort is the name of the game in the backcountry; it determines how many runs a rider is going to make in a day. If riders are exhausted by the time they reach the top of the run, they aren't going to snowboard to the best of their ability, or enjoy themselves as much as they could.
Splitboards are a recent improvement. When assembled, a splitboard looks like a snowboard, but can be taken apart to form a pair of skis. The right and left “skis” of a splitboard are asymmetrical; i.e., they are the mirror halves of a snowboard—longitudinally cut (or “split”), and typically have the sidecut (ie. nonlinear long edges) and camber of snowboards.
When touring cross-country and uphill to reach the slopes, the skis are worn separately. Cross-country travel on skis requires less effort than hiking or snowshoeing. Since the rider is wearing the skis instead of carrying a snowboard, the effort is less tiring—the rider can glide along, and there is no extra weight to carry up the slope. The wider track of the splitboard skis reduces sinking in soft powder snow.
“Free heel” ski bindings and adaptors, such as telemark, randonee or Alpine Trekkers, make ski touring easier. In addition, the skis may be adapted for climbing by applying climbing skins to the lower surface of the skis. The use of climbing bars propped under the boot heels aids in climbing steeper slopes and crampons may be used in icy conditions to decrease the risk of slipping. Free heel bindings, climbing skins, climbing bars and crampons are used by touring splitboarders as well.
In the occasional descent in ski touring mode, the heels of the boot bindings are optionally “locked down” to the skis, with descent using conventional alpine techniques, or more commonly left free with the toe attached by a pivot, with descent using telemark ski techniques.
The splitboard reveals its true utility on the downhill rides. The rider first joins the two skis of the split board pair to form a snowboard-like combination. The rider's stance in the snowboard riding configuration is sideways on the board, with legs spread for balance. Ideally, the rider descends the slope as if riding a snowboard, with heels and toes locked in place.
Some boards, known as “swallowtails”, are designed for deep powder snow. These boards have forked tails that allow the tail of the board to carve more deeply in the snow while keeping the nose of the board high.
Another version of splitboards, recently innovated in Europe, is formed with two narrow skis and a third fitted plank between the skis. When ski touring, the extra plank must be carried. It remains to be seen whether this will catch on in backcountry snowboarding elsewhere.
It should be noted that downhill skiing and snowboard riding require very different styles and skills. With skis, the body points in the same direction as the skis, and the skier uses hips and knees to change direction. Knee injuries are common because the legs move separately. On a snowboard, the body is essentially crossways on the board, and both heels are firmly attached to the board so that the feet, ankles, hips, and upper body can be used to set the board on an edge and make a turn. Knees are more protected because both legs are firmly secured to the board.
Backcountry splitboarding, which combines ski touring and snowboarding, thus requires boot bindings adaptable for both ski configuration (ie. one to a ski) and for snowboard configuration, (ie. joining the skis as a snowboard).
In one widely used configuration of the prior art, mounting block assemblies are attached in pairs crosswise on the opposing ski member halves of the splitboard, one pair for the forward leg and one pair for the back leg. These mounting blocks, disclosed in U.S. Pat. No. 5,984,324 to Wariakois (hereby incorporated in full by reference) include a toe mounting block and a heel mounting block, which are designed to slidingly receive an adaptor mounting plate (see the C-channel, item 74 of FIG. 6 of U.S. Pat. No. 5,984,324, also termed “slider plate”) and attached upper binding baseplate (item 72 of FIG. 6 of U.S. Pat. No. 5,984,324, also termed the “boot mounting assembly”), thereby conjoining the two ski members to form a snowboard. The mounting blocks, made of filled (fiber reinforced) nylon, are inherently compliant, and no means for dampening the compliance of the mounting blocks and associated stack of parts of the bindings is suggested. The adaptor mounting plate is also narrow relative to the width of the boot support plate as shown in FIG. 5 of U.S. Pat. No. 5,984,324. The narrowness of the C-channel saves weight, but reduces stability. Nonetheless, the adaptor mounting plate alone adds about 7 oz (or 200 g) of weight to each boot, and the total weight of an adaptor mounting plate with attached upper binding baseplate and bindings can be 1.5 kg or more per foot, dramatically increasing the rider's burden. A rear stop tab on the adaptor mounting plate prevents the plates from sliding forward over the heel mounting block and a clevis pin is used to lock the toe of the adaptor mounting plate on the toe mounting block.
This same clevis pin is used as a pivot pin when the adaptor mounting plate is relocated to a ski mounting bracket. But experience has shown that the forces on the pivot pin are such that the pivot pin cradle and adaptor mounting plate of the prior art rapidly fatigue and are ovally deformed, leading to heel “fishtailing” in free heel mode, which destabilizes the rider and which must be repaired by replacement of the worn parts.
A second system for grippingly conjoining the ski member halves of a splitboard is disclosed in U.S. Pat. No. 6,523,851 to Maravetz, hereby incorporated in full by reference. This system employs a recessed ring with raised flanges that mate with a clamshell adaptor plate to secure the upper boot assembly to the board. The preset angle of the foot relative to the board can be changed by use of a locking pin in the rotatable lower half of the lower adaptor plate. The clamshell is hinged at the toe, but conversion from touring mode to snowboard mode can be difficult with this system because snow often gets inside the clamshell works during touring, and consequently this system has proved less than satisfactory in field experience by snowboard riders.
Both of the above prior art splitboard systems employ stacked mechanical members, including interposed adaptors, to secure the boot bindings to the board interchangeably between ski and snowboard configurations. In addition to the ski member conjoining function, these approaches teach the utility of a universal mounting system and upper binding baseplate for the industry-standard (3- or 4-hole) disk used in most strap-type or step-in snowboard and ski boot mounting systems, including for hard, hybrid, or soft boots. An even more complex example of an adaptor plate is shown in US 20040070176 to Miller. These teachings point to the continued need for improvement in this field.
Splitboarding is no longer a crossover sport. The majority of board riders have developed a preference for soft boots, which many find to be lighter, more comfortable, and better adapted to the style of riding they prefer. Only a minority of riders use hard boots. Board riders typically require a greater range of motion at the ankle than hard boots provide. Flexibility at the ankle (also known as “foot roll”) enhances the rider's ability to shift his or her weight and body position around the board for balance and control by allowing for a wider range of angles the legs can make with the board. For example in riding over a mogul, the rider shifts weight to the back of the board as the angle of the slope changes, or in carving a turn in hard snow, the rider will lean forward on the board. Flexibility may also improve the overall ride by allowing bumps to be more readily absorbed by the ankles and knees. Thus, the freedom of the foot to “roll”, and allow the angle of the leg to change relative to the board provides a performance and feel that many riders find desirable. Soft boots have emerged as a clear preference among splitboarders.
Boot bindings for use with soft boots are of two basic types: “strap bindings” and “step-in bindings”. A strap binding, which has been the traditional type of binding for a soft boot, includes one or more straps that are tightened across various portions of the boot, securing the boot in a boot pocket formed by the binding upper. For example, an ankle strap may be provided to hold down a rider's heel in the heel cup and a toe strap may be provided to hold the front portion of the rider's foot.
Step-in snowboard bindings, both toe-and-heel and sole side-grip bindings, have been developed for use with soft snowboard boots. Most of these require specially fabricated boots matched to the bindings. “Bails” may be used at the heel or toe to secure the boots, as with mountaineering boots. Newer innovations include highbacks with click locking mechanisms.
However, while innovation continues, the prior art has not produced a boot binding optimized for splitboarding. Components of the prior art—including 4-hole disk bindings, adaptor mounting plates, slider tracks, rubber gaskets, and filled-nylon upper binding baseplates, for example—increase overall wobble experienced by the rider (due to additive stacked tolerances and compliances), add weight, and put more height between the rider's heel and the board itself: all undesirable characteristics. The lack of firm broad contact between the most commonly sold adaptor mounting plate and the board surface also adds to the rider's instability.
The added “flex” or “play” in the mechanics of the prior art adaptor mounting plates, and associated mechanical stack members, which float above the surface of the board (see Example 2), results paradoxically in dampening of the rider's movements with respect to the board and loss of control. The apparent paradox arises because although freedom of movement of the ankle in the boot binding is essential to good riding, there must also be torsional stiffness—the rider's motions must be resisted by an optimal level of stiffness in the binding so that the legs cannot simply flop back and forth, but rather the binding resists this torsional motion (in the engineering sense) with a spring-like stiffness, allowing the rider to apply pressure at the desired segment along the length of the board.
The board is controlled by the bite of its edges in the snow. The rider steers by relocating pressure from one side of the board to the other as well as from nose to tail. Toeside and heelside turns on a snowboard involve a complex combination of dorsiflexion and plantar flexion, plus the roll of the calcaneus, talus, and subtalar joint, nosewise and tailwise on the board. While these motions would seem to be favored by a completely loose binding, in fact, an optimal torsional binding stiffness is required. Torsional stiffness is the spring force in the bindings that opposes the rider's motion. This opposing force translates the rider's motion into pressure on the desired section of the board. When the rider bends downslope, for example, the boot bindings transmit pressure onto the nose of the board. When the rider bends upslope, the boot bindings transmit pressure onto the tail of the board. Similar forces come into play as the rider leans toeside or heelside. If the bindings lack torsional stiffness, the ability to apply control pressure to the intended segment of the board is decreased. Torsional looseness is felt as “play”, “slop” and instability. Conversely, if the bindings are too stiff, the legs cannot pivot, and the rider loses balance and control. Therefore, there is an optimal stiffness, providing an optimal mix of freedom of motion and board control.
While hard ski boot bindings are too stiff to allow the range of motion most snowboarders prefer, the splitboard systems of the prior art incorporate a soft boot binding with an adaptor mounting plate that is not stiff enough and has excess play. Although the rider can readily bend at the ankle, the lack of stiffness prevents the rider from precisely transmitting that force as a directed pressure at the desired segment of the board.
A problem first recognized and addressed by this invention is thus one of enhancing the torsional stiffness of snowboard boot bindings for use with splitboards in “snowboard riding mode”, and simultaneously improving performance and comfort of the equipment in free-heel “ski touring mode”. There is an unmet need for splitboard soft boot bindings with the stiffness, weight, and heel height for today's splitboard riding styles. This need necessitates a mechanical reinvention of the boot bindings from the board up.
Disclosed here are improved boot bindings for splitboarding. Contrary to the teachings presented herein, the teachings of the prior art disclose a boot binding with one or more adaptor mounting plates—so that boots and boot bindings designed for snowboarding can be adapted for crossover use with splitboards. This approach is problematic, adding weight, instability, and decreasing the torsional stiffness (or spring constant) of the boot bindings. No solution has been offered in the prior art that eliminates the weight and height of the essentially ubiquitous “adaptor mounting plate” and, as recognized herein, supplies the right amount of stiffness in the boot binding on the ankle to optimize rider control, while remaining comfortable and responsive for the soft boot rider. The lack of a prior art solution is not surprising because the problem has not previously been recognized in these terms.
Any solution to the problem must also allow the rider to easily reposition the boots when switching from snowboard riding to ski touring configuration, and the performance in ski touring configuration also must be improved.
The prior art adaptor mounting plate, which serves the function of adapting both snowboard-type soft-boot bindings and hard boot bindings to the snowboard mounting blocks and also to the ski touring mounting brackets of the prior art, can be advantageously eliminated. The adaptor mounting plate can be replaced with a box girder in which the top plate and “upper surface” of the box girder, on which the rider's boot is supported, and bottom plate with channel and inside flanges that grips the board, are joined by medial and lateral web spacer members having an aspect ratio different or modified from the aspect ratios of the top and bottom plate members. The aspect ratio of the web spacers may be varied from heel to toe, so that the box girder is shaped, proportioned and contoured to better support and secure the rider's boot. Stiffer torsional spring constants are obtained with the wider boot bindings of this construction, and interestingly, because of the integrated design, the overall height of the raised platform nonetheless places the rider in a position that is lower than possible with the devices of the prior art. While not being bound by theory, these teachings are a new solution to the problem of boot binding structural mechanics, and are shown here to have unexpected advantages that improve the splitboard ride.
The modified box girder serves dual functions in securing the boot on top and gripping the board with its lower aspect, while remaining itself structurally rigid. By limiting play and compliance between the girder and the board surface, the overall spring constant becomes relatively constant over the required flexural range, and approximates the spring constant of the boot itself, as modified by reinforcing structures such as boot pocket, upper side rails, heel cup, and highback, all of which increase stiffness adjustably.
By eliminating the adaptor mounting plate, and subsuming its functions as part of an integral boot binding lower, multiple improvements in form and function are achieved. Unneeded weight is eliminated. Reduction in heel height relative to the board surface results in a lower center of gravity on the board, for better balance and control. Recognizing the inherent plasticity of the mounting blocks, clearance spaces between the bottom surface of the box girder and the upper face of the board are reduced or eliminated, dramatically firming the spring constant for the bindings. Removal of the narrow adaptor mounting plate also increases the firmness of the foot and ankle contact with the board surface, and eliminates the looseness, flex, or “play” between the multiple mechanical components of the prior art that dampen the board's responsiveness to the rider's movements. This has proved an elegant solution to what was an unrecognized problem.
Happily, free heel ski performance is also improved. For one, by replacing the pivot pin used with the prior art adaptor mounting plate with a longer pivot pin mounted through the thick webs or spacers of the structural girder at the toe of the integral boot binding lower, wear on the parts is dramatically reduced. In the embodiment of Example 1, the pivot pin is lubricated and reinforced by ultrahigh molecular weight polyethylene (UHMWPE) used as a spacer material in the toe of the integral boot binding lower. This eliminates oval mounting-hole deformation characteristic of prior art pivot pin mounting cradles. Again, broader and more firm toe contact with the board is obtained, improving performance in free heel skiing. Snow, which invariably can pack up under the boots and mounting blocks during skiing and snowboarding, is vented out under the heel, easing the switch from ski touring to snowboard riding configuration, and vice versa.
The use of variform box girder construction, where the web aspect ratio is varied independently of the aspect ratios of the top and bottom plate members of the girder, permits shaping, proportioning and contouring the top surface of the binding to the sole of the rider's boot, while preserving the fixed dimensions of the channel and inside flanges of the bottom plate. As demonstrated here, control of the board is improved by eliminating cumulative elastic and inelastic deformation that is readily observable in boot bindings of the prior art (see Examples 2 and 4). The binding is configured so that bottom medial and lateral flanges touch down on the board face during maneuvers. Comparative field studies performed with embodiments of this invention show that torsional stiffness is increased to a efficacious level, resulting in improved control and comfort for the splitboard rider.
The teachings of the invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings and claims, in which:
Certain meanings are defined here as intended by the inventor, i.e., they are intrinsic meanings. Other words and phrases used here take their meaning as consistent with usage as would be apparent to one skilled in the relevant arts. When cited works are incorporated by reference, any meaning or definition of a word in the reference that conflicts with or narrows the meaning as used here shall be considered idiosyncratic to said reference and shall not supersede the meaning of the word as used in the disclosure herein.
Board: a low-friction, generally elongate and generally planar surface intended for supporting a standing person while sliding over snow or ice; typically a “splitboard” as used here.
Splitboard: a combination consisting of two separable ski members, each generally having one nonlinear longitudinal edge, that can be joined at opposing lateral edges to form a snowboard. The ski members are typically shaped so as to approximate the right and left halves of a snowboard respectively. The tips of the ski members are generally secured together in the snowboard configuration by use of hooks and pins, or other conjoining apparatus, but the relative stiffness of the coupling is largely the result of the mechanics of the transverse union formed by the boot bindings and associated hardware straddling the separate ski members.
Boots: are of three general types, i.e., hard boots, soft boots and hybrid boots (for example “plastic mountaineering boots” which combine various attributes of both hard and soft boots). Hard boots are exemplified by alpine and telemark ski boots and typically employ a moderately stiff or very stiff molded plastic shell for encasing a rider's foot and lower leg with minimal foot movement allowed by the boot. Hard boots and mountaineering boots conventionally are secured to the board using plate bindings that include front and rear bails or clips that engage the toe and heel portions of the boot.
Soft boots, as the name suggests, typically are comprised of softer materials that are more flexible than the plastic shell of a hard boot. Soft boots are generally more comfortable and easier to walk in than hard boots, and are generally favored by riders that engage in recreational, “freestyle” or trick-oriented snowboarding, or alpine riding involving both carving and jumping. Soft boots are conventionally secured to the board with either a strap binding, a step-in binding with lateral clamp (such as US Patent Application 20020089150), or with the flow-in bindings, clickers, or cinches of hybrid bindings known in the art (such as U.S. Pat. No. 5,918,897 to Hansen and U.S. Pat. No. 6,173,510 to Zanco).
“Ride” or riding: a noun or verb used by snowboarders to indicate the distinctive downhill slide experienced by a rider on a snowboard (or on a splitboard in snowboard mode). Snowboarders ride; skiers ski.
Ski tour or touring: When used as a noun, indicates: a trip through areas typically away from ski resorts, referred to as the backcountry, which may include traversing flat areas, ascending inclined slopes and descending slopes using one or several of the following pieces of equipment: skis, poles, snowshoes, snowboards, or splitboards. When used as a verb, indicates: to enter the backcountry, typically away from a ski resort, and perform one or more of the following: traverse flat areas, ascend inclined slopes, and descend slopes using one or more of the following pieces of equipment: skis, poles, snowshoes, snowboards, or splitboards.
Ski touring configuration or mode: indicates a configuration in which the two ski members are separate and are attached one to a leg, typically with a free heel binding to facilitate traversing terrain and ascending slopes. When used to describe a splitboard configuration, indicates that the ski halves have been separated and the rider is ski touring on the separate ski members attached to each foot.
Ski mounting assembly: refers to hardware, brackets, pins or blocks secured on the surface of each ski, generally centrally placed, so that boot bindings can be fastened to them, one boot to a ski, in the ski touring mode or position. In the most common conventional device, a ski touring pin cradle is used with a pivot pin or pins with the pivot axis extending through the toe of an adaptor mounting plate, the purpose of which is to provide a hinged coupling between the boot and its counterpart ski member, as in telemark skiing and “free heel” skiing. A ski mounting block may take the place of the pin cradle and may be used with boot mounting tongues, cables, or other pivoting means. Bushings may be used to extend the life of the wearing surfaces. Incorporated herein by reference with respect to pivoting means are U.S. Pat. No. 5,649,722 to Champlin, U.S. Pat. No. 6,685,213 to Hauglin, U.S. Pat. No. 5,741,023 to Schiele, US Pat. Appl. 20050115116 to Pedersen, and their cited references. As described herein, a webbed girder construction of the boot binding beam permits use of a longer pivot pin with less wear.
Snowboard riding configuration or mode: indicates a configuration in which the right and left ski members are joined at opposing lateral edges to form a snowboard and the rider mounts the board with both feet spaced and secured in the mounting block assemblies.
Snowboard mounting block assembly or “mounting block assembly”: refers to a pair of flanged mounting block elements (also termed “slider blocks” in the prior art or simply “mounting blocks” here) secured to the ski members of a splitboard so that they can be conjoinedly and flangedly interlocked in the snowboard configuration. For example, the mounting block assemblies (17,18,19,20,21—
Variform box girder: is a rigid girder formed as a box with top plate member with an “upper” or “top” surface (for supporting the sole of the rider's boot), a bottom plate member with bottom surface and bottom mediolateral flanges, and with lateral and medial webs for structural rigidity. Also included is a bottom channel with parallel interior flanges formed in the bottom plate for attaching the boot binding to a mounting block assembly on a splitboard. A variform box girder is further characterized as having a shape which varies from toe to heel so as be proportioned and contoured for fitting and contactingly supporting the sole of a rider's boot, and is widened at the bottom flanges, relative to the mounting blocks, for better distributing torsional forces onto the face of the splitboard. The web members of the variform box girder typically have a variable aspect ratio that is modified and different from the aspect ratio of the plate members; i.e., the aspect ratio of the web members may be varied independently of the aspect ratio of the plate members. A variform box girder may be formed as a modified sandwich box girder or as a modified monolithic box girder.
While the top and bottom plates of a box girder are conventionally termed “flanges”, the word flange is reserved here for a) inside flanged edges formed facing a box-ended channel between the webs on the bottom of the box girder and b) mediolateral flanges of the bottom plate. The modified box girder may be monolithic, that is “fabricated as a single piece”, or fabricated by forming or fusing of the basic girder elements (top plate, bottom plate, lateral web, and medial web) into a single structural and functional unit.
Sandwich box girder: is a rigid girder formed as a box with top plate member with upper surface (for supporting the sole of the rider's boot), bottom plate member with bottom surface, lateral web and medial web. Sandwich box girders have three layers, but two of the layers may be consolidated, for example by web elements consolidated as projections of the top plate. Bottom plate members may be single-piece or two-piece, as for example where a separate flange member is joined to the base of each of the web members in the manner of a “pi-girder”. Sandwich box girder includes two-piece, three-piece and four-piece compositions. Similarly, web members may be assembled as a single piece or subassembly with right and left aspects, or as two pieces or subassemblies with right and left members of a pair. The modified sandwich box girder may be formed with webs or plates having an aspect ratio or contour height that varies from heel to toe. Furthermore, the material properties of the spacer members may differ from the material properties of the plate members in a modified sandwich box girder. In a preferred embodiment of a sandwich box girder, the spacer members are honeycombed to reduce weight.
Web: is a generally vertical element of a girder for joining a top plate or surface and a bottom plate or surface of the girder. A typical box girder has two webs, a medial web and a lateral web, although double box girders are also conceived. The webs may be side webs or recessed webs. Web elements resist both compressive and tensile loads, including torque and bending when a load is applied to a box girder. The aspect ratio of the web element is varied independently of the aspect ratio of the top plate member or the bottom plate member.
Integral boot binding lower: refers to a modified box girder constructed with a top plate forming a raised platform surface and a bottom plate with lower aspect for engaging a snowboard mounting block assembly of a splitboard in snowboard riding configuration. Girder webs joins the top plate and bottom plate (where the webs are either made of a structural spacer material, “honeycomb” or “core”, laminated, molded, glued, solvent-welded, or otherwise affixed between the top and bottom plates—or are an integral part of the material of the top or bottom plate, as by molding, extrusion, sheet folding, welding, solvent welding, riveting, thermal fusion, casting or machining). In other words, the modified girder may be a monolithic single piece, or may be a sandwich construct: including three-layer sandwich constructions having individual top plate, bottom plate, and conjoining webs, and two-layer sandwich constructions, which include top plate with integral webs joined to bottom plate, and bottom plate with integral webs joined to top plate. One or both web members may be split by a channel along their length to reduce weight. In a preferred embodiment, each web member includes an internal web running the length of the binding from toe to heel, and an external wall (i.e., either laterally or medially placed relative to the internal wall). The internal web functions for supporting the internal flanges and the external wall is present only at the toe end, where the binding width is greater. The webs are defined by width and height dimensions, where width is a lateral-to-medial dimension and height is a superior-to-inferior dimension, and may be contoured, being variably dimensioned in outline or profile, and may be tapered or untapered from heel to toe. The box girder is modified with a box-ended channel and inside flanges on the bottom surface, with transverse pivot hole at the toe end, optionally with endstop or crosspiece at the heel end, and with projections, top side rails, or perforations peripherally disposed for aiding in the attachment of straps or fasteners for securing the boot to the top surface. The ends of the girder are typically modified for heel and toe. Thus an integral boot binding lower is a modified box girder with adaptative modifications made for performing functions not performed by the elements separately. These functions include: a) supporting a boot on the top surface or aspect, with means for securing the boot to the boot binding; b) reversibly receiving and grippingly conjoining a snowboard mounting block assembly in snowboard riding mode; c) providing a means for pivoting at the toe in ski touring mode; d) serving as a rigid platform with bottom surface configured for contactingly engaging the top face of the splitboard when subjected in splitboard riding mode to bending stress by the rider; thereby providing an efficacious torsional stiffness. The box girder is defined by width and height dimensions, where width is a lateral-to-medial dimension and height is a superior-to-inferior dimension, and may be contoured, being variably dimensioned in outline or profile, and may be tapered or untapered from heel to toe. The width of the binding is generally greatest proximate to the toe pivot mount and is reduced posteriorly therefrom so that a least width is formed proximate to the heel. By “tapered width” is meant a dimension that diminishes or reduces toward one end such that the width is greatest proximate to the toe end and is reduced proximate to the heel end. The width need not be constantly or gradually tapered, but may instead be dimensioned and shaped to support the bootsole or to accommodate a slot for a toe strap, bilateral nose members for mounting a toe pivot pin, contralaterally disposed mounting posts or brackets for a heel cup, side rail mounts, and so forth, thus forming an irregular edge having an overall taper from a maximum width proximate to the toe and a minimum width proximate to the heel, where proximate indicates “in proximity to”. The height of the binding is also enabled to be variable, generally by varying the height of the webs, and may be greater at or near the toe or the heel to better support the bootsole and improve maneuverability, but may also be varied by dimensioning or bending the top plate as desired for use with a soft boot or hard boot. Similarly, an arch with toe and heel risers may be formed, for example, by varying the height of the top plate across and along its length.
Integral boot binding lowers are used in pairs (one for each foot), the rider places a first foot on one box girder anteriorly (front of center) and a second foot on a second box girder posteriorly (back of center) on the board surface in snowboard riding configuration. In the snowboard riding mode, the boot heels are generally secured to the board. However, provision is also made in the integral boot binding lower for the “free heel” ski touring mode by providing a toe pivot mechanism that engages the boot binding on the ski mounting assembly.
Integral boot binding lowers may be fabricated from metal, such as aluminum or aluminum alloys, titanium, or steel, and so forth, or from plastic or reinforced plastic, either molded, machined, cast, or extruded. In sandwich construction, the materials of the webs and one or both of the plates may be dissimilar. Spacer materials used for the webs include UHMWPE because of its toughness, resistance to wear, and lightness, but metals and plastics such as nylon, polypropylene, polycarbonates, polyesters, acrylates, polyimides, and polyamides or reinforced composites such as polyester fiber, carbon fiber, polyamide fiber, filled nylon, or aramid fiber thermosets may also be suitable. Some webs have truss elements. Webs may also be made of metal by forming arts such as casting, extruding, folding, pressing and machining operations and may include honeycombing, truss elements, or standoffs designed to reduce the weight of a solid web core.
In monolithic construction, the entire box girder with upper surface, bottom surface and bilateral webs is made of a single material, such as a plastic or a metal. In two-piece sandwich construction, where the web layer is formed as a consolidated projection of either the upper surface or bottom surface of the box girder, the materials of the top and bottom layers may be different. For example a top plate and web made of fiber-reinforced plastic and a bottom plate made of a metal may be sandwiched together, or vice versa, to form the box girder. A modified monolithic box girder may be formed with web/spacer members or plate members having an aspect ratio and/or contour height that varies from heel to toe. In a preferred embodiment of a monolithic box girder, the spacer members are honeycombed or machined to reduce weight.
“Upper boot binding” or “boot binding uppers”, generally refers to optional elements of a boot binding attached to an integral boot binding lower with fasteners, but may include elements that are molded or otherwise formed in place, and generally includes shaped supports that contact and secure the boot, for example a highback which may be foldable, a heel cup, side rails, and one or more straps, most commonly a heel strap and a toe strap, while not limited thereto. Bails may also be used. The uppers may also include a toe riser formed to the boot, shell, cushioning, and components that are engaged when the boot is inserted. These elements are generally formed of assemblies separable and distinct from the integral boot binding lower, for example aluminum, titanium, and steel (used in hardware, ratchets, heelcups, cables, baseplates, highbacks, etc), neoprene rubber, silicon rubber, low density polyethylene, polypropylene, fiberglass, nylon, filled nylon, leather, fabrics, stitching, EVA foam padded cores, and the like, with associated hardware for fastening. The boot binding uppers provide adjustable stiffness to the boot binding when attached to a rigid integral boot binding lower and thus contribute to the torsional stiffness of the boot binding as a whole. Selected upper elements are typically adjustable, for example the heel cup, allowing fitting for boot size and personal adjustment within the underlying limits of the design. The boot binding uppers are not the upper binding baseplate or “tray” of the prior art (compare elements 7, 60, 61 and 62 of
Optionally, several sizes of boot binding lowers are made available for riders of various size or age, and these are further personalized by the selection of elements of the boot binding uppers. All boot binding lowers have identical bottom plate channel dimensions.
Receiving and grippedly conjoining: refers here to the action of slidingly and reversibly engaging a mounting block assembly or “slider track” with the adaptor mounting plate of the prior art or by a box girder with box-ended channel and internal flanges so as to conjoin two ski members in snowboard riding configuration. In the inventive device of Example 1, for example, the box-ended channel formed in the box girder of the integral boot binding lower flangedly interlocks with flanged surfaces of the mounting block assembly. In a preferred embodiment, the box end of the box-ended channel prevents the integral boot binding lower from slipping over the mounting block elements from the heel. A transverse pin or other locking means may be used to secure the boot bindings at the open end of the box-ended channel at the toe. When this locking means is opened, the boot bindings may be slidingly removed from the mounting block assembly.
Adaptor mounting plate: refers to an intermediate mechanical device of the prior art for securing a 3- or 4-hole disk-mounted boot binding to the snowboard mounting blocks and ski touring tabs on a ski, snowboard, or splitboard. In its preferred configuration, the adaptor mounting plate, or “slider plate”, consists of an anodized C-channel press folded from an aluminum alloy plate. In the prior art, the adaptor mounting plate (
Four-hole disk: a component of a conventional snowboard binding that mechanically couples the body of the tray to the board. The four-hole disc is circular and can be rotatingly coupled to the binding, thus allowing the rider to select an angle of placement for each foot with respect the longitudinal axis of the board. Three-hole disks have also been used.
Highback: An element that extends from the heel up the calf in part, and serves as an ankle brace to control the heel and leaning on turns, and can be rigid, semirigid, or flexible. The highback can also used to secure the boot into the boot binding upper in some step-in boot bindings. Highbacks typically have a pivot that allows them to be laid flat, decreasing the amount of storage space needed for the boot bindings.
Aspect Ratio: defined conventionally as unit height (or thickness) per unit width (or length). The aspect ratio of a top or bottom plate member may be generally constant and the aspect ratio of a web member may be generally variable over the length or width of the binding, as results in contouring and tapering of the variform box girder. The aspect ratio of the web members may be modified or selected to be different from the aspect ratio of the plates as required. In some instances, the aspect ratio of the web member is a constant, in other instances the aspect ratio is variable, but the aspect ratios of the web members and the plate members are not uniform or equal because the dimensions of the web members are selected to serve functions distinct from those of the plates. For example, the aspect ratio of the web member may be varied to permit a tapered width of the binding (while maintaining a constant bottom channel width), whereas the plate members may have a thinner, more uniform aspect ratio. The aspect ratio of the web members may be varied independently of the aspect ratio of the plate members.
Material properties: refers to properties of materials that vary from material to material, for example hardness, density, modulus of elasticity, tensile strength, wear properties, fatigue resistance properties, and so forth. Material properties may be uniform from member to member, as in a monolithic article cut from a single block or an article folded from a single sheet, or may be different. The material properties of aluminum, for example are different from the properties of UHMWPE, or filled plastic, or steel, for example. Substituting one material for another results in a member having different material properties.
Torsional stiffness: in its simplest engineering analysis, torsional stiffness can be approximated by a form of Hooke's law relating torque to deformation:
T=K*Δθ (Equation 1)
where T is torque, K is a spring constant reflecting the stiffness, and Δθ (theta) is the angular deformation or displacement relative to the heel pivot. A more complex model including elastic shear modulus, loss shear modulus, and dampening coefficients may also be formulated. Considering only the box girder, a preferred level of torsional stiffness is in the range of 150 to 300 in-lb/degree when taken as rotation of the box girder mounted on a pair of mounting blocks to a splitboard. A corresponding preferred level of torsional stiffness taken for the binding interface as a whole (ie. with boot and boot binding upper) is in the range of about 50 to 150 in-lb/degree, most preferably in the range of 70-130 in-lb/degree. The composite stiffness of the boot with boot binding upper is typically less than the stiffness of the box girder so as to permit a greater range of ankle motion. An increase or decrease in torsional stiffness of 50% is highly significant and is readily perceptible to a rider.
Foot roll: is a term used in the art to denote the freedom of angular leg movement experienced by a board rider. The rider uses foot roll to shift the pressure or “bite” of the board on the underlying snow and to control the ride. Foot roll is essentially the “Δθ” in the equation for torsional stiffness. Optimizing the stiffness factor K, optimizes the control of the ride achieved with foot roll.
“About” and “generally” are broadening expressions of inexactitude, describing a condition of being “more or less”, “approximately”, or “almost” in the sense of “just about”, where variation would be insignificant, obvious, or of equivalent utility or function, and further indicating the existence of obvious minor exceptions to a norm, rule or limit. “Essentially” indicates a condition of close approximation to a limiting condition, wherein any departure from that limit is not significant.
Herein, where a “means for a function” is described, it should be understood that the scope of the invention is not limited to the mode or modes illustrated in the drawings alone, but also encompasses all means for performing the function that are described in this specification. A “prior art means” encompasses all means for performing the function as are known to one skilled in the art at the time of filing, including the cumulative knowledge in the art cited herein by reference to a few examples.
Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to”.
Referring now to
The top plate and bottom plate shown in this illustration are made of sheet metal as described in Example 1, but may also be made of reinforced plastic composites, either as molded or extruded sheets, or may be machined from metal stock. As shown in this embodiment, folded tabs of the top plate form side rails (6). An optional heel cup (7) may be fastened to the top plate rails. Provision for attachment of a toe strap (11), heel strap (12), and highback (13) are also illustrated. A single hole may be used for both the highback and heel strap.
In this embodiment, the spacer or core web material of the girder is a lightweight material, but carries both compression, tensile, and bearing loads. The aspect ratio of the web elements is varied from heel to toe. The material is characteristically tough and can be machined, drilled or molded. Honeycomb or truss webs are also contemplated. As will be described below, box girders with non-sandwich construction having integral or monolithic web elements may also be used.
Box-ended channel (9) and bottom plate parallel internal flanges (10) form a gripping means that joins the box girder to mated snowboard mounting blocks inserted in the box-ended channel. Structural elements of this embodiment include a means for pivoting the structure at the toe, here indicated by a transverse axial hole (14) for insertion of a toe pivot pin for pivoting as described in
The integral boot binding lower provides rigidity in joining the two ski members, but also must provide a rigid platform for the boot bindings that secure the boot to the board. Without adequate stiffness in the integral boot binding lower, the torsional stiffness of the upper boot bindings will be correspondingly insufficient.
Note that in the prototype of Example 1, the prior art adaptor mounting plate of
The bottom plate (5) of
By interlocking the boot binding flanges (10) and the mating external flanges (22) on the mounting blocks (18, 19), the two ski members (15, 16) are rigidly conjoined. The boot bindings and flanges of the box channel are provided with mechanical clearances so that the boot binding reversibly may be inserted onto the mounting block assembly. A toe locking pin (23) inserted at (14) prevents the assembly from slipping and is held in place with snaps (24). Thus in snowboard riding configuration, the sandwich box girder (1) traverses or “straddles” the pair of skis, and flangedly interlocks them in the form of a snowboard, also fixing the boot heel in place. Optional heel cup 7 is shown here for clarity.
A pair of internal pucks (20, 21) are supplied with fasteners for securing the pair of snowboard mounting blocks (18, 19) to the pair of ski members (15, 16), and permit adjustment and alignment for individual fit. The snowboard mounting block assembly (17) is adjusted to the preferred stance or angular orientation of the user and, in one embodiment, may be set up for the position of the user's feet in either a left-foot-forward or a right-foot-forward mode.
Also adding to the truss character are the upward-folding side rails (6) of the top plate member. The top plate may also be used to make provision for attachment of elements of the boot binding upper with fasteners. Provision for attaching a toe strap is provided at 11, and for a heel cup at 28 on the optional top plate side tabs or rails (6).
For comparison, a prior art design is shown in the accompanying panel,
Comparing
The soft boot binding upper baseplate (32), side rail (35) and an optional heel cup (46) can also be seen in this view. The heel riser (34) partially obscures the toe riser (33), which is higher for the left big toe. Boot bindings optionally may be designed to accept only a left or right foot, or may be interchangeable.
Note the height of the baseplate (32) above the upper board surface (15) and compare with
Also shown in
The adjustment of the pucks to position and align the mounting block elements is provided for by screws in slots 48 and 49 of the sectional view (not shown: the screws mate with threaded inserts embedded in the ski members).
Also shown are the hardware assemblies used in ski touring mode, which are more centrally placed on the ski members. Item 51 is a ski toe pivot assembly; item 52 a ski heel rest and climbing bar assembly. These two assemblies form the ski mounting assembly (50), which is used in ski touring configuration, as will be discussed next. The user may readily remove the boot bindings from the snowboard boot mounting block assemblies and reattach them to the ski mounting assembly. The binding assemblies of the invention permit rapid tool-free conversion from the ski mode to the snowboard mode, or vice versa.
The functional mechanism is revealed in more detail in the lower panel (
In
In
At the heel (26), climbing pin assembly (52) consists of a heel rest pad (56) and climbing bar (55). In
In
As first disclosed in U.S. Provisional Patent Application 60/792,231 (filed 14 Apr. 2006, this filing having priority thereto, and incorporated herein in full by reference),
Injection molding a unitary boot binding lower offers full integration of the dual functions of the rigid box girder with upper surface modifications for supporting and securing the rider's boot and lower surface modifications for gripping and conjoining the mounting blocks on the splitboard halves. With fiber-reinforced materials, for example nylons, significant weight savings is possible without sacrifice in strength. Wider, webbed beam/girder designs with reduced or zero freespace between girder and board upper surface reduce narrowly focused loads on the plastic external flanges of the mounting blocks, and on the collars of the ski pivot pin, thus realizing the first practical designs of splitboard boot bindings for injection molding. A molded plastic integral boot binding lower weighing less than 500 grams, more preferably less than 300 grams, is achieved.
As used herein, the terms “plastic” and “molded plastic material” include any thermoplastically processible resin. Examples of suitable thermoplastic resins include, but are not limited to, nylons such as 6,6-polyamide, 6,12-polyamide, 4,6-polyamide, 12,12-polyamide, 6,12-polyamide, and polyamides containing aromatic monomers, cyclic olefins, polybutylene terephthalate, polyethylene terephthalate, polyethylene napththalate, polybutylene napththalate, aromatic polyesters, liquid crystal polymers, polycyclohexane dimethylol terephthalate, copolyetheresters, polyphenylene sulfide, polyacylics, polypropylene, polyethylene, polyacetals, polymethylpentene, polyetherimides, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer, mixtures and graft copolymers of styrene and rubber, and glass reinforced or impact modified versions of such resins. Blends of these resins such as polyphenylene oxide and polyamide blends, and polycarbonate and polybutylene terephthalate, may also be used in this invention. The thermoplastic resins may also contain various types of reinforcements or fillers. Fiberglass or carbon fiber may be used for reinforcement of plastics. Various colored pigments may be added to the resin, such as titanium dioxide. Clays, calcium phosphate, calcium carbonate may be used as bulk fillers, and many other fillers such as talc and mica may be used to reinforce the material, to add strength or to modify other properties of the finished product such as stiffness. The resins may also contain plasticizers, and heat and light stabilizers. The amount of reinforcements or filler used may vary from about 1 to 70 weight percent based on the weight of the polymer and filler present. A preferred type reinforcement is fiberglass, and it is preferred that the fiberglass be present in the amount of about 15 to 55 weight percent based on the total weight of the polymer and filler present.
Composite constructs incorporating an insert in an injection molded part are also anticipated as a means of improving weight and strength of injection molded boot bindings, for example metal inserts or attachments forming the inside flanges of the boot binding beam lower aspect. These composites can be formed in the injection molding process or can be assembled separately with a molded subassembly. Similarly, lightweight foam cores embedded within plastic ribs can be used to decrease weight without sacrificing strength.
While the embodiment of
In
In
In the second of this series, turning now to
More generally, web constructs forming a box girder are shown schematically in
As shown schematically, the aspect ratio of the web elements is varied independently from the aspect ratio of the top and bottom plates. The aspect ratio of the two plates may also be varied independently. This results in a variform box girder which serves as a platform for a boot, where the shape, outline and contours of the top surface of the platform are optimized for supporting and securing the boot. The dimensions of the underside channel, however, are unchanged. Increasing the width allows the bottom plate flanges (at the mediolateral outside edges of the bottom plate) to contact the face of the board. As discussed with respect to
Conceptually, a representation of a variform box girder (300) for use as a boot binding lower is drawn in
Torsional looseness also arises from excess clearances. The clearance C1 between the bottom surface of the box girder and the top face of the splitboard (221), shown here in cross-section (
Similarly, any looseness in the play of the boot binding makes it difficult to recover from a sudden loss of balance, for example a rider who jumps and finds himself coming down on the tail of the board. In this case, the spring constant K in the boot bindings will help propel the rider back into an upright position relative to the board as the tail bottoms out. The feeling of being “tied in” to the board is lost if the boot binding stiffness is insufficient. Without sufficient stiffness in the boot binding, the board will seek its own level and the rider will be unable to regain balance. To solve this problem, excess torsional play in the coupling between the box girder and the board is eliminated and the rider is then free to select a preferred torsional stiffness in the boot binding uppers and by selection of soft boots with a desired composite stiffness coefficient.
Thus in another embodiment, the invention includes methods for controlling the ride of a splitboard by optimizing the torsional stiffness of the boot bindings. The torsional stiffness may be controlled dynamically by reversibly contacting either of the bottom lateral edges of the box girder with the board face. The steps of a method for controlling the ride may include a) mounting a boot binding of the present invention on a splitboard, where the splitboard is provided with paired mounting blocks for mounting the boot binding on the top face of the board, and the boot binding comprises a modified monolithic box girder or modified sandwich box girder having a top surface and top mediolateral edges configured for contactingly supporting and securing a rider's boot sole thereinbetween, and a bottom surface, the bottom surface having a pair of internal flanges forming a box-ended channel and a pair of bottom mediolateral edges, wherein the bottom surface and the top surface are joined as a single rigid member, and the bottom surface and box channel are configured with a clearance or clearances for slidingly engaging the paired mounting blocks; and b) while riding the splitboard, a step for reversibly contacting either one of the bottom lateral edges against the splitboard face by operatively applying a clockwise or counterclockwise torque through the boot sole, whereby the rider's boot sole and the board face are dynamically coupled by a single rigid member for the duration of the contact step. Preferably, the single rigid member has a lever arm L1 that extends from the fulcrum F* to the furthermost interlocking flanges of the mounting blocks. This single rigid member is the box girder and the lever arm for purposes of analyzing the torque is a radius drawn through the box girder from the fulcrum or pivot point at the bottom mediolateral edge contacting the board to the outside edge of the mounting blocks where deformation is maximal. This extended lever arm and single rigid member construction, in contrast to the short lever arm L2 and mechanical stack of
Also conceived is a method for promoting splitboarding, which may comprise a) supplying a pair of boot bindings to a rider, each boot binding of the pair comprising a modified monolithic box girder or a modified sandwich box girder having i) a top surface with top mediolateral edges, wherein the top surface is configured for contactingly supporting the rider's boot sole and the top mediolateral edges are configured for securing the rider's boot sole thereinbetween, ii) a bottom surface, the bottom surface having bottom mediolateral edges and parallel internal flanges forming a bottom channel and wherein the bottom surface and the bottom channel are configured with a clearance for receiving and grippingly conjoining a mounting block assembly affixed to a top face of a splitboard, and iii) a medial web spacer member and a lateral web spacer member for joining the top surface and the bottom surface as a single rigid member; and b) configuring the boot bindings to reversibly form a fulcrum F* contacting a first opposing edge of the bottom mediolateral edges to the top face of the splitboard in response to a clockwise torque applied by the rider and to reversibly form a fulcrum F* contacting a second opposing edge to the top face of the splitboard in response to a counterclockwise torque applied by the rider, thereby dynamically coupling the rider's boot sole and the top face of the splitboard via the single rigid member with a mechanical advantage when a torque is applied by the rider. While not limited thereto, a method for promoting splitboarding may further comprise one or more of the following steps: a) configuring the modified monolithic box girder or a modified sandwich box girder to rotate with a torsional stiffness coefficient K greater than 150 in-lb/degree when mounted on the mounting block assembly and K is measured with respect to rotation at the fulcrum; b) broadening the design of the bottom surface of the box girder so that the bottom mediolateral edges extend to or beyond the mediolateral edges of the rider's boot sole, i.e., so that the flanges (302a, 302b) of the bottom surface of the box girder are as broad or broader than the corresponding width of the rider's boot sole; c) adjusting in a design the clearance C1 or clearances between the bottom surface and the top face, optionally by inserting feet or shims; d) optionally providing a boot binding fitted to a size range of the rider's boot sole, or individually if desired as a custom-fitted box girder; or, e) providing at least one element of a boot binding upper attachable to the top surface of the modified monolithic box girder or the modified sandwich box girder, wherein the at least one element of the boot binding upper is configured for adjusting a composite torsional stiffness of each of the boot bindings.
In contrast, in the prior art boot binding of
In another embodiment, the invention is an improvement of a splitboard boot binding assembly, comprising a variform girder constructed with a top plate member with raised platform, a bottom plate member with lower aspect and bottom channel with parallel inside flanges for receiving and grippingly conjoining the boot bindings to a snowboard mounting block assembly affixed to a splitboard, and medial and lateral webs formed as spacer members between the top and bottom plate members. The bottom flanges are provided with mediolateral edges broader than the mediolateral edges of the sole of the rider's boot. The heel end optionally comprises an endstop or crosspiece and snow vent; and the toe end is provided with one or more means for pivoting at the toe in ski touring mode. The top plate member has medial and lateral edges and the medial and lateral edges are configured for securing the boot to the top platform, generally with detachable fasteners.
A boot binding of the present invention is further characterized in that the variform box girder is either a) fabricated as a single monolithic piece; b) formed of a first part or layer and a second part or layer, where the first part comprises the top plate member and the second part comprises the bottom plate member, and the lateral and medial webs elements are consolidated in the parts as projections of the top plate member or of the bottom plate member, and the top part and the bottom part are attached together with the spacer members therebetween; or c) formed as three layers or parts, the first layer including top plate member, the third layer including the bottom plate member, and the second layer including the web “spacers” joining the top and bottom plate members.
In sandwich construction, the box girder may be fabricated from multiple pieces selected from top plate, bottom plate, lateral web, medial web, or combinations of top plate with projecting webs, bottom plates with projecting webs, and lateral web with medial web (the lateral web may be joined to the medial web for example by a crosspiece) and assembled as a sandwich using fasteners, adhesives, rivets, spot welds, or other joining technique such as ultrasonic welding. Similarly, the bottom plate may consist of a medial plate or flange and a lateral plate or flange. The bottom plates may be joined at the heel by a crosspiece.
For monolithic construction, the box girder is fabricated from a single piece, either by molding, casting, machining, or a combination thereof, typically from a metal or a plastic.
The web elements are either made of a structural “spacer” material, including “honeycomb”, “truss”, “standoff”, or “core” elements, and is laminated, molded, glued, solvent welded, or otherwise affixed between the top plate member and bottom plate member—or made as a consolidated part of the material of the top plate or bottom plate, as by injection molding, extrusion, welding, solvent welding, thermal fusion, casting, or by machining from a single piece. The webs are formed with an aspect ratio that is independently varied from the top and bottom plates, and optionally from heel to toe. The resulting variform girder more fully supports and secures a rider's boot to an upper surface of the boot binding. Optionally, the web materials are selected independently from the materials used to form the top or bottom plate members. Both sandwich and monolithic construction result in fitted boot bindings having an integral bottom channel with parallel inside flanges for gripping and conjoining the mounting blocks of a splitboard. The bottom plate comprises parallel inside flanges formed around a channel between the medial and lateral webs; the channel is optionally box-ended. Using complex structural webs as described, the boot-supporting surface may be contoured, shaped, and widened while preserving the dimensions, planarity, and parallel flanged edges of the underside channel. This results in a variform box girder which serves to join the halves of a splitboard and as a platform for a boot, where the shape, outline and contours of the top surface of the platform are optimized for supporting and securing the boot.
The toe end 401a is modified by medial and lateral nose elements (410) for mounting the toe pivot pin and medial and lateral slots (412) for mounting the toe straps. A side channel 420 is formed in the medial and lateral webs as shown schematically in
This view also illustrates the clip-lock feature of the toe strap 403, which is fitted with a stub pin 431 that may be inserted into slot 412 formed on the outside edges on the top plate bordering the position occupied by the ball of the foot, and which may snap into one of two positions to ensure a snug fit over the boot. The toe pivot pin 402 is secured between the toe strap 403 and the riders boot.
The self-locking toe pivot pin is useful in both ski touring and snowboard riding modes. The toe pivot pin secures the boot binding onto the toe pivot cradle and also serves to lock the boot binding onto the snowboard mounting block assemblies in snowboard riding mode. Advantageously, the self-locking feature eliminates the need for clevis pins on the pivot axle as shown in
Embodiments of
A Drake F-60 snowboard binding with integral heel cup and highback was modified in a shop by removing the upper binding baseplate (32) and 4-hole disk and substituting in their place a sheet of 2.5 mm aluminum with side rails folded up to form a shallow channel for the boot.
A three dimensional CAD design was sent to a local sheetmetal house that used a CNC (computer numerically controlled) laser cutter to cut the outline and holes for the aluminum parts necessary for the bindings. Sheetmetal press brakes were then used to bend the channels of the bindings. Similarly, a CNC milling machine cut out the UHMW polyethylene spacers from a sheet of 16 mm thick plastic. This machine provided all holes, the outline, and contoured surfaces.
Using mounting bolts, the heel and toe straps and highback were secured in place. A total of 10 screws, countersunk, were placed at the circumference of the base along each side of the sandwich to secure the plastic spacer materials (webs) in position between the aluminum plates.
A milled hole accommodates a longer pivot pin than used in the prior art, and a second smaller hole was placed in the aluminum side rails to secure a braided cable loop to protect against loss of the snap fasteners. Note that the inner dimensions of the channel formed by the plastic spacers is wide enough to snugly fit over the ski mounting tabs and that the transverse pivot axis lines up with the hole in the ski mounting bracket. UHMWPE lubricates the pin and spares wear on the pivot pin cradle mount.
Right and left boot bindings were made in this manner. To assemble the snowboard, the boot bindings are securely slid over the snowboard mounting blocks and locked in place with a transverse pin and snap fasteners. To switch to ski mode, the boot bindings are slipped off the snowboard mounting block assemblies and positioned at the toe over the ski mounting brackets so that the pivot pin can be aligned through the pivot holes and secured in place with snap fasteners.
Mechanical comparisons were made using a splitboard and boot binding assembly of the prior art versus that of Example 1. A Voile “Splitdecision 166” splitboard was used for the comparisons, and for the prior art testing, Drake F-60 snowboard bindings were mounted as recommended by the manufacturer on the Voile mounting hardware. The boot bindings were assembled in snowboard riding configuration for these comparisons.
Physical measurements of the two boot bindings were also made and are recorded in Table I.
To measure deformation under lateral strain, which is related to spring constant K of the boot bindings, the snowboard was clamped to a vertical surface so that the highback of the boot bindings were mounted parallel to the floor. An 11.3 kg weight was then clipped onto the top of the highback, and the angle of shear for the two assemblies was compared. Deformation under modest lateral loading was approximately 36% greater with the prior art boot binding, indicating an unacceptably low torsional stiffness. The degree of torsional stiffness in a boot binding is indicated by the degree of deformation under increasing lateral strain applied at the top of the boot. Ideally, the “spring constant” of the torsional stiffness relationship is relatively constant and linear through the required range of flexural deformation. “Torsional weakness” or “looseness” can result from excessive compliance in elastic parts, both with respect to materials selection and with respect to design, from excess tolerances when parts stack up, and from excess height of a parts stack.
The binding system of this example was noted to substantially increase lateral stiffness of the boot and to lower the center of gravity on the boot. In snowboarding tests undertaken during winter conditions on mountainous terrain, the increased lateral rigidity of the inventive bindings was found to result in immediately noticeable increases in control and responsiveness of the board in downhill ride mode.
Improvements were also noted in telemark and ski touring mode, which were attributed to the improved toe contact made by the boot with the board, particularly for kick turning, and the wider lever arm on the bracket.
Weight is reduced by 6 ounces (170 g) on each foot, a 15% weight savings. This weight savings noticeably decreases the effort required to ascend a slope because the weight on each foot must be repeatedly lifted and pushed forward. Each kilogram removed from the foot decreases energy expenditure 7% to 10%. Weight on the feet requires roughly four times the exertion to move as the same weight carried in a backpack. The weight savings is obtained by combining structures such as the upper binding baseplate (or “tray) and the adaptor mounting plate. This savings is also had by eliminating unnecessary structures like the four-hole disk (shown in
A torsional stiffness coefficient was measured for the boot binding of
As expected, torsional stiffness was not equivalent. The slope of the datapoints is the torsional stiffness spring constant K. A slope (502) of about 220 inch-pounds/degree was observed for the inventive article of
In the prior art article (see
A stiffer boot binding lower is achieved by the inventive box girders. The torsional stiffness of the overall boot binding is a combination of the K factor for the boot binding lower and corresponding K factors for the boot binding upper and the boot itself Thus a boot binding lower that lacks sufficient torsional stiffness undermines the stiffness of the boot binding as a whole.
Torsional deformation is a form of stored energy: i.e., the boot binding functions as a spring. During an elastic recovery phase, the rider is returned to an upright position. Thus the spring constant of the binding is directly perceptible by the rider as “too much”, “not enough”, or in “the right range”. The rider can adjust the spring constant by selecting a boot and boot binding uppers such as heel cup, riser, and ankle strap, but only within limits. However, when the upper baseplate 32, gasket 39, and four-hole disk 31 of the prior art are also included with the prior art binding, and K is again measured, K can quickly fall below 70 in-lb/degree. Compliance or “play” in this range is experienced as “wobbliness”. With typical setups currently available, K's of 32-70 in-lb/degree were measured—too low for good performance. Through a long process of trial and error, I have discovered that a preferred range of stiffness K (as a composite K, including boots, boot binding uppers, and boot binding lower) is in the range of 70 to 130 in-lbs/degree.
A block of UHMWPE, 25 mm thick by 100 mm by 75 mm, is trimmed to fit between the lateral and medial spacers of an integral boot binding lower of
While the above is a complete description of the presently preferred embodiments of the present invention, it is possible to use various alternatives, modifications and equivalents. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
This application is a Continuation-in-Part and claims the benefit under 35 U.S.C. §120 of U.S. patent application Ser. No. 12/483,152 filed on Jun. 11, 2009, now U.S. Pat. No. ______, which is a Continuation-in-Part and claims the benefit under 35 U.S.C. §120 of U.S. patent application Ser. No. 11/409,860 filed on Apr. 24, 2006, now U.S. Pat. No. 7,823,905, which claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 60/792,231 filed Apr. 14, 2006 and U.S. Provisional Patent Application No. 60/783,327 filed Mar. 17, 2006; all said priority documents are incorporated herein in entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60792231 | Apr 2006 | US | |
| 60783327 | Mar 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12483152 | Jun 2009 | US |
| Child | 13527358 | US | |
| Parent | 11409860 | Apr 2006 | US |
| Child | 12483152 | US |
