A ski is a long, flat device worn on the foot, usually attached through a boot, designed to help the wearer slide smoothly over snow. Originally intended as an aid to travel in snowy regions, they are now mainly used for recreational and sporting purposes. Also, a ski may denote a similar device used for other purposes than skiing, for example, for steering snowmobiles.
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The Nordic ski technology was adapted during the early twentieth century to enable skiers to turn at higher speeds. New ski and binding designs, coupled with the introduction of ski lifts and snowcats to carry skiers up mountains, enabled the development of alpine skis. Meanwhile advances in technology in the Nordic camp allowed for the development of special skis for skating and ski jumping.
Skis were originally wooden planks made from a single piece of wood. They are now usually made from a complex assembly of components including glass fibre, Kevlar, aluminum, other polymers, and composite materials such as carbon fiber, though many contain wood cores. Nearly all modern skis use a running base of high-molecular-weight polyethylene, and alpine skis use carbon-steel edges. These components are put together through a variety of ski manufacturing techniques.
Most skis are long and thin and curve upwards at the front to prevent digging into the snow. The skier is attached by bindings which latch ski boots to the skis. Beginning in the early 2000s, many ski manufacturers began designing skis and bindings together, creating an integrated binding system. These systems serve three purposes. Firstly, they often use a railroad track design, to allow the toe and heel pieces to slide, which in turn allows the ski to flex deeply, without a non-flexing spot underfoot due to the binding .Secondly, it gives the skier a better control on his skis, since the binding is not only screwed on the ski, but integrated in the ski core via inserts. Thirdly, it requires the consumer to purchase both skis and bindings from the same manufacturer due to the proprietary nature of the system, thus increasing sales.
Many types of skis exist, designed for different needs, of which the following are a selection.
Like all skis, the original alpine "downhill" skis were little more than wood planks. Early alpine skis, developed in Switzerland and Austria during the 1890s, were wider, shorter versions of the standard Huitfeldt Telemark model, meant to be more agile in steep terrain and in deeper snow. Rudolf Lettner of Salzburg began marketing steel edges in 1928, enabling the ski to grip on hard snow ice. The following year Guido Reuge introduced the Kandahar binding, providing for heel lock-down and improved control for downhill skiing. Downhill ski construction has evolved into much more sophisticated technologies. The use of composite materials, such as carbon-Kevlar, made skis stronger, lighter, and more durable.
By the late 1980s World Cup giant slalom skiers were getting race-stock skis with deeper sidecuts. In 1991, designers at Elan produced a very exaggerated version of this race ski, and in 1993 introduced a recreational version described by the company as offering a "parabolic" turn shape. This became the prototype of modern "shaped" skis (when viewed from above or below, the centre or "waist" is significantly narrower than the tip and tail). Virtually all modern skis are made with some degree of side cut. The more dramatic the difference between the widths of the tip, waist and tail, coupled with the length, stiffness and camber of the ski, the shorter the "natural" turning radius.
Skis used in downhill race events are longer, with a subtle side cut, built for speed and wide turns. Slalom skis—as well as many recreational skis—are shorter with a greater side cut to facilitate tighter, easier turns. Many ski manufacturers label their skis with the turning radius on the top. For a racing slalom ski, this can be as low as 12 metres and for Super-G they are normally at 33 metres. For off-piste skis the trend is towards wider skis that better float on top of powder snow.
The ski is turned by applying pressure, rotation and edge angle. When the ski is set at an angle the edge cuts into the snow, the ski will follow the arc and hence turn the skier; a practice known as carving a turn. While old fashioned "straight skis" which had little side cut could carve turns, great leg strength was required to generate the enormous pressure necessary to flex them into a curved shape, a shape called reverse camber. When a modern ski is tilted on to its edge, a gap is created between the ground and the middle of the ski (under the binding) as only the sides near the tip and the tail touch the snow. Then, as the skier gently applies pressure, the ski bends easily into reverse camber.
Influenced by snowboarding, during the 1990s the side cut became significantly more pronounced to make it easier for skiers to carve turns. Such skis were once termed carving skis, shaped skis, or parabolic skis to differentiate them from the more traditional straighter skis, but nearly all modern recreational skis are produced with a large degree of side cut.
Reverse Camber is a term that describes skis with something other than the traditional camber shape. Reverse camber skis have tips and tails that curve up while the length between them is flat. This allows the ski tip to remain above soft powder snow. The first production ski to feature reverse camber was the Volant Spatula which premiered in the 2002–2003 season. Since then, many manufacturers have experimented with the concept and today rocker and reverse camber can be found in dozens of ski models.
Twin-tip skis are skis with turned-up ends at both the front and rear. They make it easier to ski backwards, allowing reversed take-offs and landings when performing aerial maneuvers. The turned-up tail allows less application of aft pressure on the ski, causing it to release from a turn earlier than a non-twin-tip ski. Twin-tip skis are generally wider at the tip, tail, and underfoot and constructed of softer materials to cushion landings. Bindings are typically mounted closer to the centre of the ski to facilitate the balance of fore and aft pressure while skiing backwards or "switch", and built lower to the ski for easy rail sliding. Some skis are also manufactured with special materials or a different side cut design under and close to the foot to facilitate rail sliding.
In the past five years twin tips have become popular among youth skiers, ages 14–21. The popularity explosion of twin-tip skis created a push for the inclusion of more terrain park elements at ski areas. Once considered a passing fad, twin-tip skis have become a staple in the product line of all major ski-producing companies worldwide, with a few specializing in twin tips. Line Skis, started by Jason Levinthal, was the first company to market only twin-tip skis. The first twin-tip ski was the Olin Mark IV Comp introduced in 1974. The first company to successfully market a twin-tip ski was Salomon, with their Teneighty ski. While the first person to first introduce the Twin-tip to Salomon was famous Freeskier "Michael Douglas". These skis are used by freestylers also known as freeskiers.
The Alpine touring ski is a modified lightweight downhill ski with an alpine touring binding. Like the backcountry ski, it is designed for unbroken snow. For climbing steep slopes, skins (originally made of seal fur, but now made of synthetic materials) can be attached at the base of the ski. The heel of the ski boot can be clamped to the ski when skiing downhill and released when climbing. The type of ski is mainly used with alpine touring boots, which are rigid but lighter than downhill skiing boots, but may be fixed with a binding suitable for skiing in technical mountaineering boots.[1]
The monoski is wide enough to attach both boots to a single ski. After a brief boom in the 1980s, only a few thousand enthusiasts continue to use it. Due to its extra width and flotation in deep snow, enthusiasts claim it to be a superior powder ski. The monoski is produced by a half dozen companies worldwide in limited quantities.
The Telemark ski is a downhill or touring ski, where the binding attaches only at the toe. The Telemark ski was the first ski with a significant side cut, and evolved in the Telemark region of southern Norway early in the 19th century. It was popularized by Sondre Norheim of Morgedal in Telemark, when he demonstrated the ski and the Telemark style of skiing to the public at Christiana, Norway beginning in 1868. The fact that the foot is only attached to the ski at the toes means that flexible ski boots are worn. The primary turning technique involves pushing one foot forward and lifting the heel of the other foot.
Cross-country skis are very light and narrow, and usually have slight sidecut, though some newer skis are a sidecut more like an alpine ski. The boots attach to the bindings at the toes only. Three binding systems are popular: Rottefella's NNN, Salomon's SNS profil, and SNS pilot.
The ski bases are waxed to reduce friction during forward motion, and kick wax can also be applied for adhesion when walking uphill. Some waxless models may have patterns on the bottom to increase the friction when the ski slides backward.
The two major techniques are classical (traditional striding) and freestyle or skating, which was developed in the 1980s. Skating skis are shorter than classical skis and do not need grip wax. The skating technique is used in biathlons. V1 skating is done when going up a hill and one arm is the lead arm which poles ahead of the second with its side. V2 skating is done while going down a hill or on a flat area. It involves poling with every stride of the ski.
Skis for mountain/backcountry/cross-country free range skiing are designed for skiing on unbroken snow where an established track is lacking. These skis are characteristically 10 cm or more in width and often fitted with cable bindings to provide general sturdiness, and to make it easier to extract one's feet from deep snow banks, in case it should be impossible to reach the bindings by hand. This is also the model used by military forces trained to fight in winter conditions, and the most closely related to the original ski. The widest backcountry skis are often called Big Mountain skis.
These skis are specifically designed for moguls. They typically have a different flex pattern, are narrower and have a smaller sidecut than a common carving ski. The differences in the flex pattern of the ski are made to let the ski absorb the impact of the moguls with the tip, and to have a tail stiff enough to push on the last mogul, while not being as stiff as it won't bend on it.
Skis for ski jumping. Long and wide skis, with bindings attaching at the toe.
Most skis are mass-produced in large factories, with runs of 50,000 pairs of a specific model and size to achieve economies of scale. Since 2004 a few small companies have emerged in the United States dedicated to crafting custom-made skis, one pair at a time, each pair custom-designed for a specific customer. Best know of these shops are Wagner Custom (Telluride, Colorado), Igneous (Jackson, Wyoming) and Folsom (Boulder, Colorado). The custom-design process typically begins with a detailed questionnaire and interview, which the designer uses to determine the skier's needs. The designer can change flex, materials and ski shape to suit the skier's skills, weight and target snow and terrain. Core materials, structural components, base and edge materials can be of superior quality and durability. Customers often design their own topsheets.
Skis are sometimes used in place of tires on vehicles intended to travel over snow. The best known example of this is the snowmobile, but larger vehicles such as aerosans, snow coaches, and snow planes also employ skis.
As the water and mechanical sports, ski also was a subject of inspiration for the artists of the twentieth century.