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A ski binding is a device that connects a ski boot to the ski. Generally, it holds the boot firmly to allow the skier to maneuver the ski. However, if certain force limits are exceeded, it releases the boot to minimize skier injury, such as in the case of a fall or impact. There are different types of bindings for different types of skiing.
Modern alpine skiing bindings fix the boot at the toe and heel.
In some bindings, to reduce injury the boot can release in case of a fall. The boot is released by the binding if a certain amount of torque is applied, usually created by the weight of a falling skier. The torque required is adjustable, according to the weight, foot size, and skiing style. A snow brake prevents the ski from moving while it is not attached to a boot.
A alpine touring binding allows the skier to have the heel of the ski boot free and toe of the ski boot in the binding when using Nordic skiing techniques for ski touring and to have both the heel and the toe of the ski boot in the binding when using alpine skiing techniques to descend the mountain. Most touring bindings are designed for ski boots falling under one of two ISO specifications:
- ISO 5355:2005, for traditional alpine boots. In this variation the pivot is located in the front of the binding.
- ISO 9523:2008, for boots in which the pivot is formed at the boot / binding interface.
The two setups are mutually incompatible: in the former, the boot lacks sockets to engage ISO 9523 compatible bindings, while the later boot toe and heel-piece dimensions are incompatible with ISO 5355 bindings.
The cable binding was widely used through the middle of the 20th century. It has the toe section of the boot anchored, and an adjustable cable around the heel secures the boot. While binding designs vary, before 2007 almost all dedicated Telemark models had been designed to fit boots with 75mm Nordic Norm "duckbill" toes.
Rottefella (NN, Nordic Norm)
The Rottefella binding was developed in 1927 by Bror With. The name means "rat trap" in Norwegian. It is also known as the 75 mm, Nordic Norm, or 3-pin. After victories at the 1928 Winter Olympics in St. Moritz, the binding remained the standard for cross-country skiing for the next 60 years. They are no longer as popular as they were but are still for sale. The binding has three small pins that stick up from the ski. The toe of the boot has three holes that line up with the pins. The boot is then clamped down by a bail. The binding is asymmetrical, having left and right foot orientations.
NNN (New Nordic Norm) & NIS (Nordic Integrated System)
Rottefella's NNN (New Nordic Norm) has a bar in the toe of the boot hooked into a catch in the binding. There have been several versions of NNN, and the first NNN version is not compatible with current designs. It also exists in the more rugged BC (Back Country) version.
NIS (Nordic Integrated System), introduced in 2005 by Rossignol, Madshus, Rottefella, and Alpina is fully compatible with NNN boots and bindings, but is a different way of attaching the bindings to the ski. It features an integrated binding plate on the top of the ski to which the bindings attach, allowing adjustment in the field. NIS skis allow installation of non-NIS bindings. In 2007, Fischer abandoned SNS and entirely switched to NIS.
SNS (Salomon Nordic System)
SNS (Salomon Nordic System) looks very similar to NNN, except it has one large ridge and the bar is narrower. Three variants exist:
- Profil: the standard model (with one metal bar in the toe of the boot)
- Pilot: for either skate-style or classic-style cross-country skiing (with two metal bars on the boot)
- X-Adventure: for backcountry skiing.
NTN (New Telemark Norm)
In 2007 Rottefella introduced the New Telemark Norm binding. The system's objective is to provide a freeheel telemark ski binding featuring lateral release, increased lateral rigidity, tunable performance, and free-pivot touring functionality.
In the early days of skiing the binding was also similar to those of a snowshoe, a leather strap fastened over the toe of the boot. Timeline:
- 1840s: Sondre Norheim demonstrated Telemark skiing before 1866, and the Open Christiania in 1868, both made possible with a binding design (which dated back to the late 1840s). This added a loop of twisted birch roots that ran from the existing birch root toe loops around the boot heels and back. This allowed the heel to lift as before, for walking and gliding, but better held the boots to the skis allowing greater control. This enabled Sondre to control the skis with his feet and legs, replacing the former technique of dragging a large pole in the snow on one side or the other to drag the skier in that direction. These new techniques spread throughout Telemark and would later be named for the region.
- 1894: Fritz Huitfeldt invented a binding with a secure toe iron which allowed the heel to move freely. This became the standard industry binding through the 1930s. Fritz R. Huitfeldt drove the evolution of the ski binding over the next 20 years. In 1894 he introduced the use of semi-circular metal hooks at the toe to attach the straps. The hooks were positioned to tightly fit to the sides of the boot, keeping the ski centred and eliminating any "flop" that the formerly loose straps allowed. The heel strap was also attached to the same hooks, but because of their rounded shape, the required range of motion was provided by the straps sliding up and down on the hooks. This allowed the heel strap to be replaced by a less flexible leather strap. Together, these changes dramatically tightened the binding, greatly increasing control.
- 1897: Huitfeldt further improved the design by changing the toe piece. Instead of hooks, he drilled a rectangular hole through the ski from side to side, and passed an iron bar through it. The bar was then bent up on either side, locking it in place, and then formed to fit the toe of the boot. This improvement once again dramatically improved the firmness of the fit. Finally, in 1904 he adopted the Hoyer-Ellefsen toggle, a lever that replaced the buckles. This not only greatly improved mechanical advantage, further improving the strength of the binding, but also made the system much easier to put on and remove. Better yet, the geometry of the attachment points meant the heel strap was mechanically attached below that of the toe strap, which provided a constant "diagonal downpull" that naturally returned the heel to the ski.
- 1920: Huitfeldt style bindings were by far the most popular system for decades, with the only major change being Marius Eriksen's 1920 introduction of pre-formed plates that were screwed on top of the ski. Other binding systems did exist, in particular a class of bindings originally introduced by Mathias Zdarsky that replaced the heel strap with a long metal plate under the sole of the boot, hinged at the front to allow the heel to rise. The heel was held to the plate by a short strap attaching at the back. These gave even better control than the Huitfeldt design, but so firmly attached the leg that injury was a real problem.
- 1927: Change eventually came though the evolution of the Rottefella binding, first introduced in 1927. The original Rottefella eliminated the heel strap, which held the boot forward in the binding, by drilling small holes in the sole of the boot which fit into pins in the toe piece. This would only work if the sole was held very firmly down on the pins, so the binding also introduced a metal clip that was forced down onto the top of the sole of the boot, forcing it onto the pins. When the inventor, Bror With, won a race on the new design, Norwegian Crown Prince Olav ask him what they were, and he responded "Oh, they're just a couple of rat traps I picked up at the hardware store". "Rottefella" is Norwegian for "rat trap".
- 1929: The introduction of the cable binding allowed the Christie turn to become a standard on downhill runs, and to further support this style of skiing the Swiss racer Guido Reuge in 1929 invented a cable binding with steel clips below the boot heel to enable clamping the heel down for downhill portions. He named the product "Kandahar" for the international Kandahar Cup ski races. In use in alpine races, the Kandahar binding led to serious leg injuries, and by 1939 experimentation began in earnest on bindings that would release the boot in a fall.
- 1932: a major advance on the Huitfeldt concept was introduced to the market by Guido Reuge in 1932. Reuge replaced the heel strap with a metal cable connected to a spring at the front of the toe. The spring provided even tension as the boot moved. Previously, the strap was adjusted so it had enough slack to allow the boot to rotate as high as the skier wished, but as the boot rotated back down to the ski it became increasingly slack again. The cable removed this limitation, and held the boot firmly through its entire motion, greatly increasing the solidity of the fit. A later advance added two small metal clips near the rear of the foot that the cable could be clipped under. These held the boot firmly to the ski during downhill portions of the runs. Cable bindings remained in use for some time for cross-country, and are today popular for telemark skiing. However, the Rottefella design from the 1930s became more popular for cross country skiing through the 1950s and into the 1970s, and the Salomon Nordic System (SNS) binding re-invented this field entirely. Today cross-country binding systems have become as customized as their downhill counterparts of the 1960s.
- In 1937 Hjalmar Hvam broke his leg skiing, and while recuperating from surgery, invented the Saf-Ski toe binding. This was a metal clip with a pyramidal top that fit into a slot cut into the sole of the ski boot. When the boot was rotated forward, the slot on the toe eventually rose above the metal pyramid, allowing the toe to release from the ski. The system was considered with suspicion by professional skiers, especially when Olaf Rodegaard released during a race. However, Rodegaard credits the release with saving him from a broken leg. In the post-war era, Hvam sold several thousand pairs of Saf-Ski's, in an era when downhill skiing was in its infancy. Hvam continued to sell the Saf-Ski into the 1960s, but in 1966 his insurance rates increased so dramatically that he was forced from the market.
- 1939: The release binding, the Saf-Ski, was invented by Hjalmar Hvam.
- 1950: A dramatic advance was introduced as the Look Nevada in 1950. The Nevada held the toe centred over the ski using two metal fingers shaped into an upside-down V. The fingers were pivoted to allow motion to the sides, and centred with a spring. During a fall, sideways torsion could overcome the force of the spring and allow the boot to release directly to the side. This design was quickly copied by other vendors, notably Marker, and had the first real impact on the dominance of the classic fixed-toe bindings. By the late 1950s, there were about 35 different release toe bindings on the US market, most of which used a normal Kandahar-style heel cable.
- 1960: The first modern heel-and-toe binding was the Cubco binding, first introduced in 1950 but not popular until about 1960. A heel-release binding faced the problem that there was no obvious place to attach to on the heel, so the Cubco solved this by screwing small metal clips into the sole of the boot. This also eliminated the changes in performance as the sole of the boot wore down, or the geometry of the sole changed as the boot wore into the skiers foot. Marker introduced the Rotomat, which gripped onto the sole where it extended past the heel, and Look quickly followed suit with their Grand Prix design. By the mid-1960s, release bindings that worked on both the heel and the toe were common, and by the late 1960s the cable binding had disappeared from downhill.
- 1966: The introduction of plastic ski boots permitted the development of industrial standards for binding function.
- 1972: Injury rates began to fall with the gradual introduction of the Teflon anti-friction pad around 1972.
- Alpine: One problem with 1960s release bindings was that the boots were not standardized, and a binding that worked well on one boot might be dangerous on another, or might become dangerous over time as the boot shifted about. This led to the introduction of plate bindings, which used a metal plate firmly clipped to the sole of the boot, and bindings that clamped onto the plate. The plate could be easily removed for walking about. Plate bindings were popular in the US in the 1970s, notably the BURT Retractable Bindings and Spademan binding, but never caught on in any major way in Europe. As more and more of the downhill ski market came under control of European companies, the plate bindings disappeared, in spite of their excellent safety records. The disappearance of the plate and alternate systems was due to a combination of factors, notably the introduction of standardized hard plastic boots. Plastic was first introduced by Lange as a way of improving existing leather designs. As the new material spread through the industry, the sole piece was standardized to allow toe-and-heel bindings to clip on. Plastic had the advantages of being much firmer than leather, not changing shape over time, and having predictable friction characteristics wet or dry. Although plate bindings of the era had much better safety records, notably the Spademan design, the new boots and bindings could be easily adapted to any ski for any skier.
- Nordic: Problems with the geometry of the boot sole, which meant only certain boots would work, meant the Rottafella was not widely used. This problem was eventually solved through the same evolution of plastic components that changed the downhill market. In this case the use of highly flexible plastics allowed for a sole that was very strong torsionally and side-to-side, but still had excellent flexibility lengthwise, allowing the heel to rise as with a cable binding. This was standardized as the 3-pin system, which was widespread by the 1970s. A similar system with a 50 mm "duckbill" once existed for lighter setups, but is obsolete and no longer available. Unlike the 75 mm it was symmetric. It was the binding of choice for racing, prior to the adoption of skate ski racing, in the early 1970s. The 50 mm was also designated according to the thickness of the "duckbill" having either 7 mm or 11–13 mm thick soles hence these bindings often had two notches in the bail to clamp boots with different sole thicknesses.
- "DIN Setting Calculator". DINSetting.com. Retrieved 20 Dec 2013.
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- Mike Muha, "Nordic Integrated System ", Nordic Ski Racer, 26 January 2005
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- "New Telemark Norm (NTN)". Retrieved 16 November 2014.
- Lert, Wolfgang (March 2002). "A Binding Revolution". Skiing Heritage Journal: 26.
- Lert, Wolfgang (March 2002). "A Binding Revolution". Skiing Heritage Journal: 25–26. Retrieved 3 October 2012.
- Lund, Morten (September 2007). "Norway: How It All Started". Skiing Heritage Journal: 8–13. Retrieved 3 October 2012.
- Lert, pg. 25
- Lert, pg. 26
- John Allen, "Mathias Zdarsky: The Father of Alpine Skiing", Ski Heritage, March 2008, pg. 12
- "About Us", Rottefella
- Huntsford, Roland. Two Planks and a Passion.
- Masia, Seth. "Release! History of Safety Bindings". Skiing History magazine.
- Masia, pg. 27
- Masia, pg. 30
- Masia, pg. 29
- Seth Masia, "The Better Mousetrap", Ski Heritage, March 2003, pg 39-41