How do we build skin skis? Constructing the optimal skin ski presents a handful of added challenges compared to traditional skis.
Most importantly, you want to make a ski that makes you forget that you’re skiing on a skin ski. To do that, you want to make sure you maintain the properties of the ski and make the ski feel and behave like your waxableskis. So how do we accomplish that?
Perfect kick and amazing glide
Madshus head of engineering, Bjørn Ivar Austrem, explains that one major challenge is that you need a skin that provides both secure and reliable grip as well as superior glide, and that is built like perfectly applied layers of wax. To achieve that, Madshus has developed a method to cut a pocket in the base that is deeper toward the ends of the skin, which in turn makes the skin protrude progressively toward the middle and taper to the ends – just like the perfect wax job.
The IntelliGrip® skins are set down into the base, rather than attached onto the base, to create smooth transitions between base and skin and ensure reliable grip without sacrificing glide.
“Progressive skin skis provide better grip than skin skis with a flat skin. When using a progressive skin, a ski that has a normal to high camber will provide better glide. So we found that by folding the skin into the base, we are able to maintain a high camber that keeps the skin off the snow when gliding while the skin is aggressive enough to make contact with the snow in the kick phase. Again, this is exactly the same principle as the perfectly waxed ski,” Austrem says.
The engineering conundrum
At the same time, this progressive skin construction presents a challenge, because the skin has to be folded into the base without compromising the properties of the ski, such as flex and stiffness. These key properties are a result of the thickness of the ski and the distance between the top and bottom layers of the fiberglass and/or carbon fibers that provide stiffness. Adding only a millimeter to the distance between the top and bottom layers of the fibers can make the ski significantly stiffer, and vice versa: placing the layers a millimeter closer can make the ski that much softer, Austrem explains.
“Once we cracked that code, we managed to construct a lively ski that’s stiff enough and fast enough to race.”
Of course, the actual skin matters as well.
“We use a blend of mohair and nylon on most of our models. The mohair provides great glide and reliable kick, while the nylon adds durability and prolongs the life of the skin. On the Redline IntelliGrip® , we use 100 percent mohair,” Austrem says, adding that the skin can easily be replaced if it gets worn out or damaged.