Deer feeding on corn in the snow at Snowshoe 

Charles peering in from the outside 

Jaclyn and Damon in a cave at Panthertown 

On Edge: The physics of carving

The blinding white fog from the morning storm cleared, and the crisp dry air seeped through the zipper of his jacket as John soared down ‘Alleycat’ effortlessly on six inches of fresh fluff. John had recently purchased the new Carve 11-16’s from Atomic and was enthralled by the ease at which he linked gigantic sweeping turns. A fountain of snow shot up from his semi-twin tipped skis and arced into what would be the only trace of his magnificent descent. John stopped momentarily and glanced upward as he grasped his quadriceps to relieve the burning sensation inflicted upon him by the 1000 feet vertical drop.

He grinned at the sight of the two parallel tracks above him that wove through the white pine forest. John turned his skis downhill once again to continue his journey; never once did the multitude of physical interactions occurring around him cross his mind, only the blissful serenity of the blanked landscape left a burning image in his head. He was oblivious to the mechanisms that accelerated his body downward and to the ski design that was more responsible for his beautiful turns than he was.

John, like most other skiers, doesn’t realize the subtle but profound advances in ski technology or take much interest in the forces involved in the thrilling experience. Parabolic skis are the paradigm of ski technology and general knowledge about their function can add a dimension of understanding to the formula of excitement and maybe even improve your skiing. The accumulation of knowledge in physics, the discovery and invention of new materials, and the intuition of passionate skiers have all combined and led to a carving revolution.

Evolution and History

Although the idea of skiing as a recreational sport has flourished mostly in the past century, the uses of skis are likely to exist as far back as 4000 years ago. Skis during this time were mostly used for hunting, warfare, and travel and were made of wood. The steel edge that every skier is so used to today was not incorporated into the design until 1928. Wooden skis were first challenged by aluminum skis, and then fiberglass, until carbon-fiber skis began replacing them around 1989. The ‘parabolic’ or ‘cut’ ski design found littering the walls of every ski shop today was actually conceptualized and utilized before the 19th century, but only in the last decade and a half have the deep side-cut skis controlled the market. The three most important breakthroughs in ski design technology have been the addition of the metal edges, stronger more flexible bases, and the side-cut.

Metal Edges: The addition of metal edges gave the skier a higher level of ‘grip’ when initiating turns and stopping.

Stronger Materials: With the use of aluminum, fiberglass, and then carbon fibers, skiers have been able to explore new terrains with confidence and ease because of increased support and durability.

Side-cut: The parabolic ski combined with metal edges and stronger materials led to a drastic improvement in turning, which revolutionized the way people skied.

Parabolic Skis

How is the parabolic ski different? The parabolic ski is different from a straight ski because it is not the same width along the entire ski. Parabolic skis are skinnier in the middle where the bindings are mounted and become wider as the ski extends to each end. Straight skis, as indicated in the picture below, have edges that are completely straight on both sides. The degree to which the ski width varies from the middle to the tip and tail of the ski is known as the side-cut. The extent of the side-cut can be easily visualized. Imagine placing a parabolic ski on the long edge, perpendicular to the ground. The 'cut' into the ski can be seen between the bottom edge of the ski and the floor. This area varies among skis, and the greater this area is, the larger the side-cut. Deeper side-cuts combined with a more flexible ski allow for shorter, quicker turns. Shallower side-cuts and stiffer skis work well for longer, sweeping turns.

How do they work? Parabolic skis work because of the advances that came before them. Without metal edges and without strong, flexible skis, the parabolic ski would not work. If you have ever had the privilege of riding a pair of parabolic skis, you know how easy it is to make beautiful turns. The feeling of ease that overcomes the rider can be obtained simply by putting the skis on their edge. How can it be so easy? When the rider initiates the turn the skis transition from being flat on the snow to becoming more perpendicular, similar to the way we visualized the side-cut before. This can also be seen in the picture at the top of the page. The skier in this picture is leaning into the turn and tilting his skis on edge, making the bases visible. When this happens, the weight of the skier and the centrifugal force directed in the opposite direction of the turn causes the ski to flex, which allows the entire metal edge of the ski to contact the snow. The increased width at the tip and tail of the ski hold their position on the snow while the middle of the ski flexes away from the direction of the turn. The resulting flexed ski forms an arc in the snow and the metal edges hold this position that results in a turn. The same maneuver with straight skis would only result in continued forward progress of the skier. No turn!

Why should you try it? Even if you are not planning on buying a new pair of skis, every passionate skier should at least try parabolic skis. Not trying this new ski would be like not trying out metal edges when they came out in 1928. A few days on parabolic skis and maybe a little instruction will change the way you ski, and you may never want to go back. The ease at which turns are initiated and the speed carried through the turn is enough to give any avid skier the ride of his life.