What Do the Numbers on Skis Mean?
Buying skis can be a daunting experience, especially if you are new to the sport. One way to get a better understanding of skis and the differences among them is to understand the “numbers” printed on the skis or in the name of ski. These are the key elements that will affect your experience on your skis and are the core details that will determine which ski to buy. These three elements are: width dimensions, length, and stiffness.
You’ll often hear terms like ‘radius’ and ‘sidecut’ thrown around, and it’s easy to be confused.
All modern skis have a set of dimensions; three numbers that determine their width. For example, a ski might have this printed on it: 122-86-115. This means they have a width of 122mm towards the tip (the widest point), a waist width of 86mm (under the foot), and a tail width of 115mm. Width dimensions inform two things: the radius, and the average width.
Put simply, the larger the waist width underfoot, the better the floatation of the ski in powder and the narrower the waist width, the better the ski will be able to perform on piste and transition quickly from edge to edge. As a reference, think about how snowshoes are better at floating on top of snow with a larger surface area.
The radius measurement, measured in metres, is the radius of the circle that would be drawn if you were to extend the edge indefinitely outwards. It is effectively the turning circle, and is suggestive of how long it will take the ski to complete the tightest turn possible.
For example, Slalom skis, which are designed for the quick and short turns of slalom race courses, have a “short radius” or 13m. This increases through Giant Slalom skis to 27m, Super G to 33m, and Downhill to 45m. Essentially, the larger the turns you intend to make while skiing, the larger your turn radius should be. For the average recreational skier, the radius will be somewhere between a slalom and giant slalom model.
Having a ski with a longer length is similar to having a ski with a greater width; it increases the surface area of the ski on snow. This offers greater floatation in deep snow and weight distribution, reducing friction between base and snow. With less friction, you will accelerate more quickly.
As a ski manufacturer increases the length of a ski but maintain the same width dimensions, the radius will increase (the difference in tip-tail and waist width is the same but spread over a longer distance, so the sidecut will be less), and this will stop the ski from carving turns as tightly. In simpler terms, a longer ski will give greater straight-line acceleration and maximum speed, but will enlarge the turning circle. With this in mind, Slalom skis (short turning radius) are short and Downhill skis (largest turning radius) are long.
The length of skis that you choose will depend not only on where and how you ski, but also on the type of ski that you choose. The Skiis & Biikes staff can help guide your decision on this.
Stiffness of the skis is important to understand because if you are unable to flex the ski, the radius means nothing and your ski will not perform. If you put your skis together, you will notice that they only touch at tip and tail, bending away from each other in the middle. This is called camber. When you carve a turn while skiing, pressuring the waist of the ski away from yourself, the flexed ski creates a curved shape (a reverse camber) in the snow. Following this curved shape, the ski travels round in a carved turn. The amount of pressure you need to apply to a ski to flex it from its normal camber shape into a reverse camber in a turn depends on how stiff it is. A stiffer ski will require greater power to flex it into a reverse camber, and will be less forgiving when travelling over bumps and landing air. If you push a soft ski too hard, it will give in and slide away from you, but a stiff ski will hold its edge and continue to track through the turn even when it is pushed very hard. A stiffer ski will snap back into its original shape more powerfully as the pressure is released, and this explosiveness can aid acceleration out of the turn.
Freeride skis are softer, as they need to be more forgiving to absorb bumps, hit landings, and won’t require as much pressure to carve on less stable terrain. Skis designed for on-piste performance are stiffer, as the skier presses much harder to push out of his turns and so accelerate out of a carve. Skis also differ in stiffness according to ability; beginner skis are softer than high-end models because the person using them tends not to have the ability to aggressively apply pressure in the turn.