The development of equipment precisely accompanies the development of turning techniques on skis. The addition of sidecut to skis enabled a much more precise turn. A sidecut ski has a waist that is narrower than the tip and tail*.

Sidecut allows skiers to take advantage of the physics of an arc. This is fundamental to how skis turn. When a ski is put into an arc on its edge, it must describe the radius of a circle. There is no other way for it to move; in fact, as long as the edge is cutting into the snow and the ski is sufficiently bent into the snow, a sidecut ski must transcribe a circle until the bend is released. At which point, the ski will start to slide.

I like to demonstrate this effect with a little piece of cardboard or other thick paper cut into the shape of an extremely sidecut ski.

You can try the following experiment. (Do try this at home: there’s no danger at all!)

Take your little ski model and put it on edge but not bent, absolutely straight. Place your “ski” edge onto something like a table or other relatively smooth surface. Observe what part of the edge is touching and what is not touching.

On edge, only the tip and the tail area will touch the surface.  The waist portion of the ski will not touch. If this were a real ski on real snow, it would slip with little grip, little control. That is the horrible feeling of one’s skis sliding uncontrollably downhill. Perhaps you’ve experienced this**?

Now take your model ski and bend it such that the waist is below the tip and tail bending the ski until the entire edge of the ski model is now touching the surface. Don’t worry about skiing correctness. This is just for demonstration purposes. Remember, your little model probably has a far more extreme sidecut than a real ski. Maybe you have the ski almost perpendicular to the surface in order for the entire edge to make contact? That’s okay; this is just a demonstration model.

You can now feel that the easiest way for the model ski to move (tip to tail) on it’s edge is in the natural circle caused by the arc of the edge.

The experiment demonstrates 2 important things:

1. A ski must be on edge in order to turn properly
2. A ski must be bent into an arc in order to turn properly

By “bent” I mean that the center of the ski is pushed down so that the ski waist is “below” the tip and tail. The bottom of the ski is the outside of an arc. The top of the ski is the inside of an arc.

This is the carved turn. This is the goal of modern skiing; this is the Holy Grail, whether telemark turning, parallel turning, what-have-you.

But wait, you will likely have 2 skis on your feet, yes?

The same edge of each ski must bend into the same arc – they must describe an arc together. This means that either the right edges of both skis or the left edges of both skis are in use. That is the skis are on the edge to the same side of the skier (skier’s left or skier’s right).

For any of the parallel turn types (telemark is one of the parallel turns), never are the inside edges of both skis or the outside edges of both skis used together. If the edge pointing to the right of the skier (a left turn) are used on both skis, one skis outside edge and one skis inside edge will be used together. Both edges will be pointing to the right of the skier.

And, both skis must be placed into a similar arc so that they will turn together, describing a single turn.

Ski bends and edging don’t have to have rocket science precision. Luckily, our bodies can accomodate a certain amount of fluff and inaccuracy between the skis, adjusting as the turn unfolds.

If the skis are on opposite edges, you turn in 2 different directions. This is what happens when the outside ski is turning left and the inside ski is turning right or at the very least, resisting the left turn***.

And, what I’ve described here is true whether telemarking or any other parallel turn. The skis must be on edge together and weighted similarly (that is, bent into a similar arc)

So, how to get both skis onto the edge?

This process again takes advantage of the physics of the ski, believe it or not. Remember our little model?

Place your model flat on the surface, not on it’s edge. Feel how easily you can slide it in any direction. That is the property that allows us to change from one edge to the other.

We finish our turn on edge and as weighted as necessary to slow us down sufficiently for the steepness of the slope.

The process of the beginning of the next turn is

1. Stop pressuring the skis into a bend (an arc)
2. flaten the skis onto the snow
3. roll the skis on to the new turning edges
4. begin the process of pressuring the skis so that they will describe the new arc

Seems simple, huh? Getting the feel of this and trusting it is a part of the mastery of skiing. For this process is entirely somatic.

For a series of fast, fall line turns, the edge change must happen in less than a second. The process must be smooth and elegant, especially the process of weighting or bending. Too much weight too soon or applied as a sudden jerk and the skis will tend to bite too hard, too fast; the energy of that bite will be hard to accomodate in the body. And the turn is likely to be lost. The tendency is to let go of the bend, which then causes the skis to slide.

If the skier is too slow when starting the bend (weighting) of the skis, this causes an uncontrolled slide – gravity is still a force whether the skis are edged or not. Remember our model when it had only the tip and tail making contact? Either late weighting or else sudden, jerky weighting work well enough on a beginner slope without much gravitational pull. These faults can be deadly on a 35 degree pitch, as gravity magnifies the mistake.

And for the telemark turn, somewhere in the process of releasing the edges and unweighting the skis, then rolling the skis over into the new turn while they are light, and then beginning the weighting to make them carve the next turn, we have to change leads. Are you tired yet?

But there you have it, I hope that I’ve explained a few simple physics about what makes a ski turn? And, I hope that I’ve explained a little bit about how to get from turn to turn? Skiers make this process happen while one is essentially falling down a hill.

As my friend David Kemintzer says: “In skiing, gravity is your friend”. True enough. Along with that little slick of melting snow on ski bottom that causes the skis to slide. Without the sliding water and gravity, there would be no skiing.

The invention of the sidecut ski added the physics of the arc to gravity’s pull on the sliding ski.

Footnotes:

*The tip of the ski is often called “the shovel”

**When skiers talk about “tailing out” at the end of a turn, most of time, it is because their ski is not bent into a sufficient arc at that point.

***This is a classic mistake of beginning to intermediate skiers trying to get beyond a stemmed or snow plow turn. That uphill ski will seem to have a mind of its own****. The way you spot this problem is that the uphill ski seems always to have to be placed into position after the turn has started on what will be the downhill ski. Sometimes, this is a function of poor boot cant or ski cant – it can be a matter of equipment preventing both skis from being put on edge together.