Stem (skiing)

The stem technique in skiing is a method for turning the skier. It is usually credited to the Austrian Mathias Zdarsky who developed it in the 1890s. Its variations gradually replaced the telemark technique in Alpine skiing.

The technique involves stemming the uphill ski. Stemming is pushing the tail of the ski outward—skidding it across snow—from a parallel position with the downhill ski to form a V shape where the tips of the skis are close together and the tails far apart. Initially the stemming ski has relatively little pressure applied—much less than half the skier's weight. After the ski is stemmed, most of the skiers weight is then transferred to initiate a change in direction.

The most basic form of stemming is the snowplough turn taught to first-time skiers. In this technique, the skier uses their lower legs to angle the skis outward at the tails and in at the tips, forming a shallow angle between the ski and upper body. The two skis are angled in opposite directions, forming a V-shape. In this position, the sideways force from one ski is balanced by the opposite sideways force of the other, leaving no net turning forces. However, both skis are creating backward forces, which add together and create significant drag, keeping speeds slow. To turn, pressure against one of the skis is relaxed so the snow pushes it back towards the body. This lowers the turning force on this side, thereby allowing the other ski to dominate and turn the skier toward the straightened ski. The turn is stopped by forcing this ski out again. This technique is simple and extremely powerful, however, it is also quite tiring as the skier has to keep the skis in position against the inward-directed force of the snow. It is very difficult to use on steeper slopes or higher speeds.

Stemming is also the basis of one of the most common types of downhill techniques, the Stem Christie. In this case the skis are normally kept parallel to each other, and to initiate a turn, only one ski is forced away from the body. This creates the same general position as the snowplough, and the same forces cause the skier to turn. However, as the skis are pointed parallel between turns and do not have to be pushed against the snow, the total workload is greatly reduced. And as the drag force is only generated during turns, this technique results in faster speeds. Whereas a snowplough might safely be used directly down the fall line of a given hill, a Christie on the same hill would result in higher speeds, and skiing this technique normally requires the skier to turn across the fall line almost constantly.

The ultimate development of the stemming technique is the parallel turn, a name that is no longer descriptive. In the classic parallel, the turning forces are generated the same way as the stem Christie or snowplough. However, while in the stem Christie only one ski is forced away from the body, in the parallel both skis are forced in the same direction at the same time. This means they remain parallel to each other as they rotate. When rapid parallel turns are quickly linked together, the upper body remains pointed down the fall line, and the lower body and skis are alternately driven into the snow in one direction and then the other. This was considered the height of good technique during the "hot dogging" era from the 1970s into the 1980s.[1]

Stem variants

The variations of the stem turn are:

These variants form the basis of the Austrian Arlberg Technique and instruction system developed by Hannes Schneider.

See also

References

  1. ↑ An excellent film of the classic parallel technique can be found in "Classic Short Radius Turns" on YouTube. Note that the skier's upper body remains pointed down the fall line, and their body moves only a small amount from side to side. Turns are initiated at the tip, and skidding progressively develops—note the amount of snow being thrown off the back of the ski as the turn develops. The skis can be seen to bend into arcs, but these are relatively modest.

[1] http://www.mechanicsofsport.com/skiing/manoeuvres/stem_turn.html

[2] http://www.ski-jungle.com/better-skiing/ch2.htm#stem-turn