Parallel turn
 |
| Skiing techniques |
|---|
The parallel turn in alpine skiing is a method for turning. It is based on the idea of rolling the ski onto one edge, allowing it to bend into an arc. The ski then follows the arc shape and turns, without sliding. This is in contrast to earlier techniques like the stem Christie, which accomplishes turns by sliding the ski outward from the body ("stemming") to generate sideways forces. Parallel turns generate much less friction, and are more efficient both in terms of maintaining speed and skier effort.
Parallel turns require a solid connection from the skiers lower leg to the ski, so that it can be rotated on-edge. This was difficult to achieve with early ski equipment, and the technique was generally limited to racing where its higher performance was useful. The introduction of composite skis, metal edges, releasable clamping bindings and stiff plastic boots all fed into an evolution of equipment that allowed the parallel turn to be managed even on beginner equipment. By the late 1960s it rapidly replaced stemming for all but very short-radius turns. The introduction of "shaped" or "parabolic" skis in the 1990s furthered this evolution through the ease of carving. Today the technique is taught to all but complete novices.
Basic action
Modern skis feature a "sidecut" pattern, normally starting with a wide nose, narrowing through the middle, and then widening again at the tail. If the ski is rotated about its long axis, it would normally contact the snow only at the tip and tail, the widest parts of the ski. However, when the skiers weight is considered, located near the middle of the ski, this picture changes. As the ski is extremely stiff laterally, the ski responds to this weight by bending outward in the middle, until that section of the sidewall is also in contact with the snow. The result is that the ski is bent into an arc, with the nose and tail on the inside of the arc, and the middle of the ski pushed out. When pushed forward, the ski will naturally follow this arc to follow a circular outline.
The parallel turn relies on this arc. The skier initiates the turn by moving their knee laterally in the direction of the desired turn. The motion of the knee is translated through the calf to the high cuff on the ski boot, through the boot to the binding, and then to the ski. This causes the ski to rotate up on edge, creating the arc that turns the ski. The knee is rotated back to the neutral position to stop the turn. Both skis take part in the turn, although in practice the ski on the outside of the turn had more pressure applied and leads the action.
Shifting the legs to the side would normally result in the movement of the center of gravity, this is normally compensated by moving the hips in the opposite direction. The resulting in a motion that it appear the skier's upper body is not moving while the legs are moving about. As the turn progresses the skier's weight remains centered fore-and-aft. The skier pressures the front of the ski in an effort to keep the longitudinal center of gravity of the skier's mass over the toes.
The parallel turn can be improved through dynamic "weighting". Turns are often linked into a series of continual arcs, one direction then the other. By lifting the body through the middle of the switch from one side to the other, the arc shape is released, and then set again by applying the weight again once the knee is moved into the new position. This leads to a bobbing motion of the upper body, synchronized with the turns.
Changing technique
In the past, the "perfect" parallel turn described above would result in a very long turn radius. This was due to the limited amount of sidecut on most skis, which was in turn a limit caused by the torsional strength of the ski. With older construction techniques, a wide sidecut would not result in a tighter arc when rolled on the side, instead, the ski would flex so the tips and tails were lying flatter to the snow.
In this era of "skinny skis", paralleling and stemming were mixed together depending on the situation. Often the turns would be initiated with parallel turns and then evolve into stemming once the turn was initiated. At lower speeds or times where greater turning power was needed, the action devolved to more stemming. It was not uncommon even for pure stemming turns to be called parallel, if the skier rotated the legs in unison.
Turning the ski using a parallel turn with skidding is the opposite of a carve turn. In a properly carved turn, the edge of the ski does not slide laterally during the whole turn. In the 1990s ski design developed with radical side-cut skis to make this require less skiing effort, as skis were progressively widened at the tips and tails relative to the waist. With this shape, applying one edge to the surface significantly curves the ski, resulting in its turning.
Most ski curricula begin with the snowplough turn, then introduce the stem turn, and finally progress to a parallel turn. As of the early 2000s, some curricula begin with the parallel turn.