Wedge vs. Stem = Offensive vs. Defensive
CDNGuy--I agree pretty much with the replies you've already received regarding stems (stem christies) and wedges (wedge christies). But I'll add my take on it.
First, "wedge" is historically a generic term describing any time the skis are in a converging (tips closer than tails) orientation and on opposing (both inside) edges, which would include "stems" and the proverbial "snowplow"--so perhaps I was being a bit overly sensational in my original statement. "Stem" is more specific, though, referring to a push of the tail of either ski out away from the other ski (from German "stemmen," meaning "to push against"). In that sense, a stem is always a defensive movement, generally checking speed and/or pushing the body away from the direction of a new turn.
Instructors have long differentiated between a "braking wedge" and a "gliding wedge" and in modern times--meaning mid-1980's on--American instructors have used the term "wedge christie" specifically to define an offensive-type turn distinctly different from the traditional "stem christie."
Traditionally, "stem christies" are turns that begin with a true stem--a deliberate push of one or the other ski tail out. There are many variations, but all begin with either a "downstem" or an "upstem." "Downstem christies" begin by brushing the downhill ski tail down until its edge engages, checking speed, and establishing a solid "platform" from which the skier pushes or rebounds (bounces) toward the other ski--"up and around." An "upstem christie" involves extending from an engaged downhill ski up the hill while pushing the uphill tail up and out, then transferring weight to the stemmed uphill ski and continuing the turn. In both cases, the ski tails are eventually pulled together ("closed") to finish parallel (the "christie" phase).
PSIA's "Center Line(TM) Model," developed in the mid-1980's, defined a "new" type of offensive turn (made to GO a new direction, not to slow you down directly) that begins with a release of the edge of the downhill ski (opposite of the platform I described above) and a passive drifting or active guiding of both ski tips down the hill and into the new turn. Neither tail is pushed out at all. Furthermore, the Center Line Model described the characteristics of this same fundamental turn and movement pattern as they typically evolve from beginners' first turns through advanced and expert.
It turns out--and this is easily demonstrable on the hill even with today's skis--that at very low speeds, especially combined with low skill level, skiers inevitably form a wedge as they enter such turns, whether they try to or not. Thus the first "milestone" of progress on the Center Line became the "Wedge Turn." The wedge involved in this "new" Wedge Turn is very different from the classic "snowplow" or tail-pushed stems of more traditional teaching progressions. In this Wedge Turn, the wedge is not intentional,
and it is not
used for braking. The intent is simply to turn both skis into the new turn, but for various reasons (another post, perhaps), the outside ski tends to turn more quickly than the inside ski, and a wedge just "happens."
It's important to understand that these modern wedge turns begin with a release of the edge of the downhill ski, followed by guiding/steering the tip of the downhill ski down the hill and into the turn. They are truly meant to "go that way" down the hill, not to "stop going this way," or to slow down. Obviously, when you turn from across the hill to down the hill without brakes on, you're going to gain speed. This is why I insist that it is counterproductive to describe turns as a way to control speed. You have to want to gain speed, not lose it, when you start a good turn--because you're going to! And if you don't want to go faster, you'll make a different type of movements (so will I)--defensive, braking, checking, skidding, stemming, and the like. Sure, when you continue the turn, finishing it again across the hill or even up the hill, the hill will slow you down again. But the thought that triggers the start of a new turn must be the desire to gain speed--not to slow down.
I digress--back to the difference between a "wedge" and a "stem." Perhaps the clearest illustration is the comparison of the classic "stem christie" and the modern "wedge christie," which are in fact polar opposites. Let's compare a Wedge Christie right turn with a classic Stem Christie right turn, both beginning from a right-to-left traverse across the hill with skis parallel. This diagram showing the difference between the "matching" of wedge christies and the "closing" of stem christies may help:
The Wedge Christie (to the right) begins by rolling the downhill (right) ski to the right until its edge releases, accompanied by a movement of the skier's body down the hill (to the right) to remain in balance. As the edge releases, the skier guides the tip of the right ski to the right, down the hill and into the turn. The left ski follows, but typically (at this level) turns more quickly, causing a small gliding wedge and gentle brushing of the outside (left) ski through the turn. Speed increases as the skier glides down the hill. The skier tips somewhat into the turn for balance, and continues to guide the right ski to the right--literally pulling its tip away from the left tip--throughout the turn. At some point, this steering effort ("right tip right," followed by the left tip) pulls the skis parallel (see the "Matching" diagram). Continued guiding of the right tip right shapes the turn until the skier decides to finish the turn and traverse the other way or start a new turn ("left tip left"). Everything the skier did, from start to finish, involved movements to the right ("positive movements"). Matching from wedge to parallel resulted from pulling the ski tips apart.
Now let's lookat a classic "upstem" stem christie to the right. From the same traverse, the skier rolls the right ski uphill
(to the left) to make sure its edge is fully engaged, then brushes the left ski tail uphill into a stem, moving his body uphill (to the left) with the ski, for balance. A good push off from the downhill ski transfers weight and balance to the left ski, which is now skidding through the turn and scrubbing away speed. Finally, at some point, the skier pulls the tail of the right ski over toward the left ski, "closing" the skis to parallel, and finishes the turn in a new traverse to the right. Every movement the skier made in this right stem christie was to the left--away from the turn and up the hill to start.
The wedge christie mantra could be "right tip right to go right," while the stem christie mantra would be "left tail left to stop going left." Right vs.
left, tip vs.
tail, go vs.
stop. . .the two could not be more opposite! Note how the arrows in the illustration point in opposite directions. Offensive (wedge) or defensive, "go that way" or "stop going this way," "gain speed" or "slow down"--these are all legitimate intents that dictate turns for all of us. But it's important to understand the differences. And it's critically important to understand that, if we or our students want to develop the good offensive habits of expert skiers, we have to make sure we start with the same offensive intent.
As these turns evolve with skill and speed, the wedge christie becomes an offensive, gliding and carved parallel turn, still guided by the "right tip right to go right" mantra from start to finish. And the Stem Christie becomes a parallel forced braking skid, like a hockey stop, still guided by the "left tail left to stop going left" thought.
Tdk6--on one level it may be merely a subtle difference in semantics, but from my experience, the change from turning to control speed to turning to control direction represents a profound transformation, a true paradigm shift. In this sense, telling them that turns are for speed control is, in my opinion, one of the most limiting and devastating things we can teach our students! Speed control is certainly not the motivation for Bode Miller's or Ted Ligety's or Janica Kostelic's turns, is it? They turn to go where they want to go. So do I.I do not turn to control speed. I turn to avoid the very need to control speed!