Thanks Ghost, I would add the center seeking effect of Gravity to the top of the turn and how even without an engaged edge it will pull us into the next turn. Yes the terrain of choice is very shallow but the net resultant force of support under both skis and Gravity is still slightly off vertical. Meaning the net force we still call Gravity pulls us down the hill even there. The secret is in reducing the edge that is supporting us and causing the traverse in the first place. I pulled out my 1964 manual and the 2007 certification guide from PSIA and noticed the big difference in how the maneuver is described in each. I will offer a small portion of both texts but since both are in hard copy form transcribing both here is a large task I am not going to take on right now. The 2007 guide was available at PSIA's site but Bob may be the person who can post that since he is the author and there are copyrights that may apply.
The 1964 version includes an uphill stem (or bilateral hopping stems if doing a wedge straight run) to get the skis into a converging position. From there the skier tips the shoulders to the outside of the turn to weight the outside ski. The outside shoulder is held back to create upper body counter. On the equipment of that era those moves seemed reasonable and were in large part an offshoot of the Austrian Arlberg system. Instructors who trained back then adopted this final form and if they did not change what was once the standard it would still be correct by that dated standard. The additional weight placed on the uphill ski would indeed increase reaction force under that ski and that in effect would push us into the new turn. A particular note missing in that manual was the reduction of edge angle of the downhill ski though and in effect this introduces vaulting to overwhelm the edge platform under the downhill ski.
Contrast that fairly simple and straight forward description with what Barnes and the PSIA Alpine Education Committee wrote in the 2007 certification guidelines that are three pages long. Of particular relevance I am including some overall qualities as they describe them followed by some maneuver specific descriptions of the basic maneuver and finally a few of the disqualifiers that I feel are of particular relevance to this discussion. Hopefully this doesn't get too verbose but here they are...
Stance is described in the commonalities & principles of all basic reference standard maneuvers as follows;
"Open, uncontrived, functional, and athletic, optimizing movement options, independent leg action, and muscular and skeletal efficiency.
The maneuver specific description includes all the basic fundamental principles of basic offensive turns at the beginning level.
- Movements, speed, and line are reasonably attainable by a typical beginning skier...
- Range and intensity of movements are appropriately minimal, reflecting the very low speed, very gentle terrain, and embryonic skill development of the beginning skier...
- Consistent natural wedge is the outcome of the open stance, active steering movements, and tactics that keep speed and forces to a minimum...
- It is a characteristic, not a principle, and outcome, not an intent, and certainly not a defensive braking move. The wedge is not forced!...
- Skier demonstrates exclusively "positive movements"- when turning right nothing moves intentionally left. The uphill tail is not pushed out at turn initiation and the wedge does not open wider...
- Gliding wedge is constant and natural, unforced, with no change in size. Skis stay on opposing edges as the skier's body remains consistently between the skis....
Disqualifiers, or at least some of them are as follows;
- stance - ineffective, contrived, or severely misaligned to the extent that it interferes with the required technical or tactical elements.
- Consistent or dominant upper body or pushoff-based rotary mechanics. these include rotation and rotary pushoff, counter rotation, and a blocking pole plant.
- Sequential (outside leg first) movement, or any leg movements that twist the outside tail into an increased skid during initiation or shaping phase of the turn.
- Failurwe to release edge of downhill ski at turn initiation; "pushoff" initiation.
- Braking, intentional skidding, pushing to edge, checking, platforms.
- insufficient engagement, causing slippage and loss of steering control.
- Excessive engagement, causing edge lock and loss of steering control.
- Active weight transfer, especially if it causes a negative movement of the body (cm) through transition (ie, pushoff)
- Forward leverage causing the tails to wash, or otherwise interfere with steering efforts
- loss of speed control, or speed control from braking
So there you have some of the more recent thinking about wedges which also apply to an extent to Wedge Christies (matching being an obvious difference).
BTW the wedge and matching is described as spontaneous and in the case of the wedge Christie they include the following
- Matching also resulting from continued steering of the inside tip into the turn. Speed and pitch of the hill dictate the ti,ing and rate of matching.
When we get to parallel turns the obvious difference is corresponding edge usage clearly seen in somewhat equal edge angles of both skis at all times, a slightly narrower stance than the wedge Christie (reflects a student's improved balance and confidence), simultaneous edge release from reducing edge angles, consistently parallel skis as a result of refined active steering movements and appropriate tactics, and a lack of any contrived stances and negative movements (moving any part of the body away from the turn).
Beyond that lies a whole lot of activities and experimentation where the student may indeed assume contrived stances to discover their effects on the outcome and learn how to recognize when their stance gets out of the basic balance zone, as well as how to correct those common errors. But all of that is a topic for another day and another thread. Wedge to parallel is a journey where we establish some basic fundamentals in an easily digestible and usable form and then go about refining those movements as the student's skill level improves. Inside ski usage certainly changes but not as a function of anything more than speed. Try to perform basic parallel turns at a snails pace and you will wedge, or wedge Christie if you up the speed a slight bit. I am sure some here will refute some, or all of what I included here but in doing so I hope they provide just as much detail from their national organization that published that information. Please also include date of publishing because like PSIA sometimes that date is a factor in what was written.