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Perception vs. Reality: Ski Tracks; What is really happening? - Page 4

post #91 of 131
Quote:
Originally Posted by HeluvaSkier
That is what is coined the 'superphantom'?
No. The Super Phantom is the Phantom with some refinements added. Detail in the DVD Anyone Can Be An Expert Skier 2 at roughly 18 minutes.

The Phantom is basically lift and tilt.

Some of the refinements that make the Super Phantom:

Flexing to release, traversing on the uphill edge of the uphill ski while you tip the free foot, pulling and holding the free foot back through the turn, more tipping throughout the turn.

In the early lessons of PMTS the focus is on lifting the inside ski which has led to a general misconception that PMTS only teaches you to ski on the downhill ski. However as you progress though PMTS you learn to ski on either ski at anytime and lifting the inside ski is no longer stressed...which makes sense because you may have weight on that ski. Most of the time I don't lift my inside ski.
post #92 of 131
Quote:
Originally Posted by HeluvaSkier
which makes perfect sense if you think about it you have 1 meter to get the inside ski onto its new track or 5m to get the inside ski onto its new track...
Is that what you meant to write?
post #93 of 131
You know, I could be convinced that a little inside knee angulation is not such a bad thing so long as there is almost no weight on it.
post #94 of 131
Quote:
Originally Posted by Ghost
You know, I could be convinced that a little inside knee angulation is not such a bad thing so long as there is almost no weight on it.
The question would be 'why would you do it'? You have the option of creating the same inside edge angle but with your knee lined up so that you hip drops a bit farther into the turn. Does't that create a stronger turn?
post #95 of 131
To get that inside ski out of the way and into position even more quickly, even as the hip is dropping in as quick as it can for a wicked lean-angle high-g turn.
post #96 of 131
Thread Starter 

Something for the Weekend & Wrap-up before CM Diagrams

Bullet points for each track scenario:

Constant Track Width:
  • The inside ski must track a smaller radius than the outside ski.
  • Horizontal separation in transition is larger than horizontal separation at the apex of the turn.
  • As the edge angle increases it becomes increasingly difficult to continue carving a smaller radius with the inside ski – the inside leg/boot will eventually be ‘in the way’ and balance will also be effected.
  • Basic low edge angle turns will be very easy and able to be done by actually carving the inside ski (say… open parallel turns…), but once speed and edge angle increase steering of the inside ski will be needed to maintain the inside ski (smaller) radius.
  • In high edge angle scenarios creates a stance in transition that is (IMHO) too wide and makes the skier very bow-legged. [NOTE: This is an important factor that effects the movement of the CM and where it falls in the turn]
Convergent/Divergent Track Width:
  • Variable width tracks with perfectly parallel skis will require the inside ski to be dragged across the snow by flexion/contraction as vertical separation increases toward the apex and then decreases toward the transition.
  • Without the dragging of the inside ski mentioned in the previous bullet (that creates track separation) increasing the edge angle would pin the legs together (as vertical separation would not be possible) and likely the outside ski would disengage.
  • In a high edge angle turn with perfectly parallel skis will still require steering of the inside ski in order to get the inside ski to track the proper radius and stay parallel with the outside ski. It is nearly physically impossible (or at least VERY inefficient) to get the body into the position where you can create an edge angle on the inside ski that will allow you to carve the needed radius for this ski (high edge angle turn).
  • Constant steering and lateral dragging are inefficient movements (few people actually ski like this), and are eliminated by a very small redirection of the inside ski at the top of the turn (what I have been trying to point out).
  • The importance of this redirection is that it puts the inside ski on the proper radius in order to allow the inside ski to be carved at a lower edge angle than the outside ski.
  • Dragging of the inside ski and constant/excessive steering is not needed to produce high edge angle turns when a lot of vertical separation is employed/needed.
  • When you see a WC racer with slightly divergent skis at the top of the turn, or convergent skis at the bottom of the turn (meaning skis pointed toward or away from each other) the inside ski has actually undergone a tiny, nearly un-noticeable, redirect that has allowed the skier to carve from one turn to the other easily and efficiently (no dragging of the inside ski, and no constant steering to keep the two skis parallel continuously).
Later

GREG

[Thanks ]
post #97 of 131
Greg
Have you got any photos of WC racers like you mention in the last part of your post?
I'm good with everthing else, just not clear(not necessarily disagreeing) on that part.
post #98 of 131
Skifex,

Didn’t want you to think we’d missed your post on Ski Characteristics affecting the CM line… Heluva will be posting a new thread before too long discussing CM path in relation to Base-of-Support path(s) and I suspect people are just holding on to their comments until then.

For what it’s worth right now, I certainly agree with your point that the sidecut/length/flex-pattern of a ski will directly affect the CM/Base-of-Support paths when we incorporate the skier’s height and weight into the formula. The specific Technique employed also comes into play, as do a host of other factors. Should be an interesting (perhaps wild & wooly) topic.

(I also like your comment about some ski designs ‘compelling’ us to stay off the inside ski. We’ll need to pick up that idea in the new thread when it comes about)

.ma
post #99 of 131
Quote:
Originally Posted by SLATZ
Greg
Have you got any photos of WC racers like you mention in the last part of your post?
I'm good with everthing else, just not clear(not necessarily disagreeing) on that part.
How about this one of Bennie Raich from http://www.ronlemaster.com/?
post #100 of 131
Contrast that one (SL) to this one (GS). Much less redirection here:

Forgot to mention... this is Rahlves...
post #101 of 131
Thread Starter 
Thanks Steve. Did you want to comment on the potential difference (or why it exists) between GS and SL?
post #102 of 131
Thread Starter 
SLATZ: I posted two links in post #61... there are more hanging around LeMaster's site as well, but the two I used were pretty good examples.

http://forums.epicski.com/showpost.p...5&postcount=61
post #103 of 131
Quote:
Originally Posted by HeluvaSkier
Thanks Steve. Did you want to comment on the potential difference (or why it exists) between GS and SL?
Not yet. I'll leave that for the next thread...
post #104 of 131
I don't see actual re-direction in any of those sequences. The skis appear to converge and diverge at points because of the leverage that is applied. The convergence appears as the unweighted ski is leveraged forward and the tip is on the snow while the tail is slightly lifted. The divergence at the gate in the Raich sequences is from weight shifted back and inside, causing the outside ski to turn less.
While the skis appear to converge and diverge I don't agree that it's a result of re-direction. (which I would define as some sort of torque or rotary at the ski)
As for the GS sequence, I think I posted that GS turns, that aren't pivoted, tend to be clean RR tracks with uniform horizontal distance.
post #105 of 131
SLATZ, this is where it gets difficult to find the common terminology necessary. I see intentionally divergence/convergence in the Raich sequence, especially in images 2, 5, 7, and 10. How is he doing it? Well, given the angles his legs are making, he's doing it by tipping his foot (by rotating his femur). Why is he doing it? To tighten the turn in the way necessary to maintain the line he's chosen, which is tighter than the line which is possible by riding the sidecut of the ski.
post #106 of 131
I see him rotating his femur to edge (or tip) the skis but I don't see him applying a twisting or rotary to the ski on the snow.
The "internal rotary" of the femur puts the ski on edge but does not change it's direction on the snow. The resultant carve does that.
10 fore sure involves no redirection. The outside ski has stopped carving because his weight is back and shifted inside. (like in the old PSIA Centerline Diverging Parallel)
post #107 of 131
Quote:
Originally Posted by SLATZ
I see him rotating his femur to edge (or tip) the skis but I don't see him applying a twisting or rotary to the ski on the snow.
The "internal rotary" of the femur puts the ski on edge but does not change it's direction on the snow. The resultant carve does that.
10 fore sure involves no redirection. The outside ski has stopped carving because his weight is back and shifted inside. (like in the old PSIA Centerline Diverging Parallel)
Between images 7 and 8 his ski changes direction but isn't on the snow and certainly isn't carving. The redirection may (or may not) be unintentional, but it's there. And, I would argue, it serves a very useful purpose.

I disagree about 10. Angulation puts solid pressure on that outside ski and it's still carving. The inside ski is carving less as can be see through the lower edge angle.
post #108 of 131
Thread Starter 
SLATZ, I guess to put it in simple english minus all of the technique babble - a skier cannot have divergent ski paths with out there being some sort of ski/tip redirection.

This very well may be the result of other moves that the skier is making, and it is likely NOT a concious move; but the fact remains that the ski are not parallel... "not parallel skis" means that at some point one ski or the other has been effected by a redirect movement that adjusts its turn radius and direction. If the outside ski were changing from one radius to another radius I think that we would all agree that it was redirected - somehow. Because the inside ski is not engaged it becomes more of a grey area and likely a moot point for anyone really interested in making turns like this. No coach would ever go out and say "diverge the inside ski at the top of the turn." The fact of the matter is that in order to keep efficiency of the turn the skis diverge (no dragging like I explained above), simply because the skier is smart enough to not drag their inside ski, and they realize that efficient movements while skiing do not always mean perefectly parallel skis/tracks as long as the CM takes its desired, natural path through the turn without extensive "CM movements" on the skier's part.

...and that should ready us for the CM discussion I think...

Later

GREG
post #109 of 131
In 7 and 8 the skis are parallel. The reason they don't appear to be is that in 7 the tail of the right is lifted(light) and in 8 the left's tail is lifted. The lifting is because of forward leverage, not a concious lifting.
In 10 he shifted weight back too soon and the ski didn't complete the direction change (it also did not load and provide "pop") I have to admit he's re-directing his CM in the direction he wants to go (because the ski isn't going there). Racing is always a series of "misakes" that the athlete makes to try to get the little extra speed. My experience of watching these guys tells me that 10 would probably be followed by what appears to be a stepping move of the right ski when balance was established on the left. The tracks would not look like anything we're talking about here. Racing is almost never "text book" skiing and photomontages are good but not as good as frame by frame. Also two dimensional photos make things appear differently. You need to be able to visualize them in three dimensions.
Most people don't agree with my analysis of these things. I've spent a lot of time doing frame by frames and on hill observation of racers over the last thirty years and I'm pretty comfortable with them. The other thing is that every time you try to put motion into words you get a lot of variation in what the words mean to different people. I'm sure if we were all standing on a hill together there'd be very little disagreement.
post #110 of 131
Quote:
Originally Posted by HeluvaSkier
SLATZ, I guess to put it in simple english minus all of the technique babble - a skier cannot have divergent ski paths with out there being some sort of ski/tip redirection.

This very well may be the result of other moves that the skier is making, and it is likely NOT a concious move; but the fact remains that the ski are not parallel... "not parallel skis" means that at some point one ski or the other has been effected by a redirect movement that adjusts its turn radius and direction.
If you put the inside ski on a higher angle than the outside ski it will diverge. Is that a 'redirect movement' as used in your quote above?
post #111 of 131
Quote:
Originally Posted by SLATZ
In 7 and 8 the skis are parallel. The reason they don't appear to be is that in 7 the tail of the right is lifted(light) and in 8 the left's tail is lifted. The lifting is because of forward leverage, not a concious lifting.
In 10 he shifted weight back too soon and the ski didn't complete the direction change (it also did not load and provide "pop") I have to admit he's re-directing his CM in the direction he wants to go (because the ski isn't going there). Racing is always a series of "misakes" that the athlete makes to try to get the little extra speed. My experience of watching these guys tells me that 10 would probably be followed by what appears to be a stepping move of the right ski when balance was established on the left. The tracks would not look like anything we're talking about here. Racing is almost never "text book" skiing and photomontages are good but not as good as frame by frame. Also two dimensional photos make things appear differently. You need to be able to visualize them in three dimensions.
Most people don't agree with my analysis of these things. I've spent a lot of time doing frame by frames and on hill observation of racers over the last thirty years and I'm pretty comfortable with them. The other thing is that every time you try to put motion into words you get a lot of variation in what the words mean to different people. I'm sure if we were all standing on a hill together there'd be very little disagreement.
Well, you're certainly right about one thing: I don't agree!

In 7, both skis are on the snow. In 8, the left ski is lifted in the tail, likely as a result of energy released after 7. In 8 they are parallel, but they definitely aren't parallel in 7. And, given his body position in 7, there's no way that I'll be convinced that he's right ski is off the snow, since it's not off in 6 or 8, and, in fact, there's more pressure on it progressively from 6 through 8 and beyond. The snow in 5 and 6 from the right ski show that it's on the snow.

In 10, he's very balanced over his skis, and, in fact, has moved forward with respect to his skis relative to 9 (his right leg is straighter, his hands higher, his CM more forward). He's standing on that right (outside/downhill) ski.

I know... proof that two folks can see very different things from the same photomontage. But, does that make it worth not doing? I don't think so. I am learning a lot--especially by not acquiescing when I disagree. Thanks for engaging in conversation with me!
post #112 of 131
How about this one (also from Ron LeMaster's site)?
post #113 of 131
Quote:
Originally Posted by Max_501
If you put the inside ski on a higher angle than the outside ski it will diverge. Is that a 'redirect movement' as used in your quote above?
Nope.
post #114 of 131
Thread Starter 
Quote:
Originally Posted by Max_501
If you put the inside ski on a higher angle than the outside ski it will diverge. Is that a 'redirect movement' as used in your quote above?
Steve is right - but I am glad you mentioned it Max. The point of this is to show that the inside ski does not have to be on a higher edge angle and most often is not, but still diverges anyway. Watch any racer ski - especially the photos we are using... It is physcially impossible for them to put that inside ski on a higher edge than the outside ski in most cases... at least physically impossible to get it far enough on edge that it will carve the proper turn radius itself... You would end up standing like you have a 3' diameter beach ball between your legs at the top of the turn. Something tells me that you probably don't ski like this...

Later

GREG
post #115 of 131
Quote:
Originally Posted by HeluvaSkier
Steve is right - but I am glad you mentioned it Max. The point of this is to show that the inside ski does not have to be on a higher edge angle and most often is not, but still diverges anyway. Watch any racer ski - especially the photos we are using... It is physcially impossible for them to put that inside ski on a higher edge than the outside ski in most cases... at least physically impossible to get it far enough on edge that it will carve the proper turn radius itself... You would end up standing like you have a 3' diameter beach ball between your legs at the top of the turn. Something tells me that you probably don't ski like this...
If you lead with your inside ski it doesn't take much for that inside ski to diverge just enough to be on a good path.
post #116 of 131
Thread Starter 
Quote:
Originally Posted by Max_501
If you lead with your inside ski it doesn't take more for that inside ski to diverge just enough to be on a good path.
Actually you might be able to help me with this. Could you use the picture that you posted in the PMTS Race Camp thread you started and edit it in photoshop or a paintshop program of some sort by adding two vectors to it? On running down each ski from the binding/boot to the tip of the ski and continuing out about a ski length in front of you. The lines should be parallel with the direction that the skis are pointed in.

Later

GREG
post #117 of 131
Quote:
Originally Posted by HeluvaSkier
Actually you might be able to help me with this. Could you use the picture that you posted in the PMTS Race Camp thread you started and edit it in photoshop or a paintshop program of some sort by adding two vectors to it? On running down each ski from the binding/boot to the tip of the ski and continuing out about a ski length in front of you. The lines should be parallel with the direction that the skis are pointed in.
If you are talking about the picture of the brushies I'd hate to see where my skis are pointing. I was in full survival mode whenever I dropped into the course.
post #118 of 131
As I mentioned earlier, I think 'redirect' is something we can accomplish a number of ways aside from the rotational method. That said... the images posted might, or might not demonstrate what each person prefers to see.

My own *guess* is that the skier (in post by SSH) has more weight on the middle/back of the Outside-Ski in frame 9 - so it is traveling straighter, while the Inside-Ski has more weight on the front/tip causing it to turn more rapidly - delivering the divergence seen. (Kinda what Slatz said I think)

Just because the ski is very bent in a still image doesn't mean it's effectively delivering centripetal force to turn the skier. We've all seen slow-motion shots of downhill'er skis where the ski-tips catch & skitter wildly about while the true path of the skier is determined by the ski section directly underfoot.

A downside of still images (even montages) is that we can't see accelerations so they leave us with the impression of constant linear (or rotational) speed. We can't see if a sudden 'twist' occured on a given ski between frames, and we can't see CM movement that would point to a pressure change underfoot.

In a still shot, the two-footed nature of skiing mucks up our ability to say just how much pressure is on either foot at a given moment in the image. Sudden (unseen) extension can transfer pressure instantly - before the CM moves enough to be noticed in the next frame.

And a ski does *not* always release its existing curvature (bend) just because we *lighten* it a bit for a brief moment. It will stay in the same approximate bend until it moves forward enough to (gradually) establish a new, less bent track. On the other hand, reducing the tilt-angle of a ski will have an immediately visible effect on a firm surface. The biggest difficulty with 2D images is the telephoto effect - the shrinking of perspective.

It would be great if someone could find a "high-speed" video clip (played in Slo-Mo) of an SL turn and post the link to that. From that, we could better detect what's really happening. (Though only in the turn demo'ed - not as a general rule)

.ma
post #119 of 131
Quote:
Originally Posted by Max_501
If you lead with your inside ski it doesn't take much for that inside ski to diverge just enough to be on a good path.
Some German's allready call him:"Herr Direktor"; some Ladies:"Mistahh...", well although I have no time to choose a name, I agree!

there are some other discussions in the energy club, Max
http://forums.epicski.com/showthread...703#post522703
post #120 of 131
Quote:
Originally Posted by Max_501
If you lead with your inside ski it doesn't take much for that inside ski to diverge just enough to be on a good path.
The leading I'm talking about here is regarding the timing of the tipping. Tip the inside ski first and the outside ski follows (didn't want folks to think I was referring to tip lead).
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