2 footed release - turning forces?

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2 footed release - turning forces?

Postby hacker » Sat Feb 02, 2008 11:52 pm

Hi

I have read a bit about PMTS(the 2 expert skier books and the essentials book) now and have been reading this forum for a while.

One point remains a mystery to me and it seems like it is quite important. I'm sorry if this question has been answered already, but I did a search on the forum and could not find it.

My question:
It has been stated a number of times in this forum that in the two footed release you turn the ski tips down the hill by:
In PMTS this is accomplished through letting gravity and balance pull the skis to the falline. In PMTS there is no twist, pivot or steering involved, no unintended energy from the body is used. Only relaxing is used to begin the action. Just the actions of relaxing to tip and flattening of the feet.


Can someone explain how "gravity and balance pull the skis into the falline".
A simple force diagram would help. What are the rotational forces turning the skier/skis?
I don't believe gravity by itself will 'turn' the skis as gravity will be pulling on all of the skis and the skier.
I am thinking some opposing forces are in the mix?
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Re: 2 footed release - turning forces?

Postby MonsterMan » Sun Feb 03, 2008 12:16 am

G'day hacker;

look at the centre of mass over the base of support. Example: my wife's new skis have the bindings mounted 810mm back from the widest point at the tips of the skis; this is only 605mm forward from the widest point at the tail.

I propose that most skis have the centre of the foot mounted further back than a point equidistant between forward most point of contact and rearward most point of contact.

Now take a two foooted release:

There is more ski foward of the centre of the foot. (edited 4 Feb, original post was rushed and I had it backwards:Geoff)

This creates a moment due to gravity that rotates the ski tips downhill with respect to the ski tails.

Viola! release and wait until gravity does the work!

regards

Geoff

Geoff
Last edited by MonsterMan on Sun Feb 03, 2008 3:45 pm, edited 2 times in total.
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Re: 2 footed release - turning forces?

Postby Tommi » Sun Feb 03, 2008 12:28 am

Here's my 2 cents worth (before fall line):
- front/aft balance ( a beginner with backseat position will be sliding backwards)
- letting skis flatten causes inertia from the leg movement (passive rotational force)
- when letting counteraction unwind the upper body is not following the turning, thus there is not much turning force needed

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Re: 2 footed release - turning forces?

Postby carver_hk » Sun Feb 03, 2008 7:12 am

I ll add one more line to the original question below:

In linked TFR, right after the transition, should both skis be flat, on uphill edges(like the individual TFR before moving) or downhill edges(like carving after engagement)?

I ask in this thread because the forces that bring the ski tips downhill might not be the same.

Thanks for sharing your insight. :D
I love line graphics :)
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Re: 2 footed release - turning forces?

Postby h.harb » Sun Feb 03, 2008 10:15 am

That is actually true, in the stationary Two Footed Release, leg relaxation and foot tipping to flatten the skis, allows the legs to move over the skis, into the new edge angles. Inertia developes when the feet flatten the skis so the legs can move from their starting angles to flat. The doesn‘t offer a great deal of energy. It is for this reason in connected turns that tipping to the very end of the turn, until just before release; is so critical . The bigger the ski angles and leg angles you develop at the end, the increased travel range you have through the de-angling movement or release. Keeping the legs bent through this movement is critical and staying bent through the transition is often lost to extension. Extension is the killer of good skiing. .

The PMTS approach develops more leg bending to achieve more angle at the end of turns, is not only good skiing, but to PMTS skiers it’s “the system“, as we don‘t initiate leg twisting, rotary or steering to redirection the skis. Opposite of what the PSIA approach focuses on.

The other factor is that as you move in connected turns, you can relax more and commit more because of momentum developed, which means you don’t have to be as precise standing directly over the skis, as you do from the stationary release.

The stationary release is an eye opener, as it requires complete balance over the skis, not allowing for any pushing of the CG. Pushing of the CG comes from extension movements and it pushes the GC out of balance. There is no extension, especially no up extension (to create pressure) in good skiing, if you look at skiing this way and use only leg lengthening (to the side, at an angle to the slope) to keep contact, you will develop into a much more balanced skier and a smoother skier.

Skiers often think that they are in balance just because they can stand up from turn to turn. This is likely due to understanding from instruction given them by unknowing instructors. Take away the momentum and you will quickly discover you need a different standard or real balance, as I call it. Once a skier stops pushing their CG around, into turns or up; instead lets it move through transition; they begin to realize the efficiency of relaxation, lower body, ankle and foot control.

When they do, they become very different skiers. I can see this level of skier from a 100 yards down the slope, as it offers a totally different image. Skiers like the PSIA and Epic followers don’t understand this and never will, as they are stuck with leg rotation and leg extension habits and directives. Their arguments in support of these movements only serve to deepen their dependency on these movements and it demonstrates their limitations. What they don’t realize is they don’t make theses movements by choice, after awhile, they become dependant on this form of skiing and they can’t shed. This is a very limited way to ski and it lack the ability for this skier to become versatile. In an attempt to protect there way of skiing and the limitations they deal with, PSIA instructors cover up their deficiencies, instead of facing them head on. They argue that, “this is the method for all good skiing“. It’s not the method that produces good skiing this is obvious for anyone with a eye for skiing, and it’s definitely not any part of good skiing.

If you focus on the two footed release in the manner described in my books and on the forum, you will achieve versatile skiing, good skiing, to expert skiing.
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Re: 2 footed release - turning forces?

Postby hacker » Mon Feb 04, 2008 5:54 pm

Sorry I am still failing to get a mental picture of the forces turning the skis

From responses so far I have gathered:
1. the skier is not turned much because the body is already counteracted from the previous turn and is so facing down the hill (so lets not worry about the skier)
2. letting skis flatten causes passive rotational forces because the thighs have to move
(comment: this is not gravity)
3. bindings are generally mounted further back on the ski. This means more ski forward of the skier which creates a momet due to gravity.
( comment: sorry do no follow this, if there was no atmosphere and you droped a object from a plane of lopsided wieght would it end up with heaviest part below the lighter part: answer = no (I think). With speeds we are talking about atmospheric resistance is not very relevant. Note: but snow resistence would be. Furthermore I think the weight of the ski is negliable to the weight of the skier)

So far I still can't see gravity doing much by itself - may unequal snow resistance fore/aft is doing something ?

As a said a force diagram would be good.
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Re: 2 footed release - turning forces?

Postby Max_501 » Mon Feb 04, 2008 7:54 pm

A force diagram or an in depth physics explanation doesn't make the two footed release any easier to perform. This is a drill that can only be performed when the skier discards all active rotary input.

If a skier is interested in learning a two footed release the best bet is to follow the instructions in book 2 exactly as HH has written them. Practice for a while and then get some video and post it for further MA.

Its a movement pattern that yields great results but is surprisingly tricky to get right.
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Re: 2 footed release - turning forces?

Postby h.harb » Mon Feb 04, 2008 9:23 pm

I have to agree with Max, a force diagram doesn’t make a better skier. If there were no gravity, would your two footed release, move the skis? No. The two footed release doesn’t work on the flats and it's much more difficult, on flat slopes, so gravity has a much bigger impact on your skiing then you give it credit .

Rather than striving to manufacturer a force diagram, why don't you go out and manufacture some two footed releases on different slope steepnesses and then try it on a totally flat surface in the parkign lot. Don't try it in the Loveland Parking because it has a slope. You might find the answers to your questions and learn more about your movements and skiing than looking at an equation and vectors on paper!
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Re: 2 footed release - turning forces?

Postby nugget » Tue Feb 05, 2008 12:22 am

Hacker
u mentioned the book "Expert Skier 2". It does come with a DVD and if u can access that then it gives a visual demo of said release (TFR = two footed release).
A video picture is worth a thousand force vector diagrams. There are some pitfalls to avoid when releasing and they are covered thoroughly in the book as well.
Enjoy the practise.
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Re: 2 footed release - turning forces?

Postby BobH » Tue Feb 05, 2008 2:22 pm

If my focus is on carving the High C, is the TFR excercise in book two the proper drill to concentrate on?
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Re: 2 footed release - turning forces?

Postby Icanski » Tue Feb 05, 2008 6:20 pm

IMHO the TFR helps everything you do, including carving in high-C; it helps balance, foot control of the tipping, lots of things.
One thing you can do,too is look at your tracks. the tips will leave a mark where they've slid down towards the fall line, but if you look where your tails started, you will see the snow pushed/moved down the hill from there as if the tails were the center point. IOW, the skis moved downhill from the tail. If you see the snow moved uphill from the tail, then you are pivoting at the boots, or around there. Tracks are a very effective tool for looking at what's happened. Good luck and have fun.
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Re: 2 footed release - turning forces?

Postby NoCleverName » Tue Feb 05, 2008 6:42 pm

I can see the wisdom of the TFR from another angle. I've been trying to fix up a few things and have gained a significant appreciation for the transition (which I know still isn't right) and in doing so finding yet more meaning in HH's words --- even if I thought I already knew what he was saying.

I can now see that going straight for the OFR (without insight) can lead to significant opportunities for push-off. I discovered this just by standing there and trying to smoothly "lighten" a ski. I discovered that if you try to just "lighten" by the obvious approach of more or less flexing or raising the leg, you in fact have to make a preparatory gross movement to balance on the new stance leg before actually trying to lighten.

If, on the other hand, you lighten by simply raising the heel (making the toe a pivot point) there is no need to prebalance on the stance leg!.

It's quite the different and subtle feeling as the weight and balance smoothly transitions during a heel lift versus the almost hidden but massive balance shift using any other technique.

So, the TFR avoids the opportunities for push-off presented by the OFR and at least opens the gate to properly executing the follow-on moves. But, it seems you really have to be aware when you graduate to the OFR.

I'm starting to see the transition as the one part of skiing that if not done right creates pretty much every downstream problem there is. Now, if I can just learn it without killing myself. I'm holding it and checking it for so long those narrow NE trails are certainly becoming a lot less roomy than normal!
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Re: 2 footed release - turning forces?

Postby Icanski » Wed Feb 06, 2008 7:12 pm

I hear you on the narrow trails. I remember when I was first learing PMTS, I seemed to take up a lot of real estate, too. Now, I love to go to a narrow run and see how many TFR I can do in a row, right down the fall line, then I'll go back and start with the other turn on the same path and see if I can get figure 8's all the way down. Maybe I have too much time on my hands?????? :roll:
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Re: 2 footed release - turning forces?

Postby Hacski » Fri Feb 08, 2008 5:50 am

If the 2FR isn't clicking in what might be the main thing to concentrate on correcting, particularly if one direction is a lot weaker than the other?
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Re: 2 footed release - turning forces?

Postby Tommi » Fri Feb 08, 2008 6:27 am

I'd say that it's practically impossible to guess anything without seeing you make the TFR drill. Post a video, then the experts here probably can help you.

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