Feet pullback physics

[Tommi]

I would appreciate a discription of the pullback mechanics. How is it possible to pull the feet back and at the same time maintain flexing. Because deep flexion actually pushes you easily in the back seat..

I have struggled with this. If I really (no, REALLY) pull the feet forcefully back, I cant avoid extending (like in the pullback exercise). Maybe I have too stiff boot settings (I have the boosters) or my cuff/ramp angles are wrong? I tried to set the cuffs more forward today and it felt actually very much better.

Have I misunderstood (once again, keep cool HH ) the timing or something here. I think pullback can be done forcefully at the same time when letting the stance leg extend AFTER transition.

HELP!

T2

[milesb]

Sounds like you have it right. About a month ago Harald posted something about this, do a search (someone help?). Just think about the position you would be in if you DIDN'T pull back while flexing deeply, the skis would shoot out from underneath you. But you are correct in thinking that the important time to pull back hard is as the new turn starts. It's much easier if you have decent momentum from the previous turn to keep your upper body moving forwards BTW.

[Ken]

The time to pull both feet back is when they're light. This is in the transition between turns or when cresting over a mogul (also a transition between turns). At this point both legs are equally flexed.

The time to pull the free (inside) foot back is continuously, from the beginning of the new turn to the end of it. Don't stop tipping more (and more and more), and don't stop pulling back.

[h.harb]

Tommi since you bring up the subject, are you trying to incorporate and layover different movements onto your present habits. Before you can change your old habits; you have to completely understand what those movements are and what they are doing to you.

Your present movements, or at least what I see from your posted video clips, begin with an outside leg extension, do you understand completely what this is and what it does? Do you see it when you watch your own video? An outside leg extension is not a release!!!.

It?s actually engaging the ski more. So it delays the transition of the body into the new turn. A leg extension raises the body, makes the leg long, and moves the Cg uphill. After the body is moved uphill toward the uphill ski, the uphill leg will become the stance leg, but this has done little to move the body into the new turn to create new angles.

Since the body has been moved uphill, it needs a new direction. The new direction comes from the uphill leg extension , which pushes the body into the new turn or toward the center of the new arc. This is what is happening presently in the turns you posted.

Tommi comment:

How is it possible to pull the feet back and at the same time maintain flexing.

The reason I posted the above description of what you are doing, is because, you might be confused by your movements.

For example; we do not maintain flexing in skiing. Flexing is a very short duration movement. It's a change in leg length, it's not supposed to be maintained.

Flexing should be combined with tipping. Flexing first, to reduce the pressure on the stance ski, at the end of the arc, and then tipping occurs as the flexing leg bends and the hips move lower. Watch any of the WC video on the internet, this happens in every slalom turn.

Pulling back comes in as the skis are tipping toward the new edges. IF, (big IF), you get float because you developed or used energy from the previous turn, you don?t have to pull back during flexing and tipping. The float will hold you until the skis are engaged on the new edges.

If you did not get energy out of the last arc; you have to work harder with pull back because you?re flexing move can put you in the back seat and the skis will run forward.

Pullback should happen before the skis are pressured in the new arc. You can't pull back if you are extending. Extending is an essentric contraction of the quadriceps muscles and flexing is a concentric contraction of the hamstring muscles. So they can not happen at the same time. This means if you have started extending to get out of the turn (even a little) you can't possibly pull the feet back.

[h.harb]

Just for accuracy?s sake: pull back comes under the discussion of biomechanics. Physics describes the forces, vectors and momentum developed from movements on skis that cause results we don't want. That's why we need to intervene with accurate movements.

Skiing , economically, smoothly and with balance, is just managing and redirecting momentum correctly.

[Tommi]

HH said:

Your present movements, or at least what I see from your posted video clips, begin with an outside leg extension, do you understand completely what this is and what it does? Do you see it when you watch your own video?

Unfortunately I do see the up-move and the back seat, and I've worked the last days trying to figure out how to trigger a change. It's definitely a lot easier to get some flex in transitions from left to right, as you can see. In turns right-left I always jump, even if I try to flex. It becomes like a-microhop-and-then-flex.

Tommi comment:Quote:
How is it possible to pull the feet back and at the same time maintain flexing.

English is a foreign language to me... I meant, 'How is it possible to pull the feet back and flex at the same time'. This is what I meant with the physics. If we freeze the moment a perfect skier flexes (1 microsecond) , he/she can't have skis pulled back (static geometry), the geometry won't allow or he/she has really flexible boots. But if there is rebound from a previous turn, his/her body inertia could be directed so that the result is the same as with skis pulled back. Isn't it body geometry, movement and inertia (ok, biomechanics was what I meant)?

If I have understood right, the key moment when the wrong movement really begins to materialize in my skiing is the flexion/sitting down in the end of the carve, and then extending to get the release? So I should try to reverse this, keeping the stance leg extended and then without hesitation just letting go.. easy to say but.. I can make the power release drills etc but..

Back to work.. when the resort opens again. I'll sort this out!

Here's a flexing video from yesterday. BTW I noted that now the angles look like mine, I had wrong settings in the video capture 4/3 instead of 16/9. The difference is quite visible. And here, again, in spite of trying to flex like hell, in the 2nd last transition there's a visible up extension before the flex..

Me trying to flex:
http://www.tupusurf.net/videos/tryflexing.wmv

The same tries to get those feet back:
http://www.tupusurf.net/videos/tryfwd.wmv

Sad, I know!

HH, how about some ramp/cuff trials? Would those help? I tried some cuffs fwd but unfortunately I don't have video. Felt better.

T2

[h.harb]

This latest video is a huge improvement, now do the same as you ski on steeper slopes, but don't ski faster, control your speed by finishing the arc.

Tommi

If I have understood right, the key moment when the wrong movement really begins to materialize in my skiing is the flexion/sitting down in the end of the carve, and then extending to get the release? So I should try to reverse this, keeping the stance leg extended and then without hesitation just letting go.

This is a great realization, more skiers should focus on this statement and analyze what they do in all skiing situations.
Yes, this is exactly on target. Practice the power release slowly and make turns slowly, until you feel the similar movements and results. .

[leopold bloom]

Hello T2

With your perseverance and focus it is only a matter of time before the dreaded up move is history.

Flex to release is the mechanical prescription for your malady.

Being a firm believer in the curative powers of the mind, I am inclined to say that the mental prescription should be, "Release to flex".

Releasing the muscles that support the pressure you are developing through the turn will deliver the flex. Like so many things in skiing, it is virtually free. For this to work, you must be resisting some pressure above and beyond mere gravity at the point of release.

No question,you will know it when you get it. I can still remember the first time I got a "dynamic release" without the body-crossing-skis-downhill-faceplant that accompanied many of my early efforts.

It felt like the hand of God rested briefly on my tail bone and threw me perfectly into the next turn.

Through theological deduction, based on the omnipotence and omnipresence of the Creator, I concluded that this benevolent force would carry me anywhere through any kind of snow condition with minimal effort on my part. Theology was right.

Good luck Tommi, in finding your leap of faith, and a Merry Christmas to all.

- Leo

[Gene P]

Tommi,
I know the struggle of the Flex well. No need to wait until you are next on the Mountain. Try the dryland exercise Jay showed us in the bar at the Hintertuxerhof: lean against a wall or door post in a position with one leg almost fully extended as if illustrating a high speed carve; then gradually try release / flex to a position as if you were about to start a new turn [obviously you will only be able to get to the "transition position"]. Do this withouth ANY up movement from the stance leg and you will have cracked it! Keep at it....once you get it , you will never go back!

Happy Christmas.
Gene

[Tommi]

Hi Leo and Gene,

Thanks for your support.

Leo, that's a great thought - release to flex.

Gene, I remember the practice in the bar, so much fun and Jay almost dropped to the floor from his almost impossible angles (even with very few beers!!).

If the lurkers find my flex struggle surprising even after a campful of practise, I can say it's easy to lose the most important movements.. when they are not yet fully changed to routine. I think the only mistake I made in my practise this year was the 'forcing to get the angles'. I flexed, but AFTER I had pushed against the turning forces and tried to float.

Mental training - very familiar to me - I used it very successfully all the time during my aerobatics career - actually before every flight. It's really efficient. I have to take mental imaging into use in skiing also, before every run, before the first turn.

Merry Christmas everyone!

T2

[Ken]

For me, I need the thought of pulling my knees up toward my chest to do the flex & release. There are other ways to express this, and some other expression of this movement might be more clear for a different person. My movement that feels like a great, deep flex actually looks minor when seen on video.

[Tommi]

I've managed to reformat the picture dimensions in the 'another video' thread videos to the 'normal' ratio so that the image is not stretched.

T2

[vseh]

Since the talk is of physics and pullback, I have a question.
I've noted that effective tipping is much harder without effective pullback.
Without good pullback I tend to smear my turns.
Why is it so?

[tdk6]

Great skiing Tommi. BTW, I cannot see much difference in both videos. What are the major changes in your own opinion.

[quest]

....An outside leg extension is not a release!!!.

It?s actually engaging the ski more. So it delays the transition of the body into the new turn. A leg extension raises the body, makes the leg long, and moves the Cg uphill. After the body is moved uphill toward the uphill ski, the uphill leg will become the stance leg, but this has done little to move the body into the new turn to create new angles.

Since the body has been moved uphill, it needs a new direction. The new direction comes from the uphill leg extension , which pushes the body into the new turn or toward the center of the new arc. This is what is happening presently in the turns you posted. ....

For example; we do not maintain flexing in skiing. Flexing is a very short duration movement. It's a change in leg length, it's not supposed to be maintained.

Flexing should be combined with tipping. Flexing first, to reduce the pressure on the stance ski, at the end of the arc, and then tipping occurs as the flexing leg bends and the hips move lower. Watch any of the WC video on the internet, this happens in every slalom turn. ....

I think I understand most of the above. But after flexing and tipping, and after the new stance ski is onto the new edge, do we do a little bit of 'lateral extension' (I dread to use the word 'extension') to engage the ski edge? Otherwise with flexing on each turn, we are getting lower and lower.