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What's the Diff? - Page 12

post #331 of 341
Quote:
Originally Posted by Rick View Post

 

I'd have to agree.  If the skis are not weighted, such as in a strongly retracted transition, tipping the ankles does nothing to jump start the turning, force building process.  It can't begin until ski to snow contact and engagement reestablish, at which point the CM is has generally already moved inside the feet, and is prepared for the big force spike about to happen as the already tipped edge touches back down and engages strongly.  When maintaining pressure all the way through the transition engagement happens more smoothly, and turn forces grow more gradually.  

 

  Nope. Nothing at all. Note that in the second video the coach is talking about fore/aft flexion, which is ancillary...the important part is to just watch the tipping movement of the feet in both.

 

   

 

   

 

   zenny

post #332 of 341

 Especially with a flexed transition, if you do not initiate edging with LTE tipping the tendency will be for the foot to rotate outwardly (which produces more of a steered effect into the direction of the turn rather than an edged one). Unless it is weighted...if it is weighted, initiating at the hip will instead cause the ankle to be "forced" into tipping and create tension around the subtalar joint which in turn partially locks it and makes further tipping much more difficult. Note images B and C below...

 

  

 

  Ankle tipping moves the leg, upper and lower (and foot) as a unit.

 

  Edit: This is easy to replicate in your living room with ski boots on or out on the slopes. This is fairly basic stuff.

 

  zenny


Edited by zentune - 4/7/15 at 6:43am
post #333 of 341

 One last thing and then I have to go to work....one of the things I like about the "get over it" drill is that the skier pays attention to the inside ski even thought the emPHAsis is on the outside...you can see proper foot/femur alignment of the lifted ski if you watch closely. If she hadn't tipped the ankle and instead rotated the femur first the lifted ski would rotate in the opposite direction (into the turn direction).

 

   

 

  zenny

post #334 of 341
In your diagram above though the pelvis has remained in the same position. That's not the same scenario as the Italian vid advocating the body going into the turn. The leg shafts would essentially be tilted downhill.
One can combine the two movements.

The ankle flexion video. Ok, if i were to make a vid focusing only on increasing edge angle, call it "edging", we'd be missing half the picture. Just as important is reducing edge angle and releasing. Similar to the ankle flexion video. Ignored is where the ankle opens.

So, is one supposed to keep their ankles flexed at all times? Pressing hard into the boot tongues? That's the implication of the vid. But no.

It's similar to the interpretation that French racers were sitting back on their tales due to snapshots taken at the moment they were back.

See this article by Stu Campbell, 2002, Ailing From Avalement
Link brings you to 2nd page of article.
post #335 of 341
The drawing is not mine but tdk6's and it represents a static demo, thus no pelvic movement. The ankle flex vid was only posted to show ankle tipping--as I said the fore/aft commentary is beside the point. :-)

zenny
post #336 of 341
Thread Starter 

Originally Posted by JESINSTR View Post

BTS and Ghost.  Let me throw this at you just as food for thought. 

 

Consider a tennis ball on a string and we begin to swing it around our head.

 

Imagine if you will, that the ball out at the end of the string represents our CoM and the point at where our fingers are pinching the string is our edges. 

 

Propulsion for the ball (source for Mr. C) comes from the muscles in our fingers/wrist etc.  Propulsion for our skis comes from gravity plus slope.

 

The significant difference between each scenario is all about the connector.  One is a piece of string whose only property is tensile strength whereas in skiing with have an assortment of joints, ligaments and muscles between our source of propulsion and the CoM. 

 

I think (hopefully this is BTS's point of view) it makes sense that we control forces with what is available closest to the source of the force. Like you guys said it is a lot of fun just to let that CoM fly but as you also said, not for teaching's sake and probably not for efficiency as well.

 

Again as I have said in other posts, this is not about Balance/Imbalance because that word has sooooo many definitions and applications when it comes to skiing.  It can only lead to non productive interactions....it is in the end about progressively controlling force. 

 

Quote:

Originally Posted by borntoski683 View Post


I think that entering a turn unbalanced is the same as suddenly having the string go slack somehow in your tennis ball example, and then waiting to generate tension again. In skiing the edges provide what the string provides the tennis ball. Centripetal force. So if you start out unbalanced some of that will be compromised. it's like losing tension in the ball string. The force doesn't even exist unless you ensure your CoM is in the right place relative to your BoS so that those forces will be created. This is a balance skill

BTS Sorry I am late responding to this.

 

I totally understand where you come from on this.  But I would submit that the string on the ball going slack, means the ball (mass) is returning to an inertial path of travel (assuming there is momentum)  Likewise, in terms of skiing, once we release from the centripetal force we are generating, our mass returns to an inertial path of travel.  As this happens, Our sense of balance now needs to deal with balance against gravity vs the previous requirement to balance against centripetal force. I know Rick calls this "Imbalance" and from a physics definition perspective he is right but from a student's ability to comprehend I wouldn't go there.  

 

In skiing, as long as we are going in and out of circular travel there will be two forces against which we have to balance to keep from falling down.  Gravity is the one that our body is designed to deal with, centripetal is the one we have to learn.  And when it comes to those intermediates,  It is getting them to STOP using gravitational (inertial) balance reactions when trying to build a turn. 

post #337 of 341
Yes jesinstr, loss of crentripetal forces results in loss of turning, ie going straight, and that is what the ball with the suddenly slack line would do also.

One thing to consider in skiing is that you don't have to totally release all at once to straight travel. You can progressively release so that balance progressively changes its blend of Mr C and Mr G until at neutral with flat edges there is no more Mr C.
post #338 of 341
No need to fly off on a tangent?? :-)

zenny
post #339 of 341

Since we have Mr. G pulling us down, and Mr. C pushing us toward the centre, we might as well give due credit to Mr. N (normal force).

We can let go of all of Mr. C, and we can stop resisting Mr G too...or not, depending on what we do with Mr. N. 

Mr. N is the trickiest Mr. to manage, as good management of Mr. N is crucial to (nearly) continuous edge engagement.

post #340 of 341
Quote:
Originally Posted by Ghost View Post
 

Since we have Mr. G pulling us down, and Mr. C pushing us toward the centre, we might as well give due credit to Mr. N (normal force).

We can let go of all of Mr. C, and we can stop resisting Mr G too...or not, depending on what we do with Mr. N. 

Mr. N is the trickiest Mr. to manage, as good management of Mr. N is crucial to (nearly) continuous edge engagement.

 

There seems to be a lot of discussion of people I have never heard of as well as that they are being followed by these people whenever they are skiing and apparently being pulled and pushed around. I would recommend going to the ski patrol to complain.

post #341 of 341

Well Mr. C is completely in our control, and Mr. N. is within our control provided we stay within a limited distance range of the surface and average out over time to equal the normal component of Mr. G.  That Mr. G never stops pulling though :nono:.  

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