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Accelerating out of a turn - Page 8

post #211 of 235
Quote:
Originally Posted by majortato View Post

..................

Losing energy elsewhere is not really a concern...that ski will bend no matter what you do.  It's inevitable when you turn, and therefore moot.  There's nothing you can do to prevent the ski from bending.  I..........

.........

In the end, it's all about what you can do to reduce the amount of energy lost. 

So isn't it just as inevitable that the energy stored in the ski by bending it will be released (unless the ski remains bent of course)? When people talk of rebound in this context it must be a matter of releasing that energy suddenly and at an advantageous moment. How and when does this get translated into forward (direction of travel) movement?

post #212 of 235
i think majortatos feelings are that if there is some stored energy present in the skis (and weve acknowledged that there is...how much may still be up in the air) and we use this to aid us in retraction/extension movments (cross under/over) it will then aid us in projecting our com's towards the inside of the new turn that much earlier. correct me if i misinterpereted, major;)

therfore taking a shorter route...
zenny
post #213 of 235
Quote:
Originally Posted by majortato View Post

So you agree that this rebound (if used properly) helps with a certain movement..and that movement can allow us to be faster. 

Admitting? That is what I said before this was even started and now you seem to think that you just made it up. But I did not say that we become faster because of it.

If you had a bar of C4 explode under your ski just before retraction it would be fast as ..., but will you become faster? No, you will land way uphill.

 

When it comes down to it, that's all I was really arguing.  

Really! I remember you arguing a lot of other things as well.

 

Losing energy elsewhere is not really a concern...that ski will bend no matter what you do.  It's inevitable when you turn, and therefore moot.  There's nothing you can do to prevent the ski from bending. 

Well is sure sounded like you said you have to push on it to bend it and others said it was enough to stand on it.

It's like talking about extra friction forces when you turn.....if you want to turn, you're going to increase frictional forces.  Like I said before, the whole system is a net loss.  Only a percentage of total input energy (gravity/muscle movements) can be converted into positive outcome (turning, increased speed, balance, etc.).  Conservation of energy is useful when applying physics theory using mathematics...in the real world, applying this idea doesn't do much because so much energy is dissipated through heat/friction (still conserved..but not in any meaningful way).

Funny, if the bending energy in the ski is lost and it is as big as you claim, the ski would be melting ROTF.gif 

The ski is pretty much the only thing that is elastic here, snow, wind and muscles are not.

Seriously though, I think a number of arguments have been presented that you don´t become faster because of camber spring action, but you have chosen to only attack a few and not address the ones you cannot argue against, whilst showing no holding arguments of why it would be faster.

 

In the end, it's all about what you can do to reduce the amount of energy lost. 

It is about the time. Highly correlated but not quite the same.

post #214 of 235
Quote:
But I did not say that we become faster because of it.

You said it helps with the retraction move.  The retraction move is something we want to do is it not?  So if it helps in some way...does this not make us "faster"?  I'm not talking strictly about speed when I say faster....I'm talking about being faster overall.  Person A could travel at a higher speed than person B, but person B takes a shorter line and ends up "faster" through a race course.

 

Quote:
Really! I remember you arguing a lot of other things as well.

I did argue a lot of things...it's all tangential off the original point.  A lot of it is re-iterating in different terms.  I'm not gonna turn this into a 'he said she said' debate.

 

Quote:
Well is sure sounded like you said you have to push on it to bend it and others said it was enough to stand on it.

I never said you had to push on it to bend it while skiing.  We talked about pushing on it at home to bend the ski and see how springy it is.  As I have clarified multiple times...This is a semantics thing.  I was referring to "push" was to describe the feeling of putting pressure on the skis to turn....it can also be described as "bracing against the forces". 

 

Quote:
Funny, if the bending energy in the ski is lost and it is as big as you claim, the ski would be melting

I never claimed the energy was that massive..you put words in my mouth.  You made the assumption that I was arguing the energy it provided did all the work to turn and accelerate a 180lb skier across the hill.  I never thought this, and if you read into it like that, it's another case of misunderstanding what I was trying to portray.

 

Quote:
Seriously though, I think a number of arguments have been presented that you don´t become faster because of camber spring action,

If by a number, you mean the ONE argument that the energy is negligible and in the wrong direction.  The direction part, I have pointed out number of times is actually in a direction that is useful.  And the energy amount part, I have also pointed out, does not need to be huge for it to have an effect.

 

Quote:
you have chosen to only attack a few and not address the ones you cannot argue against, whilst showing no holding arguments of why it would be faster.

 

Except I did for the most part and ignored certain aspects I felt not important or was dragging the conversation away from what's important.  I do not wish to repeat myself again.  A lot of things I talked about were not addressed by you either.

 

Jamt,  I'm here to have an intelligent discussion about skiing mechanics and physics.  It can lead to thinking about things more clearly or opening up new ideas.  Over the course of this, I have evolved my vision of ski physics and mechanics.  I have moved away from the idea that the ski rebound increases speed, rather it aids in our turns in other ways that can result in us going faster.  Not sure if you caught that or if you're still holding onto the words I wrote in my first post and trying to argue against it.

 

Perhaps I'm reading into this wrong, but your previous post sounds like you're here to "win an internet argument" and trying to sound superior by basically claiming my arguments are ridiculous (throwing around over-the-top statements of using C4 or melting skis).  Your post was more focused on belittling the things I said rather than talking about the topic at hand.  If you want to have a debate..I'm all open.  If you want to turn this into a 14 yr old "bash at those who disagree with you" thread...I don't have the time.  It's hard to detect tone on the internet, so I'm sorry if I'm mistaken.

post #215 of 235
remember majortato, who here have helped "evolve" your thinking...Skidude, perhaps me to a degree, AND Jamt! i for one want to see a little more if what youve learned. if i wasnt on my crappy phone, id post the montages of bode and ted Jasp posted in the recent thread regarding "leverage"( this is not its name...should be easy to find tho).seriously, lets get some visuals going! teds is a crossover, bodes an under(with an nice aft emphasis;) ) let us discuss what the right time to release really is...or isnt:)

zenny
post #216 of 235

Major, I find these discussions interesting because it makes me think of things in different ways, and I´m sorry if I struck a nerve with my latest post, but some of if was just an attempt to be a bit funny, nothing personal. However, if a little added energy is good, then more added energy should be even better right, but perhaps C4 was a bit too exaggerated :-) 

Similary, if a little spring is good, then a strong spring should be even better right?

 

Which is faster in the course, having something push the skis uphill (spring rebound) or pulling the skis up. Think about it.

 

Regarding "Winning an internet argument" you kind of got me started there with "so you agree" when it was something I have said for a long time. It´s not about winning, I´m anonymous here so I have no honor to defend. But I really want the "truth" to prevail. I really want to understand these things, and if I can learn something new that´s all good, but as long as I think something is not right I will continue (at least until I give up)

You say that you evolved your thinking and that is good, but it was a bit difficult for me to understand. It is quite difficult to keep track of these threads that easily turn into train wrecks.

post #217 of 235
Quote:
I´m sorry if I struck a nerve with my latest post, but some of if was just an attempt to be a bit funny, nothing personal.

No worries..like I said, tone is tough on a forum.  It's tough to tell sometimes when someone is being sarcastic and humorous or otherwise.  Thanks for clearing it up.

 

 

Quote:
Similary, if a little spring is good, then a strong spring should be even better right?

 

To an extent.  Too strong of a "spring" and it becomes harder to bend the ski delaying the turn initiation.  Just like everything else in life, always in moderation.

 

Quote:
Which is faster in the course, having something push the skis uphill (spring rebound) or pulling the skis up. Think about it.

what part "pulls" the skis uphill?  Leg movements?  Because I think the legs are trying to be passive at this point (or rather trying to relieve the pressure on the skis).  Also I think all movements are downhill...just a question of more or less.  But for a moment suppose it's a pull....then I say "why not both?"  

 

 

Quote:
It is quite difficult to keep track of these threads that easily turn into train wrecks.

no argument there. ;-)

post #218 of 235
Quote:
Originally Posted by majortato View Post

No worries..like I said, tone is tough on a forum.  It's tough to tell sometimes when someone is being sarcastic and humorous or otherwise.  Thanks for clearing it up.

Forums can be tough, indeed! When one changes one's "tune" a few times in one forum people understandably get confused.

 

 

To an extent.  Too strong of a "spring" and it becomes harder to bend the ski delaying the turn initiation.  Just like everything else in life, always in moderation.

How strong is too strong? Care to elaborate? I know plenty of racers with stiffer (longitudinally) skis than mine who initiate just fine...

what part "pulls" the skis uphill?  Leg movements?  Because I think the legs are trying to be passive at this point (or rather trying to relieve the pressure on the skis).  Also I think all movements are downhill...just a question of more or less.  But for a moment suppose it's a pull....then I say "why not both?"  

Actually, not ALL movements ARE downhill. Do you have a guess as to what I am referring to? 

no argument there. ;-)

   zenny


Edited by zentune - 2/21/13 at 8:24pm
post #219 of 235
Quote:
How strong is too strong? Care to elaborate? I know plenty of racers with stiffer (longitudinally) skis than mine who initiate just fine...

 

Each person is different.  For a beginner/intermediate or a lightweight, it doesn't take much.  A heavier strong and aggressive racer on the other hand can handle much stiffer.  If you're a decent skier, then you can probably tell if a ski is too stiff or soft for you when you try it.

 

 

Quote:
Actually, not ALL movements ARE downhill. Do you have a guess as to what I am referring to? 

I knew my statement would be misinterpreted.  ;-)  I meant to say that from a 3rd party perspective, all parts of a skier/ski will be closer to the bottom of the hill after some time x.  There is no time where part of you or the ski goes uphill (assuming normal skiing and not turning until you go up the hill).  I think you're talking about a movement that is "up" relative to the COM of the skier.  In which case the entire transition phase, the COM is being brought from above the skis to below the skis and therefore could be thought of as an "uphill" movement of the skis.

post #220 of 235
Quote:
Originally Posted by majortato View Post

 

Each person is different.  For a beginner/intermediate or a lightweight, it doesn't take much.  A heavier strong and aggressive racer on the other hand can handle much stiffer.  If you're a decent skier, then you can probably tell if a ski is too stiff or soft for you when you try it.

 

 

I knew my statement would be misinterpreted.  ;-)  I meant to say that from a 3rd party perspective, all parts of a skier/ski will be closer to the bottom of the hill after some time x.  There is no time where part of you or the ski goes uphill (assuming normal skiing and not turning until you go up the hill).  I think you're talking about a movement that is "up" relative to the COM of the skier.  In which case the entire transition phase, the COM is being brought from above the skis to below the skis and therefore could be thought of as an "uphill" movement of the skis.

    Now that's a "move" in the right direction (so to speak roflmao.gifYou're starting to get it! Have you ever delved into the realm of foot steering? I'd elaborate, but my wife's givin' me the "stink eye" so I gotta go Rules.gif.  I'll just say that "to tip left, turn right". I know this is somewhat cryptic, but it deals with what our feet do naturally (inside our boots) as a consequence (biomechanically) of rotating our femurs in their sockets and tipping our skis on edge...and what we must do, as good skiers, to counter-act this...

   

 

   Keep in mind, there is a lot to this whole skiing thing smile.gif  (as I'm sure you probably know...)

 

 

   zenny

 

    

post #221 of 235
Quote:
Originally Posted by majortato View Post

 

To an extent.  Too strong of a "spring" and it becomes harder to bend the ski delaying the turn initiation.  Just like everything else in life, always in moderation.

That means in practice that a spring that is just pressed to the bottom in the apex would be ideal, and IMO that is far from the case.

 

what part "pulls" the skis uphill?  Leg movements?  Because I think the legs are trying to be passive at this point (or rather trying to relieve the pressure on the skis).  Also I think all movements are downhill...just a question of more or less.  But for a moment suppose it's a pull....then I say "why not both?"  

A retraction is a very active move in high end skiing, just enough so that you don't lift the skis

 

 

 

post #222 of 235
Quote:
Originally Posted by zentune View Post

      I'll just say that "to tip left, turn right". 

 

    

Very good Zenny, this shows that you have a very good understanding of what actually happens in good skiing.

It doesn't always rhyme well in the steering community though.

post #223 of 235
Quote:
Originally Posted by Jamt View Post

Very good Zenny, this shows that you have a very good understanding of what actually happens in good skiing.

It doesn't always rhyme well in the steering community though.

Its astonishing to me how much we have obscured the simplicity of skiing ie "tip the skis to the left, tip the skis to the right:.  Nonetheless I think the extent to which those movements which produce active steering at slow speeds are present at higher speeds in higher end skiing is greatly misunderstood.  The active leg rotation forces that actually turn the skis in a wedge are the forces that are used to produce counter and hence enable angulation and balancing with inclination in more aggressive skiing. The surest way to see the degree to which this is misunderstood and neglected is to witness the degree to which it is commonly lacking in the skiing of so many. PSIA-E's "Standards" DVD, which I don't much care for otherwise, has a great illustration of this. They show a number of exam candidates at the 3 levels of certification and critique them. In general the critiques are pretty lame IMO but there is a great clip of Herman Maier skiing what is perhaps the best demo of a parallel turn I have ever seen. The contrast between his skiing and that of the candidates is very instructive. If you think about active  ski guidance in a wedge turn and the albeit very slight upper and lower body separation this enables, this is exactly the muscular activity you see being used in his low speed carved parallel turns. I recommend the video which I might otherwise toss in the circular file to anyone for this illustration of great skiing.

 

I don't know what this has to do with "acceleration out of the turn" and I apologize for the tangent but it seemed an opportune moment to bring up something suggested in your post.

post #224 of 235
Quote:

To an extent.  Too strong of a "spring" and it becomes harder to bend the ski delaying the turn initiation.  Just like everything else in life, always in moderation.

That means in practice that a spring that is just pressed to the bottom in the apex would be ideal, and IMO that is far from the case.

 

Not at all.  We want the ski to be bent early in the turn so that it's easier to turn.  Waiting until apex for the ski to be fully compressed would be slow.  And this is far from the case...I think we both agree the ski is fully compressed early in the turn...not at the apex.

 

Ideally, you have a ski that is easy to bend at first, but stiffens up as you pressure it more.  I think a lot of ski manufacturers have tried to do this to their skis.  Atomic Double Decks come to mind, but I know others have marketed similar things.  The extent to which these technologies work is debatable, but the idea behind it is the same.

 

 

 

Quote:

what part "pulls" the skis uphill?  Leg movements?  Because I think the legs are trying to be passive at this point (or rather trying to relieve the pressure on the skis).  Also I think all movements are downhill...just a question of more or less.  But for a moment suppose it's a pull....then I say "why not both?"  

A retraction is a very active move in high end skiing, just enough so that you don't lift the skis

Terminology here is key.  I agree that it's very active in the sense that we have to really try to do it right.  It's not just something that happens automatically.  There are muscle movements that need to happen for it to work.  I'm not comfortable with the word "pull" to describe what's going on here.  I think of the transition as the old outside leg releases pressure on the ski while the old inside leg starts to build pressure on the ski.  This allows the COM to pass over the skis.  The skis move "uphill" relative to the COM and the COM moves "downhill" relative to the ski.  From a 3rd party perspective though, everything is moving downhill at all times.  

post #225 of 235
majortato...you're arguing technique with RACE COACH.

zenny
post #226 of 235
apologies Majortato, if i came across too harshly smile.gif i suppose epic is full of passionate debates!

respectfully,

zenny
post #227 of 235

I don't think I'm arguing technique...just clarifying my thoughts and making sure we're talking about the same thing.  

post #228 of 235
Quote:
Originally Posted by majortato View Post

Not at all.  We want the ski to be bent early in the turn so that it's easier to turn.  Waiting until apex for the ski to be fully compressed would be slow.  And this is far from the case...I think we both agree the ski is fully compressed early in the turn...not at the apex.

Good, then we agree on that. It just that I view it sligthly different, on a hard surface the bending is directly proportional to the tipping. If you manually press the ski more it just means you are pressing in harder against the snow, with limited additional bend.

 

Ideally, you have a ski that is easy to bend at first, but stiffens up as you pressure it more.  I think a lot of ski manufacturers have tried to do this to their skis.  Atomic Double Decks come to mind, but I know others have marketed similar things.  The extent to which these technologies work is debatable, but the idea behind it is the same.

The Double decks are about the classic tradeoff between torsional and bend stiffness. You want a longitudinally soft (relatively) ski, but torsionally stiff. Since the two layers in the double deck can glide longitudinally but not transversally they add torsional stiffnex, but not so much longitudinal.

 

 

 

Terminology here is key.  I agree that it's very active in the sense that we have to really try to do it right.  It's not just something that happens automatically.  There are muscle movements that need to happen for it to work.  I'm not comfortable with the word "pull" to describe what's going on here.  I think of the transition as the old outside leg releases pressure on the ski while the old inside leg starts to build pressure on the ski.  This allows the COM to pass over the skis.  The skis move "uphill" relative to the COM and the COM moves "downhill" relative to the ski.  From a 3rd party perspective though, everything is moving downhill at all times.  

With pull I meant that you are actively retracting the legs, not just relaxing. You want to minimize pressure in this phase in turns where you need a lot of "turn". Off course this is just one example of a turn but it was the kind we were discussing I believe. In general what you are really doing is disturbing the balance in some way so that you float, fly or cross into the next turn. This can be done in many ways and the choice depends on the steepness, offset and length, and it is key to your finish time. 

post #229 of 235
majortato, you should consider Jamts point regarding this being one example of a turn. there are MANY different ways one can apply pressure to the ski at initiation. for instance, some movements are made when entering the top of the turn in order to facilitate an adjustment in regards to line...do you know what i am referring to wink.gif ? if you do, then how much pressure on the skis (and where on the skis?) do you feel would be appropriate? how much would the ski be bending?

zenny
post #230 of 235
majortato, you should consider Jamts point regarding this being one example of a turn. there are MANY different ways one can apply pressure to the ski at initiation. for instance, some movements are made when entering the top of the turn in order to facilitate an adjustment in regards to line...do you know what i am referring to wink.gif ? if you do, then how much pressure on the skis (and where on the skis?) do you feel would be appropriate? how much would the ski be bending?

zenny
post #231 of 235
Quote:
Originally Posted by Jamt View Post

The Double decks are about the classic tradeoff between torsional and bend stiffness. You want a longitudinally soft (relatively) ski, but torsionally stiff. Since the two layers in the double deck can glide longitudinally but not transversally they add torsional stiffnex, but not so much longitudinal.

 

I think you got the D2s wrong - the second deck is long and narrow, except under the plate where it has to be wider - so it's about longitudinal not torsional rigidity. I have a few, in both SL and GS and this is their thing: soft and easy to initiate the turn and they get stiff fast after that. Also, they have a lot less camber than all the other skis I have.

 

Interesting Quote on the D2 technology:

 

This ski is extremely precise. You will initiate the turns with it very easily, and due to D2 technology, the coming out of the turn is extremely fast; the accumulated energy simply explodes, turning this seemingly calm ski into a wild beast that prepares for the next turn with the speed of cheetah. This extremely important feature in ski racing, however, asks for a bit of accommodation.

 

cheers,

Razie

 

P.S. I find it interesting that in WC, nobody uses D2 for SL but for GS and faster events.

post #232 of 235
Quote:
majortato, you should consider Jamts point regarding this being one example of a turn. there are MANY different ways one can apply pressure to the ski at initiation. for instance, some movements are made when entering the top of the turn in order to facilitate an adjustment in regards to line...do you know what i am referring to wink.gif ? if you do, then how much pressure on the skis (and where on the skis?) do you feel would be appropriate? how much would the ski be bending?

 

Lots of possible answers here I think..but I'm gonna guess you're talking about the stivot?  

 

Regarding the D2's, I remember reading something about it that markets it to increase longitudal stiffness as the ski is bent.  The bottom deck bends fairly easily until a certain point when the top deck engages and adds to the stiffness.  A lot of people rave about them...my buddy got a pair but he wasn't as impressed.  He does like to rush his turn initiations though, so I think the advantage is lost on him.

post #233 of 235
thats right, majortato! but it was a two part question. think about it...


zenny
post #234 of 235
Quote:
Originally Posted by majortato View Post

 

 

 

 

Terminology here is key.  I agree that it's very active in the sense that we have to really try to do it right.  It's not just something that happens automatically.  There are muscle movements that need to happen for it to work.  I'm not comfortable with the word "pull" to describe what's going on here.  I think of the transition as the old outside leg releases pressure on the ski while the old inside leg starts to build pressure on the ski.  This allows the COM to pass over the skis. Also, majortato, when referring to the type of retraction turns that we have been up until recently, we usually refer to the BoS as "crossing under" the CoM. CoM "crossing over" is a different transition. "Terminology here is key."  The skis move "uphill" relative to the COM and the COM moves "downhill" relative to the ski.  From a 3rd party perspective though, everything is moving downhill at all times.  

   zenny

post #235 of 235
Quote:
then how much pressure on the skis (and where on the skis?) do you feel would be appropriate? how much would the ski be bending?

center of the skis..should be a balanced position.  I don't think there is a "proper" amount of pressure...it's however much that is necessary to achieve what is desired.  More importantly is the edge control and the direction the skis are pointed.  The ski would be bending pretty much fully.

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