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# Relatively new to shaped skis - do I pick - Harb (PMTS) - Clendenin Ski Method - Klaus Mair (Sofa Ski School) - Page 3

I think most have been said in this thread now, I'll just add some basic physics.

Releasing forces does not eject or project you in any way. When you release the forces you just keep going in whatever direction you were going. That is why you need to have started the CoM upwards movement before you retract. Eventually gravity will take over and get you down again.

There is very little energy stored in a bent ski. I can bend a ski the same amount with one hand, it is not enough to cause float or rebound.

The following may not be basic but it is important to understand if you want to understand how skiing works:

The forces on the skis have a component perpendicular to the surface and a component tangent to the surface. The tangent component is always there if you are turning and it is what makes the turn. The perpendicular component affects the relative height of the CoM and it is also necessary to get grip. The perpendicular component is on average proportional to your weight. The only thing you can do is distribute the force differently in the turn. If this component is high when the skis are not on high edge you are wasting it. If it is high in the apex you get good grip. If your CoM is on a constant distance to the surface the perpendicular force is constant. This does not work outside of good conditions/easy terrain and it will never allow you to reach high angles. This type of skiing is also done be flexing in transition, but it should not be confused with the reasons that racers flex.

In summary CoM up and down is good, but not if you create it artificially.

Edit: One example when this is applicable is ice. Many skiers tense up and have more pressure in transition when they ski ice, but what you really need is agressive retraction that minimizes the pressure in transition. That will give you ice grip.

Edited by Jamt - 1/30/13 at 12:42am

what ever happened to good skiing is good skiing and this is how you go about it LOL

Edited by ozskiguy - 1/30/13 at 3:03am
Quote:
Originally Posted by Jamt

There is very little energy stored in a bent ski. I can bend a ski the same amount with one hand, it is not enough to cause float
I certainly don't know your skis, but when i bend mine into a reverse camber, there is a lot of energy there and when i let go, the sucker will float a few feet to the other side of the room... Yes, there is more in my race skis than my regular softer skis, but quite enough to get the ski and boot to float, i assure you. Not floating the entire body, since you're not pushing but flexing, but just the skis, helping me use less energy in retraction - but repeating myself now
Quote:
Originally Posted by razie

I certainly don't know your skis, but when i bend mine into a reverse camber, there is a lot of energy there and when i let go, the sucker will float a few feet to the other side of the room... Yes, there is more in my race skis than my regular softer skis, but quite enough to get the ski and boot to float, i assure you. Not floating the entire body, since you're not pushing but flexing, but just the skis, helping me use less energy in retraction - but repeating myself now

Do the following experiment razie. I'm assuming that you edge the skis about 45 degrees. Put the ski at 45 degree angle towards a flat carpet and press down with your hand. Release and see how far it flies. repeat with 10 kg boot+leg.

Quote:
Originally Posted by ozskiguy

what ever happened to good skiing is good skiing and this is how you go about it LOL
Yeah - we got you to blame

I think the method choice was settled long ago and good skiing is in the eye of the beholder. Skiing tall can be good skiing if you are balanced, stable and in control. I can ride my motorcycle at low and high speeds without "hanging off" through turns and is good riding. It's not "performance riding" but good, stable, in control and with a big smile . If i want to push it though and get some adrenaline flowing, I know exactly what to do.

Same with skiing. I assure you the same kind of discussions happen on some motorcycle forums. It is, as everywhere else in life, a matter of choosing your advisers smartly.
Quote:
Originally Posted by Jamt

Do the following experiment razie. I'm assuming that you edge the skis about 45 degrees. Put the ski at 45 degree angle towards a flat carpet and press down with your hand. Release and see how far it flies. repeat with 10 kg boot+leg.
60-70 at least and quite often 180, thats why i wear an orange jacket: easily visible in the trees

(Edit) This is before getting deep angles and it's still over 60 it looks to me - outside ski, right? http://m.youtube.com/watch?v=nG9ldu0Kl14
Quote:
Originally Posted by ozskiguy

Background

Coming over from Oz in Feb. First up I need to become a better skier on shaped skis as I am new to shaped skis - maybe 4 days so far :)

I am advanced intermediate ( but have done many black runs and even a few double black) however I only recently changed to shaped skis and bought new boots.

Many years ago I was lucky enough to stay at a house owned by the guys that ran the Race School at Mt Hutt in New Zealand. They coached some of us and I have to say that is the only instruction I have ever had.

Priority 1 - I need to become a better skier on shaped skis before doing any camps next year and beyond etc.

I have a Tahoe Value Season Pass (Heavenly, Kirwood and Northstar).

Options so far

I have Harold Harb's Essentials of Skiing book (which I have read in some detail) and a number of his video clips but not

I have Klaus Mair's Sofa Ski school DVD which I have not really looked at much yet.

I have John Clendenin's book (not read yet) and intend to get his DVD sent to my friend's San Francisco address before I arrive.

Challenge

I don't want to go through too much technical detail or spend many hours (100 plus) researching methods. Been there and done that with golf (1000 plus hours).

I know the Inner Game stuff and stay with one of the original Extraordinary golf coaches in San Fran so I will use that approach to coach myself on the "method" I choose.

I am 54, I love snow skiing and I intend to spend a lot more time on the snow in future years. Fitness and strength are a long way from where they were when I learnt to ski.

I don't want to pick a method that will teach me bad habits as I intend to progress.

I know this is big ask but I would like your feedback on my situation and options.

I think I need to pick one DVD/video series and stick with it until I am more proficient on shaped skis. Then I can build from there next season.

I believe PMTS and Clendenin are compatible with each other (Clendenin is accredited in PMTS).

Klaus Mair - I do not know enough yet to know if his teaching is compatible with Harb/Clendenin. Hopefully it is as he runs a camp in Treble Cone NZ which I could go to later this year.

I know shaped skis are designed to work in a certain way and possibly all approaches should work however that is like saying golf clubs are designed to work in a certain way so just use them as they are designed to work.

Help :)

Chris

Northstar is my home mountain and I'd be happy to give you a few really good recommendations for a ski instructor.  FWIW, the Tahoe region has some really great instructors.

For starters:

Heavenly, Robin Barnes or Heidi Ettinger

Northstar, Marcel Vasquez, Greg Felsch, Eddie Visser, Spencer Abbott, Wade Holiday

I'm sure I'll think of a few more but these are a few off the top of my head.

You can shoot a PM to Spencer Abbott, Wade Holiday or Robin Barnes here on EpicSki.

"The current Canadian 'style' seems to prefer upward release energy over useful release energy"

OK, we can agree to see different things. I'm good with that.

I see the "upward release of energy" as more of cross over then cross under, and a cross over turn, I consider more of an extension as opposed to retraction, not black and white, but I see JF's demo turns from the video I posted as more cross over.

Ozskiguy, sorry for the derailment. the hot words in your question were pmts. things get a little devisive around here w/ that topic. I own and have read all HH"s books and enjoy his teaching ideas. as mentioned, I taught and trained for about 5 years w/ Eric DesLauriers, and he likes to teach many of the same ideas.

maybe we'll meet you in Tahoe.

cheers,

holiday

I was just having a little fun with my last post. I kind of knew of the Harb - PSIA thing from the past but I didn't have any idea of the depth of feeling held by some people. I sure know more now however :)

Thankfully I have been able to interact with a few people who have knowledge of the various approaches mentioned so I hope to benefit from that as I certainly am not qualified to sift thru it all :)

Based on past experience in a number of other areas/fields I have learnt to be wary of the "my way is the best way/ my way or the highway" players. Thats not to say they don't have good stuff but if everything else really was so bad then they wouldn't have time to bash any other players as they would be so busy servicing demand that they would need 48 hrs in a day. Word spreads very fast in the Internet age. Just my 2c worth.

This time next week I will be at Sydney Intl Airport waiting to board our flight to the US. Then up to Reno/Tahoe after a few days with friends in Benicia (San Fran). Can't wait.

Chris

Quote:
Originally Posted by razie

60-70 at least and quite often 180, thats why i wear an orange jacket: easily visible in the trees

(Edit) This is before getting deep angles and it's still over 60 it looks to me - outside ski, right? http://m.youtube.com/watch?v=nG9ldu0Kl14

70 is what WC racers reach, this is not 70.

The only way you can feel any force from the ski is the way the it moves. If the ski still moves on the surface it will not affect the up movement of your feet and it will not cause any float of the ski. The float is caused by CoM trajectory.

Quote:
Originally Posted by Holiday

"The current Canadian 'style' seems to prefer upward release energy over useful release energy"

OK, we can agree to see different things. I'm good with that.

I see the "upward release of energy" as more of cross over then cross under, and a cross over turn, I consider more of an extension as opposed to retraction, not black and white, but I see JF's demo turns from the video I posted as more cross over.

Ozskiguy, sorry for the derailment. the hot words in your question were pmts. things get a little devisive around here w/ that topic. I own and have read all HH"s books and enjoy his teaching ideas. as mentioned, I taught and trained for about 5 years w/ Eric DesLauriers, and he likes to teach many of the same ideas.

maybe we'll meet you in Tahoe.

cheers,

holiday

Quote:
Originally Posted by ozskiguy

I was just having a little fun with my last post. I kind of knew of the Harb - PSIA thing from the past but I didn't have any idea of the depth of feeling held by some people. I sure know more now however :)

Thankfully I have been able to interact with a few people who have knowledge of the various approaches mentioned so I hope to benefit from that as I certainly am not qualified to sift thru it all :)

Based on past experience in a number of other areas/fields I have learnt to be wary of the "my way is the best way/ my way or the highway" players. Thats not to say they don't have good stuff but if everything else really was so bad then they wouldn't have time to bash any other players as they would be so busy servicing demand that they would need 48 hrs in a day. Word spreads very fast in the Internet age. Just my 2c worth.

This time next week I will be at Sydney Intl Airport waiting to board our flight to the US. Then up to Reno/Tahoe after a few days with friends in Benicia (San Fran). Can't wait.

Chris

Wade is at Northstar, and there's a rumor going around that he's a good instructor.

"Wade is at Northstar, and there's a rumor going around that he's a good instructor."

Well, at least he seems to be open minded when it comes to ski technique. That in itself would be enough to sell me on taking a lesson with him.

Quote:
Originally Posted by Jamt

70 is what WC racers reach, this is not 70.

yeeehaaa - i'm just 8 degrees behind the WC, if my son's angle finder was not too cheap, i have defeated the dark Sith lord of "upright"  - kidding, although he put up some fight, eh, but as soon as you figure out what to do with the inside knee, it all... literally "falls" into place :)

Quote:
Originally Posted by Jamt

The only way you can feel any force from the ski is the way the it moves. If the ski still moves on the surface it will not affect the up movement of your feet and it will not cause any float of the ski. The float is caused by CoM trajectory.

slightly different point of view here: the release starts at the fall line or immediately after (depending on speed management issues), when the skis are still very bent and very on angle to the snow, with the topsheets facing essentially the direction of the next turning point - the float refers to how the skis get on the other side, edging will occur while floating. there is no up movement anywhere related to the release / energy thing. I would say that beginners and non-racers (I was both not long ago) will not get sufficient angles and flexion to experience this and might fight an "upward" push from the skis instead of a push across...

let's agree to disagree on this one, then - it's almost ski time  i got my son another pair of skis yesterday, to get my "masters" thing back...

cheers,

Razie

Edited by razie - 1/31/13 at 9:57am

Seems you have not understood what I have been writing. If you did you could actually learn a thing or two. Several of the things you have described are simply impossible from a physics point of view. It does not matter what you feel when you are skiing if you cannot relate it to what is actually happening, but sure, lets agree to disagree.

Razie,

Try JamT's experiment....you might be surprised what you find.

No one is arguing what you feel...what is being argued is what is causing it.

Quote:
Originally Posted by Skidude72

Razie,

Try JamT's experiment....you might be surprised what you find.

No one is arguing what you feel...what is being argued is what is causing it.

I've been thinking of extension and retraction a lot lately as I ski (and after joining Epic)...It seems (feels) to me that in retraction turns, it's the LEGS that extend across to the fall line, and in more extended transition turns, its the CoM that extends to the fall line.  Decambering occurs during transition (x-move) as the skis speed ahead of the body. It coincides/coexists with these movements--AND helps make them possible--but it is the movements of the BoS in relation to the CoM (and vice-versa) that gives us the sensation of "rebound", which is also influenced by speed, turn shape, skis, etc...What do you think, Skidude? Is this what you and Jamt are alluding to?

zenny

Quote:
Originally Posted by razie

. It is, as everywhere else in life, a matter of choosing your advisers smartly.

Good point :)

Quote:
Originally Posted by razie

It is, as everywhere else in life, a matter of choosing your advisers smartly.

...have you chosen wisely?

Quote:
Originally Posted by zentune

I've been thinking of extension and retraction a lot lately as I ski (and after joining Epic)...It seems (feels) to me that in retraction turns, it's the LEGS that extend across to the fall line, and in more extended transition turns, its the CoM that extends to the fall line.  Decambering occurs during transition (x-move) as the skis speed ahead of the body. It coincides/coexists with these movements--AND helps make them possible--but it is the movements of the BoS in relation to the CoM (and vice-versa) that gives us the sensation of "rebound", which is also influenced by speed, turn shape, skis, etc...What do you think, Skidude? Is this what you and Jamt are alluding to?

zenny

My advice is to do the experiment....

Quote:
Originally Posted by Skidude72

My advice is to do the experiment....

So...I spend a lot of ski time on a pair of fis legal volkl racetiger wc 165 sl's, marker 14mm piston plate, salomon x3 lab medium flex boots, blah blah blah. When I perform carved retraction turns, they feel like they literally EXPLODE across the slope. And yet, when I tried Jamt's experiment, they didn't do squat...just sort of laid flat on the carpet and died--like some kind of old farm animal that's tired of living

zenny

I think this thread alludes to the fact that stiffness and flex pattern is the most important consideration in ski design.

Quote:
Originally Posted by zentune

So...I spend a lot of ski time on a pair of fis legal volkl racetiger wc 165 sl's, marker 14mm piston plate, salomon x3 lab medium flex boots, blah blah blah. When I perform carved retraction turns, they feel like they literally EXPLODE across the slope. And yet, when I tried Jamt's experiment, they didn't do squat...just sort of laid flat on the carpet and died--like some kind of old farm animal that's tired of living

zenny

Yup....that is what you should have found.....so what does that tell you about how much energy is stored in a flexed ski?  Its squat.

So what causes that explosion sensation?  Vaulting, combined with VB.

Quote:
Originally Posted by Skidude72

Yup....that is what you should have found.....so what does that tell you about how much energy is stored in a flexed ski?  Its squat.

So what causes that explosion sensation?  Vaulting, combined with VB.

So as a skier moves thru transition/"finishiation", the resulting forces on the skis lessen, they are rolled flat and are thus decambered, simple as that...no spring from the ski whatsoever. I can clearly see this now--in my minds eye!

P.s. I think I understand your point  from that "one thread" more clearly now!

zenny

A bent ski is a simple leaf spring.

When you bend it in a 2g turn you are loading it with 200-300 pounds of force.

This has nothing to do with pushing it with your hand on the floor.

If you let it snap back it will lift you off the ground.

If you have good technique and release that energy to do something useful in the transition you have a great turn.

Take an ole pair of skis and support them by the tips and tails while you bounce on them.

They make a right fine trampoline.

When technique fanatacism ignores physics, something is wrong....................

Ski designers put in damping rubber layers to keep spring back and vibration under control.

Quote:
Originally Posted by dakine

A bent ski is a simple leaf spring. With a pretty weak spring constant

When you bend it in a 2g turn you are loading it with 200-300 pounds of force. That force is mostly supported by the snow, not the bending of the ski. Supporting a ski by its tip and tail then stand on it or push on it with 200 lbs of force to see how much it has to bend to support that load - A lot and may damage the ski.

This has nothing to do with pushing it with your hand on the floor. Why not?

If you let it snap back it will lift you off the ground.

If you have good technique and release that energy to do something useful in the transition you have a great turn. Force is not energy. The energy stored in the ski is proportional to its spring constant and the square of its bending (loosely speaking) which is very little to launch or vault a skier as the Jamt's experiment demonstrates

Take an ole pair of skis and support them by the tips and tails while you bounce on them.

They make a right fine trampoline. Not sure about that. I permanently bent and ruined a ski in moguls that way by mistake. But that was just a recreational ski

When technique fanatacism ignores physics, something is wrong.................... Sure, but the wrong physics is ... wrong

Ski designers put in damping rubber layers to keep spring back and vibration under control.

Thanks Chuck. To elaborate, this is something I cut and pasted from the iconoclastic turn thread:

In a normal turn on hard flat surface the ski the ski bends about 2 cm. Lets assume that the ski is pretty stiff and has no rocker, then it would take perhaps 200N max force to bend the ski.

If we assume that the ski "spring" has not reached its elastic limit the energy stored in the ski will be:

E=0.02 * 200 /2=2 Nm.

Just for fun lets calculate how much 2 Nm can launch a 100 kg person.

mgh=2 => h=2mm

So, in a typical turn the energy stored in the ski can launch a person about 2 mm,  or 0.08 inches if you prefer imperial. Not much of a rebound to collect there.

Lets compare that to the real physics behind rebound, converting Kinetic energy to potential energy.

If you are going e.g. 36 km/h the Kinetic energy is

E=mv^2 / 2=5000 Nm

Repeating the above calculation we get that this energy, if it is completely converted to potential energy, can launch a skier about 5 meters in the air.

It should be clear that this is the major energy that causes rebound, and that it is something that need to be controlled (by flexing to release)

This is similar to the speed and height a pole vaulter can run/increase CoM height . Same basic physics.

Quote:
Originally Posted by zentune

So as a skier moves thru transition/"finishiation", the resulting forces on the skis lessen, they are rolled flat and are thus decambered, simple as that...no spring from the ski whatsoever. I can clearly see this now--in my minds eye!

P.s. I think I understand your point  from that "one thread" more clearly now!

zenny

Bingo!  This rolled flat, is the other kicker, as the "rolling" is relativley slow...so not only is there not alot of energy there, it is released "relativley" slowly as well.

Skiing is only as complicated as we choose to make it.

dakine is getting it - you guys somehow confuse the snow for cement, through which the ski cannot possibly carve a path. Also, jamt's phisics says that banging your head into a non-movable wall, will not hurt, because you cant really feel a force when the wall is not moving in your direction... that's a good experiment to try at home for the physics aficionados

Considering there is considerable weight on the inside ski here, think how much would the outside really bend with all weight on it: http://media.oregonlive.com/olympics_impact/photo/tommy-ford-skijpg-f9ab154856f90335.jpg - if you dont think that really stiff ski will push back at his legs when released, I really want whatever you are smoking.

Edit - Interestingly, helluvaskier reminded my of something i have to partially agree with now: if you haven't really been forward on a stiff ski, you are lacking some comprehension for what that means...
Edited by razie - 2/1/13 at 4:00pm
Quote:

...have you chosen wisely?
I think so, yeah. I got a ton of stuff from the CSCF guys and tons of stuff from certain books on skiing and "worldly wisdom" and such, and some great and some not so great feedback on certain forums, yeah. I use my filter all the time... If you don't doubt it first, you won't really get it, right?

The newer CSCF levels 3-4 know their stuff too... I would like you to see some of them.
Quote:
Originally Posted by razie

dakine is getting it - you guys somehow confuse the snow for cement, through which the ski cannot possibly carve a path. Also, jamt's phisics says that banging his head into a non-movable wall, will not hurt, because you cant really feel a force when the wall is not moving in your direction... that's a good experiment to try at home for the physics aficionados

Considering there is considerable weight on the inside ski here, think how much would the outside really bend with all weight on it: http://media.oregonlive.com/olympics_impact/photo/tommy-ford-skijpg-f9ab154856f90335.jpg

It's all good fun. But although I have never been on WC ice, I heard it is pretty hard and some skiers actually carve on it. What's the key relevant difference between cement and ice here?

I am banging my head, figuratively, trying to figure out what you want to demonstrate with your "experiment". Anyway, pain is not a physics entity or concept.

Biking fast down a steep slope and squeeze the front brake hard. There is no deformation or bending of any thing, but you can experience a launching or vaulting effect. (I don't recommend you do this experiment. But I've got a feeling most people know what I'm talking about here)

I'm going skiing tomorrow, whoohoo, and will do some experiments.

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