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# Down-unweighted turns: good or bad in general skiing? - Page 4

Sorry CT the physics is not up for debate, the contact forces and friction cause edge grip to occur. Not a the lack of friction. Go back to junior high school but try staying awake in science class this time around.

Quote:
Originally Posted by justanotherskipro

Sorry CT the physics is not up for debate, the contact forces and friction cause edge grip to occur. Not a the lack of friction. Go back to junior high school but try staying awake in science class this time around.

Strangely, I never have said anything in this thread about either friction per se or the lack of friction.  In the real world, with real physics, not "MA bro" physics, you can in fact get the same turn from a ski with a pretty darn smooth edge, and a ski with a serrated or even wavy edge.  Keep the "physics" keepin' on, though, it's good humor.
What we have he ah, is a failure to communicate.

JASP is using the term steering to imply forcing the edge of his ski into the snow, using some of the very same muscles and applying the some of same in-the-plane-of-the ski (perpendicular to the perpendicular vector coming out of the plane of the ski) forces that ye would use to twist the tips to the right or left in order to get the tips to dig in with the ski being tipped.

CTCooK, quite understandably, considers "steering" forces to be in a direction in the plane parallel to the surface of the snow.
Quote:
Originally Posted by Ghost

What we have he ah, is a failure to communicate.

JASP is using the term steering to imply forcing the edge of his ski into the snow, using some of the very same muscles and applying the some of same in-the-plane-of-the ski (perpendicular to the perpendicular vector coming out of the plane of the ski) forces that ye would use to twist the tips to the right or left in order to get the tips to dig in with the ski being tipped.

CTCooK, quite understandably, considers "steering" forces to be in a direction in the plane parallel to the surface of the snow.

No, that's not it. I understand that steering is being used to refer to trying to get the shovel to bite more once the ski has already been tipped, and if you reread my posts up above including the one where I first refer to sidewall pressure theory you'll see that understanding.  The problem is that this type of "steering" doesn't work, ignores what is actually happening with an engaged ski, and is imo dangerous particularly at the high edge angles where "theorists" argue that this type of steering is most needed.

It's a fun word-game if you're primarily hitting moderate angles and washing out most of your carves anyway.  Instructors may though want to consider why, anecdotally, a lot of them are tib-fibbing on modern skis when for basically everyone else the tib-fib is staying pretty uncommon these days.
At the start of the turn, I have more weight on the tips.   At the end of the turn I have more weight on the tails.

I don't consider it steering, but in order to put more weight on the tip I need to have some vertical torque applied about an axis that is horizontal and perpendicular to my direction of motion.  If my skis are not flat to the snow, but tipped to an angle, this torque, or if you prefer the into-the-snow force at the tips for example, will have a component that is in the plane of the ski and a component that is perpendicular to the plane of the ski.

Your weight must be supported in the vertical direction, this direction is not always straight through the base. Unless you always have equal force x distance behind and in front of the foot with no changes in fore-aft weight distribution, you must have some torque.  Conisder the limit of 90 degrees.  To support your weight and move more weight to the front of the ski, you must have a torque driving the tips into the hill such that a force directed purely to the edge does the driving.  Consider the other limit of no tipping, torque is such that a force is through the base of the ski.   Anywhere in between the proportion of towards the edge torque varies from 0 to 10 percent.

You may not know your doing it, but those forces and torques are present.

I will agree with you in so far as thinking about them as steering probably does little good.  It is far better to just think about moving some weight forward at turn initiation or rearward at turn exit and letting balance take care of things..

Torque is weight times distance.  More weight at the tip means more torque in the vertical direction at the tip.  If the ski is tipped to an angle, some of this extra weight will result in torque with a component about an axis perpendicular to the plane of the ski.

You can ski with centered weight distribution.  It isn't necessary to shift weight to the tips to bend the ski before tipping into a turn.  It is however advantageous to shift weight forward to enhance grip of the tips as turns are started or tightened aggressively.
Quote:
Originally Posted by Ghost

At the start of the turn, I have more weight on the tips.   At the end of the turn I have more weight on the tails.

I don't consider it steering,...[big snip]
You can ski with centered weight distribution.  It isn't necessary to shift weight to the tips to bend the ski before tipping into a turn.  It is however advantageous to shift weight forward to enhance grip of the tips as turns are started or tightened aggressively.

That's good skiing, not steering.

You're also correct that simply through the mechanics of skiing, you will in a variety of ways place some torque/rotary forces/whatever on a ski.  No one from any "theory camp" denies this, it is simple fact.  It's also one reason why torsionally softer skis and snowboards are more forgiving (mellower transition zone, different tunes, etc. are also important parts of this).  One of the strange ironies of the whole "sidewall pressure" thing is people aren't addressing this fact when they get caught up in the "twist ze knee" thing, anyway.
Nice post Ghost.  I can now see where the direction to steer the skis into the snow might have come from.  Well done.

It is also a clear effort to make this "sidewall pressure control" a rotary skill -- and we all know how much Epic loves it's rotary skills.

Getting forward and tipping the skis to drive the sidewall of the shovel into the snow is not a rotary skill. It's a fore/aft balance and tipping skill.  The rotation of the femurs in the hip sockets is an artifact of the tipping effort, known elsewhere as counterbalancing.   It is not the primary tipping mechanism.
Nicely worded Ghost. You and E have the idea. It's an option that doesn't require the levered forward stance. Not that it replaces levering, it's just another way to add pressure to the tip. I want to add a comment here about the suggestion that the knee twists as a consequence of this type of movement. That is very similar to the misunderstanding of knee angulation that suggests the knee actually bends sideways. It's really nothing more than a function of active femoral rotation relative to the acetabulum.
E, the active turning of the femurs in the hip socket is classified as a rotary skill here, even though it's intended outcome isn't to pivot the skis. The graphic I posted a while back with the overlapping circles was developed to reflect exactly this type of interconnected relationship between the skills classifications and the possible outcomes they can produce. I'm not sure how that fits into your system since it can affect edge angle and presure distribution along an engaged edge.
Ski well my friends,
JASP
Quote:
Originally Posted by justanotherskipro

Nicely worded Ghost. You and E have the idea. It's an option that doesn't require the levered forward stance. Not that it replaces levering, it's just another way to add pressure to the tip. I want to add a comment here about the suggestion that the knee twists as a consequence of this type of movement. That is very similar to the misunderstanding of knee angulation that suggests the knee actually bends sideways. It's really nothing more than a function of active femoral rotation relative to the acetabulum.

All the acetabulum in the world can't change that.
Edited by CTKook - 1/6/10 at 11:01am

CTKook said :  a lot of them are tib-fibbing on modern skis when for basically everyone else the tib-fib is staying pretty uncommon these days.

this is not the place to expand on this thought, but if you would start a fresh thread on this I'd like to hear what you mean and what evidence you can supply to back up this assertion.

I am very interested ....  my wife did this a few years ago --  there was a discussion a few years ago when Epic seemd plagueed with 3 or 4 cases.

In the real world you keep mentioning you have no credibility since you don't care to share what you do and your level of expertise in the world of ski / snowboard teaching, or race coaching, or any other subject for that matter. What's up with that? Why not come out of the closet and stop hiding behind your keyboard. Until then all anyone can assume is you have no credentials.

Quote:
Originally Posted by justanotherskipro

It's an option that doesn't require the levered forward stance. Not that it replaces levering, it's just another way to add pressure to the tip.
I am trying to get the shovel to bite more and can see very clearly, in theory, that the rotation of the leg with the ski tipped will result in some additional force pressing into the snow at the shovel. But that additional force requires a much stronger rotational force (or twisting motion) at the leg. Mechanically, the leg is the bolt and the ski is the wrench. Wouldn't it be far more effective, and probably much safer, to shift weight forward and tip the ski - the "levered forward stance"?

Is this a real option in reality? When do you use it?
Quote:
Originally Posted by justanotherskipro

In the real world you keep mentioning you have no credibility since you don't care to share what you do and your level of expertise in the world of ski / snowboard teaching, or race coaching, or any other subject for that matter. What's up with that? Why not come out of the closet and stop hiding behind your keyboard. Until then all anyone can assume is you have no credentials.

justanotherskipro,

May I jump in here? Like you, I dont know anything about CTKook's qualification and expertise, but I dont think that's really relevant to have an intellectually rigorous discussion. He doesn't ask us to "trust me, I know, I am the expert". He presented his reasons (with some "personality" as we all do). If his reasoning is faulty, please point it out.

Ski well, be safe, and keep the discussion active.
CT
Quote:
Originally Posted by justanotherskipro

In the real world you keep mentioning you have no credibility since you don't care to share what you do and your level of expertise in the world of ski / snowboard teaching, or race coaching, or any other subject for that matter. What's up with that? Why not come out of the closet and stop hiding behind your keyboard. Until then all anyone can assume is you have no credentials.

One of your MA bros tried to pull the same "what are your credentials" stuff after arguing for some time that it was impossible as a matter of physics to suck up speed in the bumps through absorption.  Of course, it is in fact possible to do this, and the physics are pretty simple.  The parallels are eery.

In this case, there are some very simple, testable assertions.  You think torque can jump past your knee, going from your "active femoral rotation relative to the acetabulum" to your skis without twisting your lower body at all.  You have credentials out the yazoo, but unless you have some magical torque-shifter patented, you still can't change the way the human body is assembled.  Don't actually do this, but consider using a leg press machine with your body turned sideways; also wear ski boot and skis, and place some benches under tip and tail of your skis to mimic some of the loads of skiing reasonably closely.  Then with a heavy load -- because we're talking a high edge angle turn, and at high edge angle you will have some decent forces to deal with -- try some active femoral rotation relative to the acetabulum.

Again: don't do this.  Your gym wouldnt let you do it, because of the high injury risk, anyway.  And I don't want you to get hurt.  I have had knee injuries, and they suck.

Credential that.
Chuck, I don't think everyone needs to be a certified ski pro to participate in discussions here. Although in CT's case I think it's fair to ask him his qualifications since he seems to have represented himself as some sort of expert in the sport. His unwillingness to produce any qualifications say a lot in my book. So does his colorful and negative attitude towards people who disagree with him. I've worked for and with some of the top pros in my country and not one of them exhibit his need to denegrate others, like that somehow makes his opinions more valid. If anything their attitude is to be very open and respectful of others because their ego isn't challenged by a conflicting opinion.
As far as his contention that the torque I was talking about exceeds the knee joint's capacity to handle this load I would say that's pure nonsense based on either a misunderstanding of the idea, or lack of experience on his part. I've turned a ski this way for over thirty years and my knees are fine. I've also turned my skis this way in a tuck and at downhill race speeds without the catastrophic results he insists must happen. BTW, A former US downhiller was one of my bear's speed coaches and we helped her learn how to use this move very effectively and guess what her knees survived just fine on her way to winning a lot of ski races.
So to suggest the idea is exclusive to my "MAbros" is laughable. Then again that coach had credentials and was the head coach of one of the most respected race academies in our state. Something CT seems to view as a sign he wouldn't know his stuff either.
Edited by justanotherskipro - 1/6/10 at 7:55pm
Quote:
Originally Posted by justanotherskipro

...
As far as his contention that the torque I was talking about exceeds the knee joint's capacity to handle this load ...

So, basically, contrary to your earlier assertion that what you're advocating won't twist your knee, you're now saying your knee will be subject to torque but the knee should be just fine?  Torque that magically bypasses the knee, or torque but only a precisely engineered amount of torque that you're confident the knee can withstand?

All the other stuff is chest-thumping about your perceived social "rank" in the sport.  I actually have had my kids coached by a pretty good group of folks, for instance.  But can actually explain on a substantive level why, if you try to pressure the shovel of an engaged, high edge angle ski with active rotary forces, your knee and lower leg will of necessity also experience those forces.  Anyone doubting that those forces are potentially harmful I'd encourage to actually try the tin can thing:  drink a Coke (Pepsi if you absolutely must, for science), stand on the empty soda can (I weigh 195 right now and if I'm careful it'll still support my weight) and then tap the side with your finger.

You'd said earlier that you wouldn't twist the knee doing this, now you seem possibly to say that your knee may experience torque but we should trust you that our knees will be fine.
Quote:
Originally Posted by justanotherskipro

E, the active turning of the femurs in the hip socket is classified as a rotary skill here, even though it's intended outcome isn't to pivot the skis. The graphic I posted a while back with the overlapping circles was developed to reflect exactly this type of interconnected relationship between the skills classifications and the possible outcomes they can produce. I'm not sure how that fits into your system since it can affect edge angle and presure distribution along an engaged edge.
Ski well my friends,
JASP

For those that remember the graphic, it was 3 overlapping circles, one representing rotary, another edging and the third pressure control.  The notion is to indicate that there are some movements that require skills in all areas.

It is not intended to indicate that all movements require skills in all areas.  One could argue that flexing/extending on a tipped ski shows edge control as well, since the ski is tipped while your doing it.  NO. Those are independent actions.

It is the same for tipping and what appears to be the *active* rotation of the femurs.  Try this:

stand straight up and tip your feet.  Not much tipping right? Now flex.  What happens is that the knees move to the side by rotating the femurs in the hip socket.  As you extend, the rotation goes away.

Now you may say that is proof that you are using skills in all three areas at once, just by tipping.  That is not the case.  What you've seen is the kinetic chain in action -- a biomechanical reality.  It is not proof of "skills", it's just how we are wired.

To an outside observer, the appearance will be of active rotation.  That is how we get into this mess.  Perception is not reality.  I'll bet that every time someone sees a skier tipping their skis and sees the rotation of the femurs, they shout "look rotary skill"!  The above example shows that is very far from the truth.

Having said all that, the diagram is correct, an active rotary  movement can influence pressure control.  But ask yourself:  Just because you can, does that mean you should?

A forward movement of the body will produce FAR more useful force on the shovels of the skis than attempting to add that force by rotation.  At best, it is a subtle change, especially while travelling at speed.
Quote:
Originally Posted by BigE

...Having said all that, the diagram is correct, an active rotary  movement can influence pressure control.  But ask yourself:  Just because you can, does that mean you should?

A forward movement of the body will produce FAR more useful force on the shovels of the skis than attempting to add that force by rotation.  At best, it is a subtle change, especially while travelling at speed.

Re: the ability to influence pressure control:  absolutely true.  But, as a rotational force, it will only be either the shovel or, possibly, the tails (depending on the rotary input) that are pressured and, given the very large inputs that will be needed to influence the shovel from the weak end of the lever, once the input is given it's hard to take back.  Leaving the health of your lower body to one side, if you are mid-carve levering onto your shovels in a way that leaves you generally "hanging out on your shovels" frequently may not be what you want for finishing the turn in a good way.  A benign result would simply be losing the tails of your ski from the turn.

And thank you for a very substantive post Big E.
E,
Actually the graph is suggesting all three skils are present to some degree in all turns. At least in our system. I fully understand your system doesn't recognize that but that point needs to be made clear. You opinion is based on a slightly different set of assumptions like abduction / adduction being strictly a tipping skill, where we see it as containing elements from all three skill pools.  Like you pointed out flexing a leg allows the knee to abduct while the foot remains relatively in place. The outcome being the sole of the foot tipping along the long axis of the foot. Both systems recognize this outcome. We break this down a little further because it takes flex in the hip, knee, ankle,and the femurs rotating in the hip socket to produce that movement. Which interpretation is correct? Both are within the context of their system and neither are outside of their systems.
BTW, The steering movement isn't really as strong as you guys are suggesting. Niether is the levering move you suggest is a better option. If it was the tips would grip and the tails would whip around and pass the tips. By remembering that we're talking about balancing and turning movements at speed, the whole assumption of huge movements should be eliminated from the discussion. We're talking about changing the pressure distribution and allowing the skis to turn, not forcing them to pivot around the tips.
As far as perceptions, hip angulation and counter require the very same leg steering we've been discussing. At speed we try to minimize counter but do we totally eliminate it? Hardly.
Ski well my friends,
JASP
JASP,

Cut it out, hip angulation does not require steering of any sort.

Actually the pelvis facing one way and the knees another does E. Unless of course you keep the pelvis square to the skis so the knees and the pelvis face the same direction. The limited RoM of this pure lateral form of hip angulation isn't what I'm talking about. Here's a Lemaster montage that shows what I've been talking about. Notice the internally rotated outside legs and the externally rotated inside legs? Frames four, five, and six especially. You can call it whatever you want but the femurs are definitely turning under a relatively stable pelvis and body.

BTW, CT Notice the flexed stance through the transition, down unweighted? Sort of, Flex to finish? Absolutely. So much for the BS about no steering being possible in a croutched stance.

Edited by justanotherskipro - 1/7/10 at 8:13pm
Quote:
Originally Posted by justanotherskipro

....

BTW, CT Notice the flexed stance through the transition, down unweighted? Sort of, Flex to finish? Absolutely. So much for the BS about no steering being possible in a croutched stance.

So you're trying to claim a flexed, compact transtition represents steering these days?  LMFAO, again.

In the real world, a, say, race coach looking at that is not going to see a steered turn.  While with a montage it's hard to tell, I do infer a skid before the skis fully engage, let's say in real time between images "4.5" and actual image 6.  That's way different than steering, particularly on that snow.  Inside hand and shoulder forward, hips countered, even by image 5.

It's hard to keep up wtih "MA theorist word games."  If the current word-game is to look at that skiing and say, "Classic rotary, this is what pivot slips can take you to," then groovy.  It's a steered turn in YOUR MA-thought-world.  Steer on.

Oh, wait, I take it all back.  Between images 4 and 5 I see a hint of a classic Tai Chi stance, and there's definitely some femur mojo pumpin' by the acetabulum.  So, the actual real-world mechanics of what's happening to one side, clearly there's not just steering, but very intellectually fashionable steering.
Quote:
Originally Posted by CTKook

So, the actual real-world mechanics of what's happening to one side, clearly there's not just steering,

Real world mechanics aside? Doesn't that say your opinion isn't based in real world mechanics?

Discount whatever system you want, it really doesn't matter. At least in the real world.
In the real world are you a race coach? Or are you just suggesting you can speak for all race coaches?

Looks to me like she was low on her line on the red gate and had to switch quickly, so she flexed to release the right footed turn and immediately pushed her skis to her left and lined them up for the next turn. She is back on the line for the blue.

What can't be seen in this single montage is whether her line at the red gate was the desired line or not or if there is a roll between the red and blue (very flat light). She might have been low and made a move to get back, she may have had to deal terrain or both.

I don't know how 'steering' has been defined for the purpose of this thread, so I won't say she steered or not. Her skis moved through about 45 degrees clockwise from release to engagement. Somewhere between the last frame and the previous one, her skis engaged so we can't say exactly how many degrees they turned before being pressured. Whatever you call it, athleticism perhaps, it was done while the skis were light. It was pretty effective. The movement included extension of the legs as well as femur rotation. The rotation was used to insure that neither the tip nor tail was engaged until the skis were pointing in the right direction. If her femurs hadn't rotated, but she had extended her legs, her tails would have hooked up. Not a desireable result.
Quote:
Originally Posted by MastersRacer

... The movement included extension of the legs as well as femur rotation. ...

Was rotational input added by pelvis, waist, or upper body, or taken away?  Did the hips counter rotational input or add to it?

The fact that there's  a ball and socket joint doesn't address whether you're using rotary forces to steer a turn.

Let's say hips had stayed square or even "waist-steered," inside arm and hand had been back -- how do you think that would've ended up?

Also, re: your inferred skivot/stivot vs my infered skid, you need to stretch the visual plane back out from the montage (the montage shortens the amount of ground actually covered) so as a technical point I don't think the change in direction of skis was as abrupt as you may.  Taking your view though, active rotary would've blown the turn and possibly led to a high-side.
Edited by CTKook - 1/8/10 at 8:21am
Or, how bout using a little torque to try to add pressure along the sidewall to those shovels for that turn?  Just a little twist of the hips into the turn, utilizing the "torque shifter" so your lower body doesn't experience the torque, so that the boots pivot the front of the sidewall into the snow?
Nice post MR.
CT you still havn't answered my question. Why the evasiveness? What are you hiding? Why are you hiding it?
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