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why is banking bad? - Page 2

post #31 of 46
Nothing really to say. Just have some people I want to check this thread out, so I'm Kicking it back to the top of the column!!
post #32 of 46
<BLOCKQUOTE>quote:</font><HR>Originally posted by ryan:
form (ugly) or function (inefficient)? is it putting the CM where it shouldn't be in a turn. i DO see competitive skiers bank, but it's rare. maybe i'm seeing something else? <HR></BLOCKQUOTE>

Ryan: RE: Banking is technically refered to as tipping the upper body,ie-the torso to
the uphill or inside side of the turn.

If we look at the body as two primary axis, one running vertically with a break at the waist, and the other running horizontally ie-our shoulders, then we can visualize what happens when a skier in motion trys to stay in a dynamically balanced stance in a turn,due to changes in the positions of each axis. Remember that the CM is affected significantly due to movements of each axis either to the inside of a turn or to the outside of a turn. For instance, assume you have just completed a medium radius turn and you're now in the transition point and about to initiate the next med turn in the opposite direction.

Visualize the following: I am just finishing a medium turn with my upper body including my head,shoulders,arms and torso,tipped inside.Where is my CM exactly at this point in the finish phase of the turn? Is it inside of my inside skis outside edge or is it somewhere between both my skis inside edges? Think about what I said in reference to my shoulders in particular.If they're tipped inside are they level with the horizon, relatively speaking? Or is the outside shoulder,arm and hand, higher than the inside shoulder, arm, and hand? The answer is that invariably the outside shoulder, arm, and hand are higher than the inside half of the body.

Now to belabor this just a little longer, visualize the reverse with the inside shoulder higher or at least level with the horizon and the inside arm and hand also higher than the outside body parts. Where do you think my CM is now, as I move through the turn?

Looking back at the axis'man we find that the vertical axis for the torso should now be quite vertical,while the horizontal axis of the shoulders will be relatively level to the horizon or slightly tipped out over my outside ski. The lower half of the vertical axis is tipped to the inside or uphill.Where do you think my CM is now? Is it outside of my inside skis' uphill edge or is it somewhere centered between both skis?

Now that we're in an angulated position, our upper body counteracts the forces of gravity which try to cause us to fall, ie ice-etc. when we are moving in a dynamically balanced position across it. If we were BANKED OR TIPPED inside on the same ice gravity would win and we would fall to the inside or uphill side of the turn because our CM is too far inside the turn for us to recover, while if we are in an angulated stance we will probably recover because our CM is already positioned to move toward the new turn.

Finally to sum it all up: Newton said that a body in motion tends to stay in motion unless counteracted by some other intervening force. PS:I'm not a physics major or engineer so this one is on ME!

GOOD LUCK. Thanks for your question.

: : : :
post #33 of 46
Ryan: Banking? I'm going to try to give you a visual presentation with a guy I'm going to call Axis Man. Axis Man is comprised of two axis. One vetical with a break at the waist and the other is horizontal at the shoulders. In addition, think about the CM and how it moves in a turn. Axis man has just finished a medium radius turn and is in the transition phase. If his horizontal axis is tipped far inside the turn ie-leaning uphill, then where do you think his CM is at this point? Imagine his outside hand, arm, and shoulder being higher than his inside hand, arm, and shoulder. In this position he is almost stuck because his CM is over the centerline of his inside ski or possibly outside of his inside skis' outside edge-ie uphill. Stand up and try to see if your CM, when over your inside skis'centerline, is easy or hard to move back in the direction of the new turn? Now reverse Axis man's position to have his inside hand, arm, and shoulder higher than his outside hand, arm, and shoulder. Now where is his CM? Is it well inside the turn uphill or is it somewhere in between his skis positioned to move into the new turn? Now he is in an angulated position and clearly in a dynamically balanced stance, so he's ready to withstand the forces, which pull on him when he skis over surfaces such as ice, etc. Next time you're out try the same exercise. Do a series of turns with your torso including your outside hand, arm, and shoulder higher than your inside hand, arm, and shoulder and see if you're stable or beginning to fall uphill? Or is your CM moving toward the new turn? If it's hard to set up for the new turn then gues where your CM must be? Too for inside I would suspect. Now try it the other way and see if it works easier in an angulated position? I'm betting that it will be easier. Good luck and happy turns. Whtmt
post #34 of 46
Wow! How did I miss this topic.

Spag, thanks for bringing it back to the top.

I second what Robin said. I thought I was reading an article by Dr. Twadorkens, only I can understand PhysicsMan. I was even able to mentally draw the stick figure of the one legged skier and apply all the force vectors. I have studied physics, I work in the civil engineering field (landfills), I get what you are talking about. Most of the time when people try to explain skiing in extremely technical terms I get turned off. They loose me with babble, techno-wannabees mostly. This hits it on the head. Bob B., great follow-up. This thread is a keeper. I have to print this and add it to my folders with “TPS”

Thanks,

Jim O’D
post #35 of 46
Thread Starter 
thanksto "all y'all."

<FONT COLOR="#800080" SIZE="1">[ October 12, 2001 11:52 AM: Message edited 1 time, by ryan ]</font>
post #36 of 46
Phys-man & bob, Count me in on that "grateful" audience.

Last spring at a clinic, our Ski School director (and PSIA examiner) fell into this very discussion when he recieved a dozen or so perplexed faces upon his asking someone to define all three terms.

He was able to easily clear up WHAT each of them looked like using ski poles to show the angles of the upper and lower body in relation to the slope.
However you've helped me to further refine (to myself) why it is that we incline/angulate/bank. Now if I can find a way to translate this to more students I'll be all set.

Thanks guys.
post #37 of 46
Because they always bounce my checks. Bastards.
post #38 of 46
This seems to pertain to my questions about correlations between waterskiing and snowskiing... Obviously waterskiers (on one ski, also known as "slaloming") do what I am assuming is "banking": leaning as far into the next turn as possible to create more angle on the water, and thus generating greater force. However, there are pulled by a boat, not by gravity, so their speed is constant, more or less. Of course they accelerate through the turn depending on the edge angle, but the same is true on snow. In waterskiing, angulation is bad because the hips are thrown out and the body is upright, making for a rough transition into the next turn and a likely fall. However, if the snow skier is not angled, just like the waterskier, is he more stable at a high speed? I guess I should take into accounting that it is not possible for only the legs to move through a turn on water. A quiet upper body is not possible (except when compared to the lower body... there is lateral movement involved, and the position on the water does not change, but the upper body's banking contributes heavily to the force of the turn). So I guess what I'm asking is this: is it possible to combine the two? Can one be banking and angulating at the same time? I have often wondered about powder turns and leaning into the next turn, but I never knew if this was bad for the turn or not. Any info would be appreciated, thanks.
post #39 of 46
Quote:
Originally posted by Maxilovesthepow:
... So I guess what I'm asking is this: is it possible to combine the two? Can one be banking and angulating at the same time? I have often wondered about powder turns and leaning into the next turn, but I never knew if this was bad for the turn or not. ...
Of course, before we can begin to discuss an excellent question like yours, we first have to agree on Formal definitions for banking, angulation, edging & inclination, so your homework assignment for tonight is to skim through the above short, easy-to-read thread, take two aspirins and see me in the morning for the required test.
[img]graemlins/evilgrin.gif[/img]
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Seriously, tho, as you probably have already figured out from my attempt at humor above, the above thread is indeed relevant to your question, but it got waaay too detailed for most readers, and even prompted a bit of derision from the "Shut-up-and-ski" crowd (mostly from other Internet forums), as well as debate between established instructors preferring historic definitions versus a race coach and a techno-weenie who will, of course, remain nameless .

Anyway, the short answer to your question, "Can one be banking and angulating at the same time?" is that it depends on the definition of banking that you prefer to use.

To try to summarize the previous thread (and I'm sure I will be corrected if I don't get it right), the majority of people that participated in the earlier thread define banking as leaning of one's center-of-mass without any of the banana shaped contortions of one's body commonly known as "angulation". Thus, by definition, banking and angulation simply can not occur together. This group calls the combination of a center-of-mass lean and the banana shaped contortion as "inclination".

I (and if I recall correctly, a race coach) find the above classic definitions confusing, and prefer to simply define the angle of bank as the amount by which the CM is leaning over. I then define angulation as the amount of extra edge angle resulting from any ammt of banana shaped bodily contortion, and I then define that one isolated component as the angle of angulation. With the above definitions that I/we prefer, you most certainly can be banked AND angulated simultaneously, and the combination of the banking and angulation puts you in the desired state of "inclination".

At this point, I feel its an uphill battle to try to redefine these historically entrenched terms, so I've pretty much given up, and so will attempt to answer your question without ever using them:

"Yes, you most certainly can combine a non-zero CM lean angle with extra edge angle obtained by contorting your body. In fact, this one of the most desirable and most used approaches in racing and advanced recreational skiing. Among the reasons for this is that it provides stability and balance."

Phew. Hope this helped (and didn't muddy the waters further).

Tom / PM

[ November 17, 2003, 08:32 PM: Message edited by: PhysicsMan ]
post #40 of 46
Quote:
Originally posted by PhysicsMan:


"Yes, you most certainly can combine a non-zero CM lean angle with extra edge angle obtained by contorting your body. In fact, this one of the most desirable and most used approaches in racing and advanced recreational skiing. Among the reasons for this is that it provides stability and balance."

This is a new one on me. It's certainly not among the "most used approaches..." And it's not responsive to the original question, "why is banking bad?"

To answer the question in the simplest possible way, banking is "bad" in most turning situations because it doesn't allow enough edge angle to prevent skidding through the turn. Banking is inclining the entire body without angulating. (Don't start another discussion of definitions- these are the standard definitions used in ski instruction.) Increasing the edge angle requires some angulation. Shape skis require less angulation than straight skis did, and sometimes no angulation at all is needed at the top of the turn, but generally some angulation is needed to prevent skidding.

Regards, John
post #41 of 46
I think another reason why banking is bad is that it gives one less options for recovery.

I've demonstrated this on a snowboard quite easily. When your banked and go over too far, there's no muscle power able to pull you back up.

But I'm having trouble convincing myself here at home with my experiments leaning against a chair. When I'm angulated, I can easily help myself get more upright simply by moving my hips. When I'm banked, if I try to move my hips back up, my head stays in the same place or drops (moving my body into a C shape) and I'm unable to get more upright.

Am I onto something here? Does the exercise work for other people?
post #42 of 46
To regress a bit ... "why is banking bad?"

Because so many people, especially young/mid-life males have watched racing on TV ....

They take an intro lesson and are convinced that the way to turn a ski is to "bank" the upper body. when I look down that line of students and see some "young bucks", I actually make a real strong point of getting it out of their heads that you can turn a ski with the upper body.

My chiropractor loves them though!
post #43 of 46
since Fox's vigilence seems to have taken a nap on this thread, I feel compelled to step in with a comment...

Physicsman, if it's just your wife who knows it (or, to be precise, what may or may not constitute an "it"), it ain't that perverse anyway

ok, delayed hijack ended. I'll listen to the serious stuff, it's very useful.
post #44 of 46
My vigilence was down the pub.
Unfortunately I wasn't.
But I did keep thinking of the "Weakest Link", where banking is good.
Or when you have a money grabbing SO who doesn't have access to your cheque book, banking is also good.
Otherwise, when it comes to skiing, banking is bad. You are creating an angle for visual purposes which reduces the effectiveness of muscle and bone structures in helping you through the turn.

How's that, PM?
post #45 of 46
Quote:
Originally posted by John Dowling:
...And it's not responsive to the original question, "why is banking bad?"..
You are absolutely correct that I elected not to answer that particular question he posed. I thought it would be better to respond first to his other question, "Can one be banking and angulating at the same time?", and make him aware that he stumbled into a situation where there is such a serious clash of definitions that seemingly opposite answers might be given to him.

Specifically, the reason I didn't answer his "Why is banking bad" question was that I felt he was clearly using the term "bank" in the common, colloquial way, meaning “Center-of-mass leaning”. Thus, his question really was, "is CM leaning generally bad", and the answer is obviously, “no”. OTOH, most instructors define “bank” as described below, and instead, will really be answering the question, "Is CM leaning without any angulation bad?", and hence, they will give the answer which you gave.

I would contend that the proper answer to his question (in the way I think he really meant it) is that, of course, CM leaning is not bad. It is something we do all the time at high speeds, except that on packed surfaces, to minimize skidding, we always add angulation while in an overall CM-leaned-over position.

> This is a new one on me. It's certainly not among the "most used approaches..."

In the paragraph you quoted, all I was trying to do was describe the typical shape of a racer going around a gate without using even a single one of the words, "banking", "angulation", or "inclination", whose common usages I find to be lacking, yet deeply entrenched. (Actually, I don’t have gripes about the definition of “angulation”, only the other two words, but decided to avoid using any of them.)

The sentence under discussion was: "Yes, you most certainly can combine a non-zero CM lean angle with extra edge angle obtained by contorting your body." There are two critical phrases in this sentence.

The first critical phrase is, "...you most certainly can combine a non-zero CM lean angle...". I don't think you can possibly argue that for the above hypothetical racer, the line between their outside edge and CM is off-vertical. That's all this part of the sentence is saying.

The second critical phrase in the sentence said, "...with the extra edge angle obtained by contorting your body...". Here, I hoped it was obvious that I was referring a couple of paragraphs above where I said, "...the banana (or C) shaped contortions of one's body commonly known as 'angulation'..". So, all this phrase is saying is that the above hypothetical racer is using angulation.

I feel that putting the two parts of the sentence together does indeed describe the usual body position of racers, and does so without using the words that I think are confusing to people not in the business. Unfortunately, it seems like my attempt to avoid the questionable terms produced something no less murky than what I am objecting to. Sorry.

I agree wholeheartedly about trying not to start up the old debate again, and would *really* be happy to agree to disagree. However, "Maxilovesthepow" asked a very specific question about whether one should combine banking and angulation in "good" skiing. Just asking the question this way gets right to the heart of the underlying definitional issue, so, unfortunately, I think this problem has to be at least momentarily touched on in order to help the guy out.

IMHO, his question clearly demonstrates that many ordinary folks (myself included) think of banking as any form of CM leaning (ie, with or without angulation), so its quite reasonable for them to ask could the two be combined. In other words, he is really wondering "Should I 'CM-lean' and angulate?", but instead, used the colloquial and widespread meaning of the word "bank", and instead, phrased his question as, "Can I bank and angulate".

Well, unfortunately, the standard usage by ski instructors is that banking is by definition "CM lean without angulation", so under this definition, its not even logically possible to ask if they can be combined. IMHO, the instructor’s definition of “bank” totally confuses most non-instructors, and that's why I attempted to answer this question of his without using any of the three words under question.

Tom / PM

PS#1 - BTW, when I mentioned that I was on the same side of this debate as a race coach, I hope it was clear that I was referring to Fastman (from Fla), not "Ski Coach" (Greg – originally from the USSR, now at Ski Liberty). I forgot that Greg was also a participant in the old thread.

PS#2 – Cedric and Fox ->

PS#3 - Sorry about the length.
post #46 of 46

Stable and Unstable Equilibrium

Physics man makes an interesting interpretation of the word "static" in the context of "being in balance" in his introduction to angulation. I'd like to expand on it a little with a useful concept.

Equilibrium (commonly referred to as balance) is a state where all forces applied to a body add up to to zero, both in direction and magnitude (as vectors or lines of force) so there is no acceleration.

A stable equilibrium is one where if a small disturbance takes place the physical system will tend back to a state of equilibrium ( a pendulum is a good example)

An unstable equilibrium is one where a small disturbance will lead to a state of further disturbance (think of a ball sitting on the flat top of a round hill or a pencil balance vertically on a finger).

With excessive banking one is in a state of unstable equilibrium (hence ice and hardpack are tricky) The CM is above the point of contact and gravity heads downwards!

With angulation the CM is closer to the point of contact with the snow and the flexing and natural elasticity of slightly tensed muscles will tend to correct a disturbance and neutralise it (because flex takes place partially across the vertically projected plane of the contact chord of the ski and this is the plane to which any centripetal force must be normal (perpendicular) in a carving situation.

In softer snow other factors apply - lateral ski motion is damped because of the snow platform described beautifully by physics man (and to an extent by the shovel of the ski), and there is better contact of base to snow thus naturally reducing disturbance.

This is why angulation is better on hard pack - it enduces a state of dynamically stable equilibrium, rather than the statically unstable equilibrium of the banking skier.

This makes faster skiing, more radical changes and more flexible response possible. Try telling an aggressive mogul (bumps) skier to bank his turns - hmmm

Hope you find this useful
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