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do i need to unweight? - Page 2

post #31 of 164
Dr. G--I'll allow that you use the term "unweighting" differently than I do. No problem!

But let's take a closer look at the action you described. Your words:

<BLOCKQUOTE>quote:</font><HR>The energy stored in my skis (because they are decambered) goes into an unweighting before I switch edges, why not just let that energy project my CM down the slope into the next turn?<HR></BLOCKQUOTE>

Regardless of what you wish to call it, the energy released as a ski snaps back from its reverse-cambered state cannot "project your CM down the slope." The direction of the force produced as that ski snaps back is perpendicular to its base, so its effect is only in a direction perpendicular to the ski base too (read up on Newton's Second Law of Motion of you're not sure about this).

So the direction of the force released by the skis snapping back from reverse camber can only be downhill if they are TIPPED downhill when it happens! Since you have described it--and I agree--as something that happens BEFORE you switch edges, you must conclude that the rebound from the skis can only project you UPhill, or at most, directly away from the hill.

To see how this works, here's a little experiment that you can either try, or just visualize. Support a ski between two chairs. Put a hockey puck on it, in the middle. Now push the ski straight down to bend it into reverse camber, and let go. Which way does the hockey puck go? I predict--straight up!

If you tip the skis at an angle and repeat the experiment, which way does the hockey puck go? If that ski doesn't launch that hockey puck in a direction perpendicular to its base (under the puck), every time, you've got some strange kind of ski! It's pretty predictable, isn't it? You can shoot that puck any direction you want by tipping the ski in that direction. You can NOT tip the ski one way, and shoot the puck ANOTHER way, can you? Intuitive, I suspect--if not, do the experiment.

Anyway, the sensation of "projecting your CM down the hill" with rebound results from the spring-back effect of your skis--and legs--combined with the direction your CM is already moving. The effect is, indeed, a light, floating senation as your body crosses over your skis and moves downhill into the new turn. You can increase or decrease this "springboard" effect as you choose--by extending your legs like you would to get big air off a jump, or by flexing to absorb the energy, as you would to avoid getting launched over a mogul.

And you can call it "unweighting" either way, if you want to. I don't.

Best regards,
Bob Barnes

<FONT COLOR="#800080" SIZE="1">[ November 01, 2001 08:17 PM: Message edited 1 time, by Bob Barnes/Colorado ]</font>
post #32 of 164
No offense just discussion.
Well we are pretty much donw the road. SO if you please back up a bit to the part where the ski is decambered and carving on it;s edge.
Now picture it in your mind Bob.
How do you think, you are going to release that edge?
post #33 of 164

You seem stuck on the idea that the skier must do something to release the edge of the ski. Its not necessary to release the edges just change them. And I can accomplish this change just by letting the path of my feet and my CM cross.

Just think of edge change and pressure distribution as the outcomes of a good turn rather than the causes.

post #34 of 164
Bob, a great description of the rebound effect with the hockey puck. Some of the initial descriptions were not completely clear to me, but the puck description is. This speaks volumes for instructors having many different ways to explain things to people with varied backgrounds/experience.

It seems like the forces involved with crossunder are also in line with your example.
post #35 of 164
Note that at the end of a turn, the bend of the ski tends to be concentrated at the rear of the ski. Therefore, the unbending action pushes the skis and feet forwards as well as up, which can help project the CM into the apex of the next turn, if the skier is dynamically balanced. Or it can seriously f*** up the next turn if the skier is not ready for it!
post #36 of 164
Yes the movement of the CM can actualy unwheight the ski ehough to change edge.
However I point out that the EDGED ski FULLY DECAMBERED, must have release in order to change edge.
IF you are swiveling or sliding you may not have an EDGED ski. The projection of the CM into another line casues an unwheighting.
Bob's point is that some may not CALL this unwheighting. However IT must be happening or there would be NO EDGE RELEASE.
Teh CM is initiated by the shoulders? or bu the upper body in some way. Eventualy the lower body partw will follow. Even with constant pressure the knees will have to roll over to the new upper body position (CM) at that moment, if for no other reason than the tibia or the flexors not being able to compress any longer there will be some give. Down, Up, Sideways, forward or back there will be some unweighting to flip the boards to the other edge.
ANd there must be an edge release to change edge.
I like looking at a good SNOWBOARD track. The carve is there and an edge change is much more obvious in hard pack as the width of the board is eveident.
Is ther unweighting, of course!
Get the PUCK out of there guys, you got to be pulling my leg! (or would that be unweighting?)
post #37 of 164
As a rebound skier from way back allow me to tell you how it feels to me. At the end of a turn, while the skis are still in reverse camber I allow my upper body to move downhill over the skis with increased angulation, so when the rebound happens, if I were to stiffen up, it would flip me downhill, kicking my feet uphill, but...

I don't use the rebound as a springboard, only to lighten me enough, without pushing my body upward, to allow me to swing my skis with retracted legs underneath my body to the opposite side for a fast edge set.

Rebound skiing makes one lazy, but I learned it eons ago when we started each turn with a "check" a fast displacement of the ski tail downhill to a hard edge set which put the skis into a reverse camber.

It is true that the skis bounced us uphill, but since the the check was done with a sinking motion and accompanied by heavy angulation and a pole plant well downhill, it had the effect of lifting our feet uphill, but since our pole was planted downhill stabilizing our body and keeping it from being bounced uphill it FELT like it projected our CM downhill, though, since we were off balance downhill, if allowed, the decambering would turn us upside down.

post #38 of 164
Dr.Go, I used to do some skijoring, as we were pulled by the horse on that long lanyard, to the left and then to the right, back and forth, going around bases like in a slalom, we never went up or down, no unweighting whatsoever, just rolled our skis over from one edge to the other.

We stayed down as you would in water skiing all the time. Why do I have to release or unweight when just shifting the weight left or right will roll the skis from edge to edge with my full weight on them all the time?

post #39 of 164
Exactly my point Dr. Ott!

Hey did you like my definition of "Christy"?

Did we not call them "SHOTSY", back in the old country!
post #40 of 164
Re: Hocky pucks being launched from skis in reverse camber.

A minor note - imagine (or actually perform) the experiment that BobB suggests with a ski whose base is parallel to the surface of the earth and watch the puck get launched vertically. Now, imagine that there is a 30 degree sloping hill under the ski.

Obviously, the puck still jumps straight up in the air, but observe that there is a substantial component of its motion in a direction perpendicular to the sloped hill.

In other words, if the puck represents the skier's center of mass, even with a ski edged as it would be at the end of a turn into a traverse (ie, pointing across the hill), the skier's CM still tends to be lifted away from the hill.

While this action certainly doesn't project his CM down the hill, I think its fair to say that this action could contribute to a feeling of lightness during a transition with rebound (that isn't absorbed by the legs), and will happen even if the ski is not flat to the snow at the moment of transition / rebound. This effect will be much more obvious on softer snow.

Just my $0.02,

Tom / PM
post #41 of 164

I don't think you get it. Bob said "Unweighting" (as I use the term) refers to a technique, an activity expressly intended to reduce the pressure on the skis to facilitate displacing or twisting them.".

Getting a ski from one edge to another does not require to unweight, as described above. Just like you don't have to unweight a bicycle as you change directions. However, should you ever drive a bicycle whose front wheel does not turn, you will either have to pivot that bike to turn (requires some serious forces, of course), or you have to UNWEIGHT the bike and then pivot it.

That is what Bob meant by unweigh. Not the releasing of the pressure required to keep a ski carving!
post #42 of 164
Thanks, Lucky--yes, we're finally coming around to the "cross-over/under" question. Indeed, if you look at Ott's description, it clearly shows one possible application. The rebound from the skis, which are tipped uphill as the turn ends, especially with a good old-fashioned edge-set "check," launches your FEET--not your CM--uphill. Your CM continues downhill as your legs flex (relax) and your feet shoot to the other side, and the cross-over/under move happens very quickly.

MilesB--good point that IF you load the tails of your skis heavily at the end of the turn, the rebound effect can have a forward component to it. But that's a big IF that also harkens to an older technique--exemplified by the exaggerated "jet turn" of the '70's. When skis couldn't bend as easily as they do today, tight turns sometimes required a lot of forward tip pressure to initiate (causing the tips to bite, but the tails to skid). This forward leveraged skidded entry then required a good dose of TAIL pressure at the end of the turn to stop the skid, set the edges, perhaps check speed, and create the platform to launch from into the next turn!

Back to the thread of "unweighting"--I came across this treatise on the subject in one of the true classic books of skiing--"The Handbook of Skiing," copyright 1981, by Karl Gamma. On page 184, in a section entitled "unweighting," Gamma begins, "All parallel turns rely on 'unweighting' as an aid to their initiation." Stop reading here, if you want a simple answer to the question "do we need to unweight?" But to understand the point, we must read on: "Unweighting works on the principle that skis with your full weight on them are hard to turn, because you are pressing them down onto the snow...."

The real key lies in the previous section (page 182) entitled "How turns are initiated": "The study of turn initiations is concerned with the problem of how skis can be turned out of the initial position and into a new direction" (emphasis added). He goes on to describe various ways of DISPLACING the skis, either both together or one at a time.

In his glossary, Gamma says this about unweighting: it "reduces the friction between the skis and the snow, and therefore makes turns easier to initiate. It is done either by a rapid up-extension or down-flexion (active unweighting) or by using natural bumps in the terrain (passive unweighting)."

Remember that in linked, carved turns, we are NOT trying to displace the skis in the transition, but merely to roll them to the new edges. There is no need to "turn them out of their initial position into a new direction," so no need for any of the activities Gamma describes as "active" or "passive" unweighting.

Best regards,
Bob Barnes

<FONT COLOR="#800080" SIZE="1">[ November 02, 2001 11:55 AM: Message edited 1 time, by Bob Barnes/Colorado ]</font>
post #43 of 164
Dr Go; You made this statement
>>Teh CM is initiated by the shoulders? or bu the upper body in some way. Eventualy the lower body partw will follow. Even with constant pressure the knees will have to roll over to the new upper body position (CM) at that moment, if for no other reason than the tibia or the flexors not being able to compress any longer there will be some give.<<
I am not sure whether you brain was working faster than you're key board and you mispoke about what you really meant or that this statment is literal. Initiating the center of mass with the upper body is not very efficient. If you're statement is literal then I would encourage you to look at CM initiation as a "feet first then up the kenetic chain to move the CM". :
post #44 of 164
L3SG, p. 89, 90
post #45 of 164
This is a cool thread and I've tried to coment twice today and yeaterady but got cut off by my modem. But I would like to throw a couple pennies in too. It is cool to see how this has progressed. Yesterday, I thought some people were missing it a bit but things have come around.

I like what you guys are talking about. Ott..nice one desbrining the old school "check" at the end of the turn to quickly slow your feet and trigger the CM to go up a touch and then down into teh next turn. Or the other transition you described where you keep "you full body weight" on the skis. I imagine that you are tlaking a long sweeping arlberg style turn where there is not a hole lot of builing and release of G's on the skis. You probably hev superb "touch" in your skiing. To take this a step further check move a step further, I believe you can get the same effect with a different movement pattern.

At the moment you "check" a quick speed differential takes place; you feet slow and your CM goes over the skis change edges. Right? So...on modern skis at a reasonable speed, a similar build up of G's happens in a well shaped turn. Say a GS type turn. You can use these G's and get a simlar effect of moveing the CM over the feet and into next turn by retracting triggered by relaxing to create the differential. The CM wants to go into into the next turn. Your legs on the skis and the shape of the turn hold it back UNTIL YOU RELEASE IT by relaxation/retraction. Then the CM flows into the turn just like it did above. The difference is that you trigger the move with less effort because you don't push aaginst the G's and it is silky smooth. And it works in varying snow conditions and speeds. With modern skis you don't even need to steer them.

I have to admit that I've never examinined it in this much detail. The idea of a speed differntial? Am I kidding myself? I think I maybe. It may not be a speed differential, but it is something like that. Actually, as I think about now and visualize it, I think it has more to do, again, with the G's and the release and build up with active movements. There is also some angular centrifugal forces which allow us to slow the release move and move it back up deeper closer to the falline.

post #46 of 164
OK, here we go again, Devils advocate and all!

SO the Bike thing keeps coming up and it is a good look at what we are speaking about.
Ever watch the ovals? These guys really get out there on those bikes. One knee almost skimms the ground. Tires never leave the ground. As they round the corner there is going to be a moment that they will move mass from one side of the bike to the other. We are talking ROUND tires here not flat skies. However with the Gs there will with out a doubt be an instant that they are like weightless.
Same in ski racing same in short radius turns on your favorite slope.
The pysics demands it, one can not load up the ski and not expect it to unload.
Now call it what you want. We spent alot of money on or DEMO team and we just HAVE to HAVE our own method here in the States. But a tomato is a tomato, or tomatoe Mr. Quail. (you say tomatoe I say tomaaaato)
Call it what you will there is an instant of weightless ness which will occur.
It is truly one of the great feelings in skiing.
Hope you don't miss it!

L3SG, p. 89, 90 (Level three pages addressing pressure and steering)
Just in case an Examiner is reading this we want to impress 'em!
post #47 of 164
Dr.Go the study guides are a bit dated in their focus and I tend to cringe at some of the things that are currently in print. PSIA has agreed with this and is why they are trying to rewrite everything they have out there. Most of their literature predates shape skis.
That floating feeling of unweighting the skis has diminished greatly in my skiing to the point where I only feel it in short retraction turns. I have even largely lost this floating feeling in bumps. This is the one thing that I did not want to give up. You are right that it is a great feeling but so is the solid control of being on edge constantly with flow from turn to turn. The shear excitement of the awsome precision felt without that floating feeling. That floating feeling means you could have an earlier edge and with it comes awsome precision. [img]smile.gif[/img]
post #48 of 164
Dr...Dr..I absolutely, positively concur that there is a build up and a release of G's linking turns. No question at all in my mind.

It seems the 10 million dollar quetion is what are the most efficient movements to connect the turns and trhereby manage the build up and release of the inherent forces of ski turns. I have my own thoughts on this. I'm curious about other's thougts on the specific movements to do this.

think snow and world peace,
post #49 of 164
Oh man Eski. Paragraph three last sentence.
>>With modern skis you don't even need to steer them.<<
Thems are trigger words that long time forum guys like me instantly see for the're shear ability to bring out the passion :
I won't touch it.

<FONT COLOR="#800080" SIZE="1">[ November 02, 2001 07:40 PM: Message edited 1 time, by Pierre eh! ]</font>
post #50 of 164
With all these differeing opinions I wonder if any of you can ski.

In the olden days we didn't worry about decambered skis, they stayed decambered even after we took them off. [img]smile.gif[/img]

post #51 of 164
Hey Pierrs eh...maybe I should not either.


I knew that would be a real attention grabber! I almost pulled it out...but...I beleive it to be largely true!


post #52 of 164
I was wondering when you boys were going to notice Eski's comments about steering.

Yo Pierre,

I was going to offer you a ride in my boat, but sorry, it's full. In fact, I'm going to need a damn yacht!

post #53 of 164
Yah know, I gots to wonder about abandoning the PSIA correct definition of steering in a practical sense only. Steering has been so abused and misused as to have an entirely different meaning in actual practice. I am not willing to throw out the correct defintion but when I say "steering" to a student, that student will almost invariably get the idea of pivoting/twisting a flat uphill ski instead of constant guiding of both skis. In the practical sense I give up the fight and join HH but I will still adhere to the correct defintion as set forth and soforth in ATS.
I like Ydnar's saying "the outside ski is the ride ski and the inside ski is the guide ski" less confusion that way. :
post #54 of 164
Bravo Pierre eh!

I think you just summed up the popular conception of steering (pivoting the skis when flat) and provided a one sentence alternative which to me is way more palitable for a non-steering Pro like me and a few others. Nice one.

At the same time, I still think that too much emphasis on steering or rotational guiding of the feet through the arc can be difficult for people to master and maintian balance and can still lead to skidding on firm snow and trouble in powder and soft snow.

Also it could be argued that new skis do not need much of this type of guidance to create nice round turns. Therefore, I would put forth the idea that it is the lateral guiding (edge angle of the skis) and weight distribution between the skis that plays a more significant role in creating sweet, linked turns.

post #55 of 164

I want to understand. Are you talking about the point in time when the skis are not producing a force that you can feel? When the ski is flat it produces no force for you to channel into moving your CM but I certainly haven't unweighted it. You could say that the ski has unpressured itself. But if this feeling of a lack of pressure lasts for more than an instant then you aren't engaging your new edge. And by one deffinition a turn doesn't start untill you engage your new edges.

post #56 of 164
Why not just call it the stance foot and the free foot? It's the best definition I've seen -- from any point of view.

Oh, but that'd mean we'd be using some of HH's vernacular and we can't do that now can we?

Well, I can certainly think of a word for that kind of thinking - crapola!
post #57 of 164
Hi Pierre eh!

I agree with your post regarding steering and the many common misinterpretations of the term. But I am not prepared to abandon its use!

Frankly, I think it is instructors only who have misused, and who may continue to misuse the term "steering." I think students who have not yet been misguided come with a clear and appropriate understanding! "Steering," as most "lay-people" use it every day, describes the action well. "Holding the wheel" is what it means in a car--not spinning it! Guiding a bicycle, or a sailboat, or whatever, would commonly be considered "steering," wouldn't it? As I've often said, I steer a car even when I'm going straight, and I think most other drivers do the same. I do the same with my skis.

It is only a few ski instructors who seem to think that steering implies gross pivoting/twisting movements or throwing the outside ski into a skid. HH has certainly not helped this--he's the only one I know who adamantly insists that steering means twisting the outside ski. He's the one who has made it a popular (or unpopular) notion. He's right when he says "don't do it" in general, but he's wrong to suggest that most of us ever said otherwise!

The "official" PSIA definition of steering, from the most recent ALPINE MANUAL, is simply "the use of muscular actions to direct the path of the skis" (pg 149). These words are consistent with the "common" definition, reinforced by THE AMERICAN HERITAGE DICTIONARY: "To direct the course of" or, perhaps even more appropriate, "to guide by means of a device such as a rudder, paddle, or wheel" (or, perhaps, a ski!). The dictionary suggests that "guide" is a synonym. Where does "twist" or "throw into a skid" come in here?

"Steering" is extremely important in skiing, just as holding the wheel is important in driving. It is an enormous disservice to skiers--and to PSIA--to first redefine it as something undesirable, then to suggest that, despite evidence to the contrary in plain written English, PSIA subscribes to this "wrong" definition. But the most harmful disservice to skiers is to then throw out the whole notion, based on these insidious fabrications!

As I have often said, "steering" means simply "using muscles to control the direction the skis point." This most basic, essential skill is almost a truism! If you like the way they're pointing, then just hold the wheel and don't "do" anything. But if you don't, it would be pretty stupid not to do something about it just because some idiot said "it's wrong."

And as with that car's steering wheel, what you do depends on your skill and experience, but includes everything from the most subtle, gentle, guiding movements to throwing the wheel hard in an emergency. Woe be to the skier who is afraid to do these things when needed because he's afraid to offend some instructor who has steered him wrong.

Best regards,
Bob Barnes
post #58 of 164
<BLOCKQUOTE>quote:</font><HR> Why not just call it the stance foot and the free foot? It's the best definition I've seen -- from any point of view. <HR></BLOCKQUOTE>

Why not? Because it implies that I'm always standing on one foot, and that the other one is always free--an outdated notion, at the very least. Because it only fits into a very small subset of movements, based on a complete weight transfer--that's why not! I hate to think that I have to stand on one foot just to know right from left!

Don't forget that we get used to any definition that we use regularly. We start to accept it, and use it, and know exactly what it means to us, even if it might have an entirely different--or perhaps NO--meaning to someone who hasn't been indoctrinated by the same sources! "Free foot" and "stance foot" work fine, once you know what they mean. But you have to learn the meaning of the expressions first--the words themselves need explanation.

As long as we get the chance to define how we are using terms, it really doesn't matter what terms we use! "Stance foot" and "free foot" work, once you know what they mean. But they don't work any better than the common "Bert" and "Ernie" that many kids' instructors like to use, and that most kids understand way better than "stance" and "free"!

I like the terminology I heard Elan's Bill Irwin use once. He said "A turn is like a pie. We ski around its edge, with one foot on the crust, and the other in the filling. So we have a 'crust' foot and a 'filling' foot." As silly as this is, it works (once it's explained) and isn't handicapped by the need to be standing on one foot just to describe which is which!

To me, still the simplest, clearest terminology, the words that need the least explanation, remain "inside ski" and "outside ski" of the turn. Universal, simple, and as long as we're turning, always applicable! If we aren't turning, we have "uphill" and "downhill" skis--also pretty clear--or simply "right ski" and "left ski." What could be simpler?

Best regards,
Bob Barnes
post #59 of 164
Its amazing how we as skiers become almost religious in the way we ski and the words we use to describe it. We need to become more open to all the options available to us.

There are four basic types of behaviors that result from blending all the different movment patterns in different situations.

1. we can straight run
2. we can pivot our skis
3. we can carve with our skis
4. we can blend the above

No one behavior is appropriate for all situations. The most skilled skiers are the ones who can blend the movement patterns to achieve the desired behaviors. I can think of many a situation where a pivot followed by a skid saved my #ss. Not as stylish as linked carved turns but it got the job done.

If we become dogmatic in our approach to technique we tend restrict our skiing to situations that match our technique. If this happens, much of the experience of skiing will be lost because we will view parts of the mountain as unenjoyable.

Don't limit yourself!
post #60 of 164
That's way to much information. A natural athletic stance with a constant adjustment for balance seems to work. Your brain will tell you when it isn't right. If it feels good do it.
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