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Tell him what you think! (MA Request) - Page 2

post #31 of 48
Quote:
Originally Posted by tdk6
Ok, my misstace, I did not really mean twin tip skis but wide douple tip skis anyway. If the Dobermann boots are 150 flex they must be pritty stiff!
Your spelling is atrocious, what are you, Finnish or something?
post #32 of 48

Awesome turns!

OK--finally got everything downloaded and had a chance to watch it.

First of all, it is extremely good skiing, DoubleDiamond. Most people would be thrilled to rip carved turns like that, and you should be proud of the way you ski. But great skiers are never satisfied! In the spirit of continued improvement, here's my analysis of the two runs on your video.

It is pretty clear from the video that your intent is to carve clean, high-G turns. If that assumption is correct, you're succeeding!

I like your stance overall, and particularly the discipline of your upper and lower body. Those who are currently arguing about "countered vs. square vs. rotated" as well as "inclincation vs. angulation" in other threads would do well to watch your alignment. You show a natural, functional blend of movements that keeps your movement options wide open and allows your body to move and deal with the stresses of those high G-force turns efficiently and safely. Notice that Your legs rotate in your hip sockets, beneath your pelvis and upper body, similarly to the way a snowmobile's skis turn beneath its chassis. This leg rotation, which is subtle in these highly carved turns, steers your skis into a slightly "countered" orientation to your upper body (your skis point slightly to the right of your pelvis and shoulders in a right turn). The inclination ("tipping") of your pelvis also contributes to a little countering and lead of the inside ski, as it requires your inside leg to flex more deeply than the outside leg ("long leg-short leg"). This is all good!

If anyone is having a hard time seeing what I've just described, observe one clear sign. Stop the video almost anywhere and look at DD's position. Imagine a line drawn across his ski tips. Note that the inside tip almost always leads the outside tip slightly. And note that lines across his knees, hips, shoulders, and (usually) hands are almost always parallel to the line across the ski tips, at least in the fore-aft plane. That is to say, in a right turn, DD's right tip leads slightly, as does his right knee, hip, and shoulder. Some people refer to this as a "strong inside half," although I've never cared for that description much. See the bottom image in the illustration, of Jerry Berg showing these same parallel relationships.



In any case, this "parallel" alignment results from active legs working beneath a disciplined upper body. It is the prime sign of "leg steering," meaning he guides his skis almost entirely with his feet and legs, rather then twisting them with movements of his upper body. (These upper body movements include classic "rotation" and "counter-rotation." With "rotation," part or all of the upper body rotate first into the turn, then pull the skis around, resulting in a "rotated" orientation--shoulders facing into the turn [middle image in the illustration]. With "counter-rotation," the skis and lower body--hips down--twist one way as the upper body twists the other way, resulting in a highly countered [twisted] orientation--shoulders facing way outside the turn--top image in the illustration). DoubleDiamond uses these upper body rotary mechanisms only sparingly, and with great discipline, guiding his skis almost exclusively with his feet and legs. Again--it's good!

You are nicely demonstrating "active leg steering" in a highly refined way. There's a lot of confusion and misconception about what this term means, as you've probably noticed. What I mean by it is that, as I described, you continuously manage the direction your skis point, using your legs. It does not imply that you are twisting them excessively--or at all! Like that snowmobile again, it is the equivalent of keeping your hands on the handlebar, guiding the skis as much as needed--but not more--including making sure they do not turn when you don't want them to. You steer a car even when you're going straight, don't you? In these carved turns, you don't need or want to twist or redirect your skis at any point, least of all the transition (when the edges are not engaged). And you don't! Nice!

As I mentioned, I also like the combination of inclination and angulation you show, DD. Some instructors might suggest that you are "banking" too much (letting your shoulders tip into the turn). But what you are showing here is a highly functional use of your tipping options, in my opinion. You create a lot of edge angle just through inclination (tipping into the turn for balance) and use angulation as needed to control and adjust your edge angle. No need for any more! Another strength is that your angulation movements tend to work from the feet up, with strong focus (usually) on tipping the inside foot. More good!

So--lots of good stuff going on there, which explains the overall great skiing.

Where should you look for improvement, then? Let's go there in the next post.

Best regards,
Bob Barnes

post #33 of 48

Prescription for change

Here are a few other observations that jump out at me from the video, that we should explore.

First, notice that you tend to break at the waist, with a lot of forward lean of your upper body. Even when you are "tall" and relaxed, your shins tend to be a bit more upright than your spine. This suggests to me two things: that you are trying hard to keep some pressure on your boot cuffs, and that your boots may be a bit too upright (and some might say too stiff, but I like stiff boots--as long as they're set up right). Do you tend to get thrown into the back seat more than you like, or bucked forward at the waist, when you hit a big mogul?

I'm sure that you do, because it's happening even here, in the "virtual bumps" of these carved turns. Notice that you tend to pop "up" at the end of most turns, and that your downhill tip (especially the right one) often comes right off the snow. Looking farther back in the turn, notice that as you flex lower to create higher edge angles, your hips tend to drop down and back. And that in that transition, when you relax and stand a little taller, your hips still tend to remain well behind your feet as you reach forward with your upper body. We need to explore the cause, and the effects, of these movements--I think they hold the key!

Finally, notice that as you enter the new turn--right after that moment when your downhill ski lifts off the snow--your stance often widens slightly, sometimes with a divergence of the inside tip, and you get a lot of pressure on the inside ski (losing pressure on the outside ski). It appears that you are falling too much to the inside too early in the turn. We'll take a look at the implications of these movements as well. . . .

Skipping to the conclusion, my suggestion for your "SMIM" (single most important movement) or, as I like to put it, your "FIT" (First Important Thing--sometimes it's not a movement, but a tactic, or other focus)--is to ease the pressure off your boot tongues, freeing your ankles to move more easily, and allowing you, ironically, to move more continuously forward. I'm guessing that you are trying to "get forward" most of the time, trying to keep pressure on those boot tongues. I recommend that you give yourself permission to get off them--even allowing yourself to feel the backs of your boot cuffs now and then.

Heresy!? Decide for yourself--I only make recommendations! I realize that conventional wisdom, reinforced by the constant berating of race coaches and instructors alike to "get forward get forward get forward," suggests that losing contact with your boot cuffs is a bad thing. But I urge you to look closely at top skiers, from World Cup alpine racers to pro mogul competitors. Notice that they--like you--often get their hips way behind their feet but that, unlike you, they usually encourage it without trying to push on their boot tongues. It looke to me like you're trying to keep pressure on those boot cuffs all the time.

Look at the two animated sequences of World Cup racers below, along with some of Ron LeMaster's excellent montages on his web site (ronlemaster.com), and at this montage of a pro bump skier at Copper Mountain (and note the similarities, along with the obvious differences!):




The fact is that we DO need to move continuously forward, driving our skis through the turn, and especially driving forward and across the skis out of the old turn and into the new turn at the transition. And it appears that you're trying to do that. But consider that moving forward and being forward are two different things, and that they often conflict with each other. You can't go somewhere when you're already there, and you can't move forward when you're already pressed up against the wall of your stiff boot cuffs! Indeed, the act of pressing forward on your boot cuffs causes the boot cuffs to press backward on you! And that's the problem. You need to get off your boot cuffs so that you can move forward!

Why do I think that? Back to those observations. . . . I see the problem occurring in two areas. The first is early in the turn, when you first attempt to create high edge angles. That's when you tend to drop your hips down and back, blocking your forward movement. (You see this more clearly in the "Arc y Sparky" clip.) It's virtually impossible to move forward (in relation to your feet) while flexing lower, when your boot cuffs are pressing back on you! This is why your hips get pushed back.

The second and more critical area is the transition. Because your continued efforts to get forward keep you pressed firmly up against your boot tongues, you tend to "crash" into them hard at the end of the turn. Just when you need to release everything and let your skis continue to run forward as your body crosses over into the new turn, everything just stops moving. Momentum dies here, and instead of a smooth glide into the new turn, your body gets pushed "up." This is the cause of that downhill ski lifting off the snow. (I don't know if this lift of the downhill ski is something you're intentionally encouraging as well. The result is the same, either way.)

So I suggest that you back off from those boot cuffs early in the turn, and make sure you don't run into them as you flex lower and drive forward. As you come through the bottom of the turn, keep driving your body forward toward the transition (moment of edge release and crossover at the end of the turn). The moment you feel your shins contacting the boot tongues, rather than letting them stop your foward motion by pushing you back, let your feet move forward beneath you instead. This is the magic moment when your feet and body are traveling in clearly different directions, and you're letting them. This is the crossover. By allowing your feet to get ahead of your hips in the fore-aft plane, you also allow your hips and your body to move downhill, across your skis and into the turn. In other words, your hips are well behind your feet in the fore-aft plane, but they're moving ahead of your feet into the turn! It may look as if you're "sitting back" in the transition, but you really aren't (and there should not be any extra pressure on the backs of your boot cuffs either). As soon as your skis turn down the hill, everthing will look and feel "normal."

Take a look at this sequence of Laure Pequegnot, winning the slalom at the World Cup race in Copper Mountain--it's pretty clear here!




And then look at this sequence of Kristina Koznick, in the same gates. She misses the move somewhat in that second left-to-right transition Notice how her forward momentum just stops when she hits her boot cuffs. Her hips stop moving, and her torso gets bucked forward and up. And she may well have lost the race right there!



Look familiar?

So how does this all relate to that fall to the inside early in many of your turns? Here's how I see it. Your boot tongue pressure interferes with your downhill momentum at the transition, as described. You move "up," over your uphill ski, and your downhill ski lightens as the tip lifts off the snow. This causes you to start "falling" back down the hill, almost sideways into the turn (your forward momentum has been considerably lessened by the boot tongue pressure, remember.) So you end up too far inside, too early in the turn, and your skis aren't carving effectively enough at that point to "catch" you. So you have to open your stance by pulling your inside ski underneath you, literally to keep from falling over or having to twist your outside ski ungracefully to tighten the turn. Your outside ski loses pressure for a moment, further degrading--or at least, delaying--the carve.

You can see this most clearly in the "Arc y Sparky" clip, especially in the first couple turns before you get up to speed. It may be further exacerbated by a conscious attempt on your part to "get early edge" and start carving too soon, before the forces of the turn allow you to sustain pressure on the outside ski. Do you? If so, be a little more patient. "Float"--stay "light"--a little longer, before trying to "pressure" your skis and bend them into a carve too early in the turn.

At your level, all these suggestions refer to very subtle, but very important, changes. Again, overall, your skiing is excellent. Don't try to change too much! For what it's worth, I think you skied better in the "Arc2" clip. Note in particular the transition near the end, beginning at around 16" into the clip. It's awesome!

There are a few other things, but I would consider them minor, effects of the big issues, or perhaps minor alignment (boot setup) issues. As I noted, it is possible that those uber-stiff Dobermans (I ski the same boot, by the way) are too upright for you. This may be addressed by increasing forward cuff angle, installing the shim on the back of the inner boot, or increasing "delta angle" by shimiming your bindings, using different bindings, or installing thicker plates under your heels. It could also reflect an insufficient range of dorsi-flexion in your ankles, which might be addressed by installing heel lifts. In any case, it's something best left to a real boot expert to find the best solution.

You may also be slightly--and I mean slightly--underedged, which could reflect a footbed that doesn't provide sufficient support or accommodate a likely tendency to over-pronate. Again--a job for a top bootfitter. (I know you've seen some of the best, but there's always room for a second opinion, and footbeds do break down.)

Anyway, I'd focus on the biggest things first. If you have been trying to press against your boot tongues, back off! Ski a few runs trying to keep the pressure from ever building on the tongues (but without losing contact with them either). Try to stay "neutral" between the front and back cuffs. Even try a run or two intentionally trying to remain in contact with the backs of your boots, to experience the contrast--especially through the transition.

Explore the thought of "driving" your body forward throughout the turn--which is very different from trying to press forward on your boot cuffs! It is similar to the thought of trying to run or skate down the hill through the turn. When you run, you're constantly driving your body forward, but never trying to "get forward"--you need your feet to keep up! And your skis will keep up. As you drive your body forward, it will feel like the afterburners kick in on your skis! It will add the next dimension of power to your skiing, taking those already-clean carves to the next dynamic level.

Enjoy!

Best regards,
Bob Barnes
post #34 of 48
PS--one quick note--to synchronize the two World Cup animations above (Laure Pequegnot and Kristina Koznick), let the page load completely, then click on another page--any page will do. Then click on the "back" arrow on your browser to return to the original page. The two racers should now be synchronized. Works for me, at least! And merely "refreshing" the page doesn't do it.

Once they're in sync, it is easy to see how much time Koznick lost after her little bobble!

Best regards,
Bob
post #35 of 48
Bob,

Are you striving for the cuff pressure to be neutral throughout the entire turn? Is it the same for both the inside and outside leg? Does it depend on the turn? Is it an intent, more/rather than an outcome?

It seems to me that as I pick up speed, and start getting deeper into turns, that I end up with additional cuff pressure building on the inside leg as it shortens and the ankle and knee drive into the turn. While the outside leg is more of a gotta keep using that ankle to keep moving forward while it lengthens. The ankles get no rest though, and hopefully it all unwinds to neutral when the skis release. I'd describe this pressure as progressive with the edge angle in continuous linked turns - say, medium radius performance turns for example.

Rogan and Shanzy were smacking me for having both feet flexing/extending together, so in trying to focus more on one lengthening and one shortening I started to sense more of a squeeze on the inside leg.

Chris
post #36 of 48

Yah--it depends!

Quote:
Are you striving for the cuff pressure to be neutral throughout the entire turn? Is it the same for both the inside and outside leg? Does it depend on the turn? Is it an intent, more/rather than an outcome?
Chris--as usual, you bring up some great questions. Short answer--yes, it depends on the turn. But you know well my aversion to short answers!

Like so many other things, pressure management on skis is a tool, and a skill. It is not a "technique" that involves a specific set and sequence of movements that is "right," while other ways are wrong. The only real way to answer your question is to explore the effects of various options. Only once we understand the effects, can we determine whether a particular movement is right or wrong. And then the answer is simple--either it produces the desired or needed effect, or it doesn't.

So, yes--it depends on your intent!

Remember that skis perform differently depending on where the pressure (force) on them is centered. They have a "sweet spot," which varies somewhat from ski to ski, which distributes pressure such that the ski bends into the roundest possible arc. If your goal (intent) is to carve the cleanest possible arc, at any point in the arc, you need to center the pressure on your skis over this "sweet spot."

The sweet spot!

Again, if this is your intent throughout the turn, then this need does not change throughout the turn. The ski doesn't know or care what part of the turn you're in--it bends only in response to the forces applied to it. (And it doesn't care whether it's the inside ski or the outside ski, either.) The still common notion that you need to increase relative (to the rest of the ski) tip pressure at the beginning of the turn, and increase relative tail pressure at the end, stems from the old need to get a ski skidding to start a turn, and to stop it from skidding to finish a turn. We still need to do that in many situations, but clearly not when the intent is the pure, clean carve.

I should point out that the "pure, clean carve" does not necessarily have to be "round." We have several tools we can apply to change the radius of a turn without necessarily increasing skidding. Increasing the edge angle on the slope (assuming sufficient pressure exists to bend the ski) will tighten the radius even on the hardest ice you can hold on. And in "normal" conditions (i.e. not rock hard), increased pressure will also cause a ski to bend into a tighter arc.

It's only when you need to change the shape of the arc--from round to something else--that you need to "lever" the ski--that is, to move the center of the pressure you apply forward or back of the sweet spot. Changing the ski's shape will also affect the shape of the turn (size of the radius), but only at the expense of that pure carve. Not necessarily a bad thing, unless, again, your goal is a pure carve!

If your intent changes--which it can do from run to run, turn to turn, or even moment to moment in a turn--your need for managing pressure changes also.

While this theoretical "pure carve" may sound like something desirable, I contend that in most real skiing situations--including racing--it is not as important as many think it is. Pure carving is a luxury, a game--albeit a very fun one. The needs for either speed control (braking) or precise line control both trump "fun" in the hierarchy of importance, whenever they arise. So no, I do not necessarily "strive for the cuff pressure to be neutral throughout the entire turn" very often. I only do it when I'm after that pure, theoretical, perfect carve! Although I should add that, when I need to reshape a turn, I usually want to do it with minimal increased skidding, so tipping and increasing pressure are my first tools, with leverage and active twisting coming in only as absolutely needed. (Which they often are!)

I should also add, to prevent possible confusion, that the outcome of maintaining pressure constantly over the sweet spot (or any spot, for that matter) is definitely not the same as "staying in one position." Because of the dynamics of ski turns--the constantly changing speeds, snow conditions, slope angles, and orientation on the slope--maintaining pressure on one spot on the ski requires often huge amounts of movement. Like keeping your balance on one foot in a moving bus (without holding on), it's quite a challenge, and no static "position" will accomplish it. Specifically, as you start a turn, your skis turn down the hill. That means that they both tip down and gain speed. So your body (center of mass) must move often dramatically forward, just to keep your balance over the sweet spot. And even more forward if you want to increase relative tip pressure at the same time.

But, if that "forward movement" causes you to press forward and down on your boot tongues, you are levering your ski tips. It's good or bad if its effect is what you intend, or not!

**********************

As for the inside-outside leg question, like I said, your ski doesn't care which ski it is. We must manage the pressure accurately on both of them. If you increase the bend in one leg, but try to keep that foot still right under your hips, you will certainly increase the pressure on your boot tongue. So--don't even try to keep that foot under your hip (unless you need to lever the tip). Let the foot move forward as much as needed (not more)! Inclining (tipping) the pelvis into a turn, which requires/causes the "long leg-short leg" thing, is one of the two major causes of inside tip lead. (The other cause is the rotation of the legs in the hip sockets.) You must allow some tip lead to develop. Otherwise you aren't giving yourself permission to make some fundamentally critical movements!

Keep in mind, though, that not all turns require "long leg-short leg." Any time your pelvis remains "parallel" to the slope--which happens when you use strong hip angulation--both legs will remain the same "length" (same degree of knee flexion). "PSIMAN" is a great example of this--his legs can't bend!



Most "real" turns, of course, do involve inclination of the pelvis to some degree.

All movements produce changes in "position." Unfortunately, many skiers--and instructors--tend to focus more on these characteristic positions than on the fundamental movements that cause them. Do not mistake "positions" for fundamental movements! Positions are almost always, as you suggest, "outcomes," rather than ends or focuses in themselves.

Best regards,
Bob Barnes
post #37 of 48
Quote:
Originally Posted by Bob Barnes/Colorado
I should point out that the "pure, clean carve" does not necessarily have to be "round."
Bob,

When we have skis that have different tip and tail widths, does this mean that a pure clean carve can not be round? It would seem that such a ski must have different turning radii at the tip and the tail. As such wouldn't there have to be some skidding of some of the ski to get a round turn to happen? My suspicion is that most such skidding, if it were so, would be imperceptible to the untrained eye. Am I on the right track?
post #38 of 48

Have you ever had a question -you could not boil down to IDT?

Thanks for the long answer, Bob

Quote:
Originally Posted by Bob Barnes/Colorado
As for the inside-outside leg question, like I said, your ski doesn't care which ski it is. We must manage the pressure accurately on both of them. If you increase the bend in one leg, but try to keep that foot still right under your hips, you will certainly increase the pressure on your boot tongue. So--don't even try to keep that foot under your hip (unless you need to lever the tip).
Seems rational that as turn forces increase and are borne more by the outside leg (bending this ski more), additional pressure/tension by leveraging the inside cuff and/or at higher edge angles closing the ankle to guide/pull the tip into the turn, could have merit and/or could be a desireable result.

The good new is ...I get to go skiing this week! So I can go experiment with it! I'll certainly experiment with allowing that foot to move forward - as much as needed!

Thanks,

Chris
post #39 of 48
I just typed a really long reply and lost it when the system auto-logged me out. DAMMIT! :

I'll give it another shot later, time to hit the gym.
post #40 of 48
Bob-

First of all, thanks for taking the time to write such a detailed, in-depth analysis of my skiing. I really appreciate it, as I'm sure you have things you could be doing that involve getting paid. Your donation of time to the forum is really appreciated.

With regards to your first post, thanks for the compliments . My intent was indeed to carve high-g turns. The video was shot knowing I was going to post it, so I was trying to look good. I'd probably look better and more powerful on my slalom sticks than on those metrons, fwiw. (They were demos with a miserable tune on them) The intent was something like an SL race turn, as you might have guessed when I pretended there was a fallaway gate towards the end of the arc2 clip.

Anyway, I'll tackle parts of what you said one at a time.

Quote:
Originally Posted by Bob Barnes
First, notice that you tend to break at the waist, with a lot of forward lean of your upper body. Even when you are "tall" and relaxed, your shins tend to be a bit more upright than your spine. This suggests to me two things: that you are trying hard to keep some pressure on your boot cuffs, and that your boots may be a bit too upright
I have noticed this, and I don't believe that it is a function of the boots. The dobies are indeed upright, but I have the spoiler in, so that helps. FWIW, I did the same thing when I was in Diablo race 130s last year, which have tons of forward lean.

Quote:
Originally Posted by Bob Barnes
Looking farther back in the turn, notice that as you flex lower to create higher edge angles, your hips tend to drop down and back.
I have noticed this, others have pointed it out as being a problem as well.

Quote:
Originally Posted by Bob Barnes
I'm guessing that you are trying to "get forward" most of the time, trying to keep pressure on those boot tongues.
This is totally right on. I am always trying to keep pressure on the tips, with my knees over my toes. It stems from being used to race stock skis that require tip pressure to bend into an arc. I like to be able to play with the radius by bending the skis dramatically.

Quote:
Originally Posted by Bob Barnes
The fact is that we DO need to move continuously forward, driving our skis through the turn, and especially driving forward and across the skis out of the old turn and into the new turn at the transition. And it appears that you're trying to do that. But consider that moving forward and being forward are two different things, and that they often conflict with each other. You can't go somewhere when you're already there, and you can't move forward when you're already pressed up against the wall of your stiff boot cuffs! Indeed, the act of pressing forward on your boot cuffs causes the boot cuffs to press backward on you! And that's the problem. You need to get off your boot cuffs so that you can move forward!
This makes sense in lieu of your WC examples. My knees being driven forward seems to prevent me from extending and getting the hips forward.

Quote:
Originally Posted by Bob Barnes
Explore the thought of "driving" your body forward throughout the turn--which is very different from trying to press forward on your boot cuffs! It is similar to the thought of trying to run or skate down the hill through the turn. When you run, you're constantly driving your body forward, but never trying to "get forward"--you need your feet to keep up! And your skis will keep up. As you drive your body forward, it will feel like the afterburners kick in on your skis! It will add the next dimension of power to your skiing, taking those already-clean carves to the next dynamic level.
I see what you are saying, but my question is how do I bend the tip of a race stock ski enough to make a good turn without cuff pressure?

Quote:
Originally Posted by Bob Barnes
t's only when you need to change the shape of the arc--from round to something else--that you need to "lever" the ski--that is, to move the center of the pressure you apply forward or back of the sweet spot. Changing the ski's shape will also affect the shape of the turn (size of the radius), but only at the expense of that pure carve. Not necessarily a bad thing, unless, again, your goal is a pure carve!
How is this not a pure carve? When one tightens the radius of a ski by bending it dramatically (as I am wont to do), the ski is still carving, it is just deeply bent.



Thanks again for your time Bob.

(This response is less well-developed than the one I lost, but what can you do...)
post #41 of 48
(Continued due to the stupid editing limit)

Quote:
Originally Posted by Bob Barnes
The second and more critical area is the transition. Because your continued efforts to get forward keep you pressed firmly up against your boot tongues, you tend to "crash" into them hard at the end of the turn. Just when you need to release everything and let your skis continue to run forward as your body crosses over into the new turn, everything just stops moving. Momentum dies here, and instead of a smooth glide into the new turn, your body gets pushed "up."
Again, this push up is definitely something I have noticed, especially on longer GS skis. In its most dramatic form, as it took when I was testing some LT:11s, this push up combines with the huge amount of energy stored in the deeply bent ski to shoot me into the air in transition. Fun, but sometimes hard to manage, as far as getting to the next turn without falling into the back seat.
post #42 of 48
Hi DoubleD--thanks for the point-by-point reply! Sounds like your understanding and awareness of your own skiing and movements is already pretty spot on!

Just one note regarding your last question:


Quote:
How is this not a pure carve? When one tightens the radius of a ski by bending it dramatically (as I am wont to do), the ski is still carving, it is just deeply bent.
(You were referring to the following statement by me: "It's only when you need to change the shape of the arc--from round to something else--that you need to "lever" the ski--that is, to move the center of the pressure you apply forward or back of the sweet spot. Changing the ski's shape will also affect the shape of the turn (size of the radius), but only at the expense of that pure carve. Not necessarily a bad thing, unless, again, your goal is a pure carve!")

My point is simply that, if the ski is pressured anywhere other than its "sweet spot," the arc it bends into will not be as round. In other words, levering forward on it will, as you suggest, tighten the bend of the tip section of the ski, but only at the expense of straightening out the bend of the tail section. As a result, the ski will carve a tighter radius turn (as long as you don't lever the tip so extremely that the tail loses its grip and washes out), but the carve will not be quite as clean and "pure" as when the ski is pressured in its sweet spot. That's not to say that it won't still be useful, in some situations!

I would urge you to explore (that is to say, question!) the meaning of the "conventional wisdom" you imply with this statement:

Quote:
I am always trying to keep pressure on the tips, with my knees over my toes. It stems from being used to race stock skis that require tip pressure to bend into an arc. I like to be able to play with the radius by bending the skis dramatically.
Yes, race skis (and all skis) do need "tip pressure" to bend into an arc. But this does not suggest that they need only tip pressure, or that we need to selectively pressure the tips more than the tails by levering forward! Perhaps it was more true in the past, when the shapes and flex characteristics of the old skis made it difficult to pressure the whole ski all at once. We could pressure, perhaps, two thirds of the ski at one time, so we had to make a choice between the forward two thirds, the middle two thirds, or the back two thirds. But today's skis (most of them, anyway) are designed such that we can pressure the entire running edge all at the same time--if and only if we find the sweet spot! Maintain pressure on the sweet spot, and you will have all the pressure on the tip that it needs. If you really need to lever forward on your boot tongues to apply sufficient pressure to bend the tips, it is possible that your bindings are mounted too far back.

Take another look at this little animation that I posted earlier:


You can see that this ski, pressure focused at its sweet spot, maintains contact along the entire edge. Assuming that the flex pattern and overall stiffness of the ski (torsionally and longitudinally) are properly engineered, this ski will distribute all the pressure to the tip (and the tail) that it needs!

Best regards,
Bob Barnes

PS--sorry for the belated reply. I am visiting my inlaws in New York, and computer time is at a premium. I am sorry to say that my father in law has recently turned gravely ill. He is part of the EpicSki family, as the designer of the original EpicSki Academy logo. We should be proud of that logo! He created it several years after retiring from a distinguished career as a graphic artist, during which he created many well-known corporate identities including the Coca Cola logo, the Chevron oil company logo, Keebler cookies, Friendly's ice cream, the 1976 Democratic Convention logo, and many others. EpicSki Academy is in good company! Anyway, I thought everyone should know that he is not well, and I'm sure that he, Edna, his wife of 60 years, and all of his friends and family, will appreciate knowing that you are thinking of him! Thank you.
post #43 of 48
Quote:
Originally Posted by therusty
When we have skis that have different tip and tail widths, does this mean that a pure clean carve can not be round? It would seem that such a ski must have different turning radii at the tip and the tail. As such wouldn't there have to be some skidding of some of the ski to get a round turn to happen? My suspicion is that most such skidding, if it were so, would be imperceptible to the untrained eye. Am I on the right track?
Hi Rusty--I agree that most, if not all, "pure carved" turns have some amount of skidding, virtually imperceptible though it may be, for any number of reasons. No ski is "perfectly" designed, and conditions have enough variables that even with "perfect" technique, I suppose it's unlikely that the arc a ski bends into in any real turn is truly perfectly round.

But I do not think that just because the tip and tail are different widths, it is theoretically impossible for the ski to still bend into a perfectly round arc. The shape of the ski's curve, when tipped on edge and pressured, depends on a number of things, including sidecut shape, flex pattern, snow conditions, and amount and focus of the pressure.

Imagine a ski that has an equal-width tip and tail, even flex pattern, and centrally mounted bindings. Tip it, pressure it in the middle, and it should bend into an even arc. Let's say, for the sake of argument, that its shape is such that it bends into a perfectly round arc (segment of a circle). Now, while it's pressured and bent, imagine sawing off a little of its tail. Now it looks more like a typical ski, with the bindings mounted a little aft of center, and the tail narrower than the tip. But it would still describe the same circular arc!

The science--or is it more of an art?--of sidecut and ski shape does not seem to be exact. The shape of the sidecut is not necessarily the same as the shape of the arc of the reverse cambered ski. Remember the "parabolic" design that Elan made so popular? As it was explained to me (admittedly by people more aligned with marketing than engineering), the idea was to create a sidecut shape that, while not round itself, would cause a ski to bend into that perfectly round arc when tipped and pressured. Right or wrong (help me, PhysicsMan!), those skis sure started a revolution, didn't they?

Best regards,
Bob Barnes
post #44 of 48
Yes Bob, I remember those Elans. My red SCX's have been retired to the basement, but I still love them. They are the reason I asked the question. Thanks for the answer - thought provoking as usual.
post #45 of 48
Quote:
Originally Posted by Bob Barnes/Colorado
Imagine a ski that has an equal-width tip and tail, even flex pattern, and centrally mounted bindings. Tip it, pressure it in the middle, and it should bend into an even arc. Let's say, for the sake of argument, that its shape is such that it bends into a perfectly round arc (segment of a circle). Now, while it's pressured and bent, imagine sawing off a little of its tail. Now it looks more like a typical ski, with the bindings mounted a little aft of center, and the tail narrower than the tip. But it would still describe the same circular arc!
Now release the pressurea and press down again. What is the result?
post #46 of 48
Good question, BigE. I thought about it too, and I'm not sure what would happen. There are so many variables involved. But I know two things. By readjusting pressure fore and aft, we can alter the shape of the bend of the ski. And by altering the design of the ski--shape and flex pattern--ski designers can also affect the way the ski bends. So even if cutting the tail off my hypothetical ski would change the shape of its arc, it is still possible to make a ski with differing tip and tail widths bend into a round arc, at least in theory.

Best regards,
Bob Barnes
post #47 of 48
Bob,

You are a good guy to spend time here helping all of us to increase our understanding. You are also a good son-in-law/husband and are tough situation right now. We should all keep your father-in-law in our thoughts and prayers.

I find it interesting that we just had this exact same discussion about ski design/tip pressure/boot levering last week at Loveland with Bob Booker.
post #48 of 48
Thread Starter 
Bob, I am grateful for the time you've spent here with DD and the rest of us.

Know that you and your family are in my prayers--and all of our thoughts, I'm sure.
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