Weight on outside ski or inside ski?

[razie]

Where does he fall apart?

good left footer:

bad left footer:

see what happened in between... and how many turns it took him to get back in control...

I agree it's not bad skiing and he compensates well, it's the difference between good athletic skiing and high level technical skiing, in balance and control - which is what he's striving for...

cheers

 

[trouts2]

Given the context of the discussion I was looking for a flaw related to weighting/pressure/balance on an inside ski.

The only issue I saw was at 11 and the next left footer at 9. His inside leg gets jolted 3-5 inches up. You can see the ski riding over something. The front of the ski dips as the tail rides over whatever it was.

The left footer at 9 is a lesser repeat of 11 with what seems to be a smaller hump the ski went over. He’s higher at 10 on the right footer and the last right footer which also is a larger C but he may just be stopping the run at that point.

If the bad left footer photo is not at 11 then I missed it before and again after several more slow motion views tonight.

The bump at 11 was unsettling. His stacking over BoS seemed ok to me but I don’t have such a critical eye and not sure what level you are expecting from him. It seemed like he was at the end of the run and lightening up after 9 sec. If there were still 10 turns to go then it seems like he gave up.....fell apart.

 

[François Pugh]

@razie Speaking of bumps, it looks like the ski got knocked back by a bump, and that put him suddenly forward, resisting that put too much force on the inside tip for him to handle in good form, and that led to the recovery a-frame. Good recovery by the way, even if it took some time. Not sure if he would have had the strength to maintain proper form and power through. You might know.

 

[speedster]

I was thinking Harald Harb while looking at the five video caps of your feet. Can people see why?

Why?

 

[speedster]

Also, I have to say, I don't get this pressure vs weight debate. Since pressure is force per unit area, and force is mass x acceleration. If you lift the inside foot and the "pressure" is on the outside ski, your weight is, um, on the outside ski, since that is the only point of contact between your body and the earth.

Is this pressure vs weight distinction that came about when Harald Harb was trying to invent new terms for regular things as a way to market and differentiate his system?

 

[razie]

Also, I have to say, I don't get this pressure vs weight debate. Since pressure is force per unit area, and force is mass x acceleration. If you lift the inside foot and the "pressure" is on the outside ski, your weight is, um, on the outside ski, since that is the only point of contact between your body and the earth.

Is this pressure vs weight distinction that came about when Harald Harb was trying to invent new terms for regular things as a way to market and differentiate his system?

HH avoids using both weight and pressure... as far as I know. He uses the terms "stance ski" vs "free ski".

If you weigh 180 lbs, that's all the "weight" you get. Pressure on a green run could be between 0 and 180lbs, as you stand on the skis or... not!

However, in a high-performance hip to snow turn, you're pulling towards 3g, which is a short-hand for the centripetal force three times the force of Gravity and results in you creating a pressure 3 times your weight or almost 600 lbs.

p.s. it's a very interesting discussion what gravity is and what a gravitational field is and contrasting that with the centripetal force, which is a very different thing entirely... The gravitational field is measured in acceleration units, for good reason, while the centripetal force is directly related to the mass of the object!​

So, a big difference between standing on a flat ski and feeling "weight" and withstanding 3g pressure in a high-performance carve.

The definition for weight: a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.
"he was at least 175 pounds in weight"

The definition for pressure: continuous physical force exerted on or against an object by something in contact with it.

Yet another thing is lightly engaging the ski at the top of the turn, where you can't talk about weight - you're not "weighting it", not really even really "pressuring it", it's more like just creating balance, since you're just feeling the edge engage - if you dig it in too early, you'll lose the ski and end up skidding. So that's neither weight nor (in my mind) pressure, it's ... just creating balance. This only works if you've flexed in transition, so you control "pressure" and if you got enough energy and impulse from the previous turn, to be able to "float" to the new apex.

If you manage to ski with a lot of offset and high-performance turns, then you'll understand exactly what I mean, as you're lightly engaging the ski as you're moving with it across the slope!

The point being that at a high-performance level, things are a lot more nuanced than just whether or not you're "weighting the ski"

 

[James]

I don't get this pressure vs weight debate.

Don't bother trying. (And likely no one on the wcup gives a rat's about hh. Those turns are pretty, but slower than dirt.)
The main point is that if someone is told to "weight" a ski they're likely to push on it. If you tell them "balance" on it, hopefully they basically just stand on it. Yes, that's put their weight on it.

If you're walking and want to go to the right around a pole. You just lead with the right foot and go that way. All your weight is on the left foot for a moment. Now if you tell someone "put your weight on your left foot, then go to the right" they will move left to go right. The opposite of what you want them to do. The opposite of which we do naturally.

 

[Mike King]

Don't bother trying. (And likely no one on the wcup gives a rat's about hh. Those turns are pretty, but slower than dirt.)
The main point is that if someone is told to "weight" a ski they're likely to push on it. If you tell them "balance" on it, hopefully they basically just stand on it. Yes, that's put their weight on it.

If you're walking and want to go to the right around a pole. You just lead with the right foot and go that way. All your weight is on the left foot for a moment. Now if you tell someone "put your weight on your left foot, then go to the right" they will move left to go right. The opposite of what you want them to do. The opposite of which we do naturally.

I suspect that's why, in part, PSIA talks about pressure, not weight. There are three pressure-related fundamentals:

• Control the relationship between the Center of Mass and the Base of Support to direct pressure along the length of the ski
• Control the pressure from ski to ski to direct pressure toward the outside ski
• Regulate the magnitude of pressure caused by the ski/snow interface.

Two of those are "control" and one is "regulate." All are pressure management.

Mike

 

[speedster]

Don't bother trying. (And likely no one on the wcup gives a rat's about hh. Those turns are pretty, but slower than dirt.)
The main point is that if someone is told to "weight" a ski they're likely to push on it. If you tell them "balance" on it, hopefully they basically just stand on it. Yes, that's put their weight on it.

If you're walking and want to go to the right around a pole. You just lead with the right foot and go that way. All your weight is on the left foot for a moment. Now if you tell someone "put your weight on your left foot, then go to the right" they will move left to go right. The opposite of what you want them to do. The opposite of which we do naturally.

That's a very good explanation, thanks!

 

[speedster]

HH avoids using both weight and pressure... as far as I know. He uses the terms "stance ski" vs "free ski".

Sure he does. Harald's books and writings are full of contradicting information so it's totally understandable why you may be confused. From a quick online search through the first few chapters of his first book, which is still the bible on the PMTS forum and what I believe all beginners are urged to work through religiously:

Chapter 3: “Once the skis reach a final position, place some weight on the free foot to create an evenly pressured stance.”
Chapter 4: “Releasing is the lateral movement started by the feet. By transferring pressure from one side of the boot to the other we effectively tip the skis.”
Chapter 4: “Releasing the stance foot involves taking the pressure off the big toe side and transferring it to the little toe side. Lighten the stance foot as you make this transfer.”
Chapter 5: “Additional speed and steepness require more weight on and edge angle of the stance leg. The game is interesting because with more balance and pressure added to a higher edge angle you gain increased control and ski performance.”
Chapter 5: “By the time the stance ski reacts, a skier has time to adjust and, if necessary, detune the amount of edging and pressure.”
Chapter 5: “Tip contact focuses added turning power on the raised, free ski. This effect can be adjusted by the amount of pressure exerted on the tip.”

 

[razie]

darn fact checking

does the weight vs pressure distinction make sense though as I explained it?

 

[speedster]

darn fact checking

does the weight vs pressure distinction make sense though as I explained it?

A bit. I get exactly what you are describing, but I don't think "balance" or "pressure" are really the best words to explain the process. They have the potential to be as confusing as cross-over and cross-under. There has to be better words, although I can't think of any right now. Or perhaps we don't need specific words, and just the description would suffice -- something like "stand on the outside ski, not push, and feel the edge engage and centripetal forces build."

 

[François Pugh]

Technically, although it only matters to those who know their high school physics:

Weight is the force of gravity. Your weight is the force pulling you towards the centre of the Earth. Since F=ma, and the acceleration due to gravity is g, your weight is your mass, m, times g. Fw=mg.
If you are pulling a "2g" turn, the turn force is twice gravity, i.e. 2 times your weight, or 2mg.
The total force on the ski is the vector sum of 2mg in the direction of the turn and 1mg in the direction towards the centre of the Earth.
If a 150 lb skier made that 2g turn on flat horizontal snow the total force would be pressing with a force of about 335 lbs into the snow at an angle of about 27 degrees to the horizontal. On hero snow, that's no problem, but on ice or boilerplate, you had better beware of boot-out (unless you have wide skis or very skinny boots or both).

Pressure is the force divided by the area over which it is applied.

In the world of ski teaching or coaching, what the words evoke in terms of meaning in the students or athletes head is all that matters.

 

[razie]

@speedster - standing sort of implies weight and pressure...

Since you bring up HH - the way he puts it makes sense to me and it's not ambiguous: extend without pushing. It obviously works with a flexed transition to extend from, but it is very specific and that's exactly what one has to do.

... But that only covers the top of the turn. The transfer sequences are more interesting and that's where the balance notion makes sense to me. At a high-performance level, you're light during the transfer sequences so what did you transfer? Weight? Nope. Pressure? Not really. What's left?

Cheers

 

[Mike King]

Balance.

 

[JESinstr]

@speedster - standing sort of implies weight and pressure...

Since you bring up HH - the way he puts it makes sense to me and it's not ambiguous: extend without pushing. It obviously works with a flexed transition to extend from, but it is very specific and that's exactly what one has to do.

... But that only covers the top of the turn. The transfer sequences are more interesting and that's where the balance notion makes sense to me. At a high-performance level, you're light during the transfer sequences so what did you transfer? Weight? Nope. Pressure? Not really. What's left?

Cheers

As long as we continue to ignore or use the argumentative excuse of "semantics" to (dependent on velocity) not acknowledge that we are either dealing with Gravity (weight) or ski generated Centripetal force for balance, we will keep going round and round in these types of discussions. How we move depends on what force (no matter for how brief a time) is the target of our balance.

 

[razie]

As long as we continue to ignore or use the argumentative excuse of "semantics" to (dependent on velocity) not acknowledge that we are either dealing with Gravity (weight) or ski generated Centripetal force for balance, we will keep going round and round in these types of discussions. How we move depends on what force (no matter for how brief a time) is the target of our balance.

See - that's the problem IMHO: when we say we're dealing with Gravity and Centripetal forces only, we're reduced to either discussing only low-level skiing, where only those two matter or we are reduced to describing only the 10% of the high-performance turn, where those two are in play...

In high-performance skiing, the energy/performance extracted from the turn in the form of the lateral impulse becomes an important part of the discussion. This, however, only applies to serious or at least decent angles, which result in the lateral impulse - otherwise, the impulse is either not there or pointing more up than lateral...

That's the crux of the issue!! It's not a common part of discussions and somewhat tough to comprehend, because not many ski with the angles necessary to feel/understand/justify discussing skiing this way...

Many physics models describing high-performance skiing are generally lacking significant detail, because they're not capturing all the "dynamic" parts of the turn - either the physicists can't ski well enough or the great skiers don't understand physics enough (or don't care enough)...

 

[Mike King]

See - that's the problem IMHO: when we say we're dealing with Gravity and Centripetal forces only, we're reduced to either discussing only low-level skiing, where only those two matter or we are reduced to describing only the 10% of the high-performance turn, where those two are in play...

Gravity and centripetal force ignores the 5th fundamental: "Regulate the magnitude of pressure created by the snow/ski interface."

Mike

 

[JESinstr]

See - that's the problem IMHO: when we say we're dealing with Gravity and Centripetal forces only, we're reduced to either discussing only low-level skiing, where only those two matter or we are reduced to describing only the 10% of the turn where those two are in play...

In high-performance skiing, the energy/performance extracted from the turn in the form of the lateral impulse becomes an important part of the discussion. This, however, only applies to serious or at least decent angles, which result in the lateral impulse - otherwise, the impulse is either not there or pointing more up than lateral...

That's the crux of the issue!! It's not a common part of discussions and somewhat tough to comprehend, because not many ski with the angles necessary to feel/understand/justify discussing skiing this way...

Raz, I was just going to "Like" your response but you make two key points. The first is the physics based impulse point and it is a good one to make for those in the performance level.

And because things happen differently, at different levels, it is no wonder that many coming here for help and knowledge leave totally confused. Worse yet, with things to try out on the slopes that will lead to poor outcomes.

 

[razie]

@JESinstr so the physicist joke cost me a like?


I'm taking steps to correct the problem. We're grooming a soon-to-be-physicist that can ski like this:

He's already started using Ricci Tensors to explain the left turns to me and that cost him a beer.