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markojp

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There's no such thing as knee angulation. It appears this way because of the angle the photo is taken from, and because there is a bit of knee flexion.

The knee doesn't bend laterally.

It can move inward when the femur rotates. This can be good or bad depending on the DIRT and what one does with the pelvis.
 

Doby Man

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Your idea that no rotary occurs in carving. Maybe I mis-read?

Rod is referring to “rotary edging” or active rotary vs. passive rotary which is the leg/hip/spine/shoulder skeletal rotary we use for pure carved, non-skidded turns. Though, if he is saying “no rotary edging”, then he would be by default discussing a non-pivoted turn. Though, edge rotary is typically visually palpable, in anybody’s skiing, "magician" or otherwise, when we are able to see the ski from an angle that shows all direction of its movement. Much depends how a ski will “break” from the pure carve state. I delineate the following options as per my view. Will the shovel break (uphill) first then the tail? We could call that a shovel deflection. If the tail breaks (downhill) before the shovel, we could call that a washout. Regardless, if one end of the ski breaks before the other or, simultaneously in opposite directions (of course), either could be called a pivot. Is it a steered pivot? A stivot. Do they both break together in the direction of momentum? That could be called a skid or a slip. Or do they both break together in the direction of the turn? That could be called a brush. No matter how one prefers to term things, it’s how the ski departs the pure state of carve and how that change in ege hold influences the force vector of our trajectory that makes all the difference, because, whenever we disengage our skis to whatever degree, it is the channel of our momentum that we must then be relying on 100% until we get to the other edge.
 

geepers

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The action/ reaction of femur rotation seems to be worthy of a separate discussion but since we're "waist deep" here.....
There has to be some hip/femur rotational movement in advanced ski turns, otherwise we'd be locked at the waist with no separation or opportunity to square our hips to the fall line/direction of travel.
The point at which we separate the direction of our hips from the direction of the skis, or vice versa, we've introduced rotary movement.
However, I think it's worth separating "good" rotary movements from "bad." I'll call "driving the knee" bad, as you can't bend the knee joint inside - you have to use rotation, and it's almost always used at the wrong time.....right about when we should be rolling our pinkie toe inside!

Ok, bear with me here. This is post 2 for me in a discussion hat has apparently been going on for 20 years. Take this as my understanding at this point and happy to consider other POV.

Let's say we are skiing medium to long radius advanced parallel (carving) turns.
I have no problem understanding what HH means when he says no rotary need be applied; he means you don't have to apply a rotary force through your boots to directly twist your skis, because your skis will twist as a result of snow-ski interaction.

I sometimes wonder if people who don't seem to understand are being deliberately obtuse, and obfuscating. I expect folk to easily understand what HH is saying, and not be confused and think he means that his feet don't rotate, or that his legs are not rotating in their hip sockets. Then again, I am an over-educated engineer with decades of experience in Newtonian physics. Maybe it's the Dunning Kruger effect.

Also, being able to ski without applied rotary does not mean you can't use applied rotary when you need it. (e.g. when skis are in the air, stivots, when you're skiing your rockered skis and need to turn quickly in deep snow in tight trees, etc.). Even HH uses applied rotary when needed; he's just saying you should learn how to ski without it.

Given you are a Newtonian engineer you'd probably like the John Fahey vid. (Personally I'm more of a Maxwellian engineer although in my way of keeping things simple I go for the 4 equations rather than JCM's orginal 20. Sadly this doesn't help my skiing :( although it did help fund it.:)

Anyway I digress. Back to topic...

I've read numerous comments on youtube from H and devotees basically slamming the Nth Amex mainstream ski instructor associations on the way they are supposedly confusing skiers with this rotation of the ski. To the point where I came to the conclusion that any rotation of the ski was considered forbidden under that regime. I did describe toe lifting once to an H fan and it didn't go down well. Personally I never found the CSIA discussions about ski rotation to be confusing and wondered what all the vitriol was about.

I do wonder if The Phantom Move owes more to marketing than anything else. I've had CSIA instructors who teach something vaguely similar, just simpler and without all the hoopla.
 

François Pugh

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I get what you're saying, but am relatively confused. The foot can rotate relative to the leg maybe 10-15 degrees. Therefore the leg can only rotate relative to the foot the same amount. So that's not the relative rotary motion we're talking about. What would we define it more accurately as relative to, pelvis? @François Pugh ?


Read Francois's post otherwise you'll be stuck in an endless loop.
Do you have a link to the Fahey video #3? Sounds like Kate Howe is doing the filming.



View attachment 47185
Ron LeMaster. Mikaela, Aspen WCup Finals 2017

So would this be bad? How about negative knee angulation?

The knee does bend sideways actually, a little. In little kids seemingly quite a bit when crashing.

I find in powder thinking about the knees works better. Maybe because there's not enough immediate feedback from the foot/edge.

Some knee angulation:
View attachment 47191
I define the rotation as rotating the skis to a new pointing direction from that in which they were pointing before you rotated them.
 
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James

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There's no such thing as knee angulation. It appears this way because of the angle the photo is taken from, and because there is a bit of knee flexion.
The knee doesn't bend laterally.
Knee angulation isn't defined as bending sideways of the knee. It's a result of flexion and femur rotation. Assuming an unlocked ankle.

An angular definition in picture c.

IMG_5314.PNG

https://brage.bibsys.no/xmlui/handle/11250/171325
 

Rod9301

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Knee angulation isn't defined as bending sideways of the knee. It's a result of flexion and femur rotation. Assuming an unlocked ankle.

An angular definition in picture c.

View attachment 47237
https://brage.bibsys.no/xmlui/handle/11250/171325
That's fair, I think though that the name is misleading.

Anyway, weak position for the knee, and totally unnecessary.

If the purpose is to get higher edge angle, best way is to keep tipping and shortening the inside leg.

By concentrating on the outside ski, it's hard to get high edge angles.
 

Doby Man

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I define the rotation as rotating the skis to a new pointing direction from that in which they were pointing before you rotated them.

Yes, but wouldn't that definition describe either passive rotary of the ski in an edge locked turn or active rotary of the edges in a pivoted or skidded turn? The term "rotary" in of itself only describes so much. The term really needs to be supported by more equipment and/or biomechanical context before it means anything more than how Webster describes the term. There really is no authoritative definition in ski terms for the word "rotary" by itself. Again, you could be talking about active/passive, the ski and not the edge, the edge against the snow, the edge and the foot, the foot and the knee, the ankle and hip socket , the hip socket and the waist - shoulders - neck - etc.

Ultimately, what the ski is doing is far more indicative of rotary than what the body is doing as it is so indicative of everything else. Nothing is truly clear until final ski output is described. In that light, rotary is for either active and edge associated for skidding, smearing, pivoting, stivoting, scarving, redirection and friction for speed control - or - for for passive, skeletal associated movements for pressuring the outside ski and running that pressure migrating from tip to tail.

When we look at a graph of a turning skier from the top down, imagine three points: the BoS, the CoM and the pivot point of the CoM over the Bos. You would notice that, when the skier turns (carving), the CoM rotates on a parameter outside of the central axis of the BoS in the direction where we want pressure over the ski in any particular point in the turn. As the CoM rotates around the axis of the BoS our weight/pressure is applied to the ski whereever the CoM goes, and "swinging" over the four basic quadrants of the skis: Left shovel, left tail, right shovel, right tail. It migrates to the left shovel then left tail, return to center with 50/50 pressure in transition and "squared" up neutral with all rotary, angulation and inclination , then right shovel then right tail and return to center and so on ...

However, when we rotate our feet and skis against the snow under our body for any type of the rotary edging listed above, the CoM can rotate directly over the BoS, or the BoS directly under the CoM, with the CoM, the BoS and the pivot point between the two are all lined up and are without the parameter "swing" to control pressure over the four quadrants of the skis. The more the ski is skidding vs carving the more open chained our system is and the more difficult it will be to make powerful movements. Conversely, the more both skis are edgelocked into the turn, the more closed chained our system is. The more the system is closed chained, the more we can make the CoM "swing' the parameter over the BoS with much more powerful rotary and therefore have more control over our movements. In other words, our movements are much more pronounced, effective and efficient over a closed chained double edge locked pair of skis and is why I find it much more intriguing.

A visual below to the left of the four quadrants of the transverse plane that the CoM will travel with the use of skeletal rotation and tipping over the central axis of the feet or BoS. Imagine the vector between the CoM and BoS creating an imaginary "joystick" control over pressuring the ski. That is the CoM BoS relationship management that we talk about. Note that the CoM need not travel far over this transverse plane when using rotary edging and is, as well, not as able to do so as much in an open chained unlocked or less locked ski. Note that the travel of the CoM over the transverse plane looks more like a half circle residing in the frontal transverse plane,

20a.jpg
 

markojp

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That's fair, I think though that the name is misleading.

Anyway, weak position for the knee, and totally unnecessary.

If the purpose is to get higher edge angle, best way is to keep tipping and shortening the inside leg.

By concentrating on the outside ski, it's hard to get high edge angles.

Why is it totally unncessary? I find it very useful tactically and don't hesitate to mention it to people I'm working with (judiciously) if there's an appropriate application, which there is. The French demo team did a bunch of it to get the new outside ski on edge before the fall line. Racers use it to adjust their line, etc... it's a micro, not a macro, but it does have a place in the toolbox IMHO.
 

Rod9301

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Why is it totally unncessary? I find it very useful tactically and don't hesitate to mention it to people I'm working with (judiciously) if there's an appropriate application, which there is. The French demo team did a bunch of it to get the new outside ski on edge before the fall line. Racers use it to adjust their line, etc... it's a micro, not a macro, but it does have a place in the toolbox IMHO.
If you' re inclined you will be on edge before the fall line.

Again, it's because it takes focus away from the inside ski.
 

Average Joe

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Deep snow and/or crud conditions require different techniques. Rotary isn't what we aspire to use on groomers but you'd be hard pressed to avoid it's use in pow.
(For those of us old enough to actually turn in powder:)
 

mdf

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Deep snow and/or crud conditions require different techniques. Rotary isn't what we aspire to use on groomers but you'd be hard pressed to avoid it's use in pow.
(For those of us old enough to actually turn in powder:)
I just learned over Mother's Day how useful a small amount of rotary is in crud. To get more speed control on a steep slope. I would ordinarily do a drifted turn ("brushed carve") by modulating the edge angle around the critical edge angle. But on steep, heavy mashed potatoes, a drifted turn is a frightening (and unpredictable) proposition. And an edge locked turn is no bargain either. The solution is to get truly neutral at transition (fore-back as well as side-to-side). Then you can easily rotate your skis a little ways out of the fall line, even in heavy wet deep snow, before starting a normal tipping initiation. Just a little lets you get across the hill without digging your edges in so deep that it becomes hard to get out of the turn.

This was the first time I skied these conditions without that nagging "I'm going to wreck myself" fear.

That said, I think you need to have a solid tipping initiation before you can try to add this.
 

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This is a pretty interesting read on medial and lateral knee rotations. In my mind it seems as if they MUST be tied to pronation and supination of the foot and then of course to internal and external hip rotation, for balancing and stacking purposes. Note that such wouldn’t be possible without either STJ rotation OR hip rotation. It’s all tied together...that’s the value of looking at biomechanics, imo.

http://boneandspine.com/knee-range-of-motion/

zenny
 

James

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This is a pretty interesting read on medial and lateral knee rotations
What's the deal with your pronating and supinating? Mr. Singh did not discuss. (Not sure I'd describe medical non writers as interesting. Mind numbing perhaps) Now, back to listening to a program on English murderers to go to sleep.

Just a little departure for my ah hah moment: I think this must have been what Clendenin meant when he said keep your weight on the uphill ski to prevent a wedge in his bump video which totally confused me until I watched this video. Thanks
IMG_5317.PNG


That's fair, I think though that the name is misleading.

Anyway, weak position for the knee, and totally unnecessary.

If the purpose is to get higher edge angle, best way is to keep tipping and shortening the inside leg.

By concentrating on the outside ski, it's hard to get high edge angles.

You didn't like the definition before, you're really not going to like it now. The above image is knee angulation. It's just a negative value. (Left leg)

Curious, if the goal is higher edge angle on the outside ski, how does tipping the inside get you there? That outside edge angle is basically set by inclination. Inclination is set by the flex of the inside leg - how much the com can tip in. A given speed/radius can only support so much inclination/edge angle. Need more and you angulate to get it.
I don't see how tipping the inside foot gets your goal of increased outside edge angle. Unless one can't shorten the inside leg without tipping the foot.
 
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Zentune

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What's the deal with your pronating and supinating? Mr. Singh did not discuss. (Not sure I'd describe medical non writers as interesting. Mind numbing perhaps) Now, back to listening to a program on English murderers to go to sleep.


View attachment 47259



You didn't like the definition before, you're really not going to like it now. The above image is knee angulation. It's just a negative value. (Left leg)

Curious, if the goal is higher edge angle on the outside ski, how does tipping the inside get you there? That outside edge angle is basically set by inclination. Inclination is set by the flex of the inside leg - how much the com can tip in. A given speed/radius can only support so much inclination/edge angle. Need more and you angulate to get it.
I don't see how tipping the inside foot gets your goal of increased outside edge angle. Unless one can't shorten the inside leg without tipping the foot.

Oh, I don’t know James. How about that these movements of the foot/ankle complex are something everyone does (not everyone does well, but I digress) and that they help us sense the ground and balance on it and propel our masses forward? Without considering their musculoskeletal importance, discussing things like ‘knee angulation’, hip rotation, flexion/extension, lateral spinal flexion, etc as they relate to skiing is missing part of the overall picture? Understanding them better could help answer your question to Rod9301 seeing as how inversion/eversion (foot tipping) are intimately tied to both? Glad you enjoyed the read! :rolleyes:

zenny
 
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James

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Oh, I don’t know James. How about that these movements of the foot/ankle complex are something everyone does (not everyone does well, but I digress) and that they help us sense the ground and balance on it and propel our masses forward? Without considering their musculoskeletal importance, discussing things like ‘knee angulation’, hip rotation, flexion/extension, lateral spinal flexion, etc as they relate to skiing is missing part of the overall picture? Understanding them better could help answer your question to Rod9301 seeing as how inversion/eversion (foot tipping) are intimately tied to both? Glad you enjoyed the read! :rolleyes:
zenny
Hey, at least I read it. My issue with most medical anatomy things is they're rarely connected to activities. Anatomy videos are always separate systems. Skeletal or muscular. I get it's complicated, but it's like a lecture in quantum dynamics.

The complicated part is also things may not work the way it's "supposed" to work. So when you type an all caps phrase of warning I wonder what your talking about, not Mr. Singh.

Should have phrased "your deal" better. For example, @Jamt's theory is that tipping fom the foot versus not is what can separate hip dumping vs not.
So, that's the question.

How about boot fit? What happens if your boot doesn't allow space for the foot to pronate and supinate. Many bootfitters use pronate as a dirty word to sell you a footbed.
Is foaming a liner a good idea?

How does inside foot tipping get one more edge angle on the outside ski? (Asked of Rod)

Finally, some people here have serious ankle disfunction. Can they knee angulate? What happens?
 

markojp

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If you' re inclined you will be on edge before the fall line.
Again, it's because it takes focus away from the inside ski.

It's all about application and degrees therein.

Speaking only for myself, I can think about both skis.... simultaneous, but independent.
 

Rod9301

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Hey, at least I read it. My issue with most medical anatomy things is they're rarely connected to activities. Anatomy videos are always separate systems. Skeletal or muscular. I get it's complicated, but it's like a lecture in quantum dynamics.

The complicated part is also things may not work the way it's "supposed" to work. So when you type an all caps phrase of warning I wonder what your talking about, not Mr. Singh.

Should have phrased "your deal" better. For example, @Jamt's theory is that tipping fom the foot versus not is what can separate hip dumping vs not.
So, that's the question.

How about boot fit? What happens if your boot doesn't allow space for the foot to pronate and supinate. Many bootfitters use pronate as a dirty word to sell you a footbed.
Is foaming a liner a good idea?

How does inside foot tipping get one more edge angle on the outside ski? (Asked of Rod)

Finally, some people here have serious ankle disfunction. Can they knee angulate? What happens?
I don't know the physics of why tipping the inside foot gets you more edge angle, but it somehow pulls the hips to the inside and affects the edge angle of the other, outside ski.

Possibly because it removes the inside leg as base of support.

You have to shorten in at the same time.
 

Zentune

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Hey, at least I read it. My issue with most medical anatomy things is they're rarely connected to activities. Anatomy videos are always separate systems. Skeletal or muscular. I get it's complicated, but it's like a lecture in quantum dynamics.

The complicated part is also things may not work the way it's "supposed" to work. So when you type an all caps phrase of warning I wonder what your talking about, not Mr. Singh.

Should have phrased "your deal" better. For example, @Jamt's theory is that tipping fom the foot versus not is what can separate hip dumping vs not.
So, that's the question.

How about boot fit? What happens if your boot doesn't allow space for the foot to pronate and supinate. Many bootfitters use pronate as a dirty word to sell you a footbed.
Is foaming a liner a good idea?

How does inside foot tipping get one more edge angle on the outside ski? (Asked of Rod)

Finally, some people here have serious ankle disfunction. Can they knee angulate? What happens?

That’s a host of loaded questions. Not tipping LTE as you suggest can cause an over emPHAsis on the outside foot/leg right at the same moment that foot is ideally (and briefly) pronating. But since your inside leg is ‘in the way’ your outside will soon run into it, necessitating further ‘knee drive’ (to achieve more edge) which includes internal leg rotation and which in turn only further promotes continued pronation, because internal rotation of the leg is a component of a pronating foot. . And since pronation is a key component of the body’s *suspension* it is not a very strong position from which to resist a large force and so you will possibly end up “collapsed” inside, maybe with a hip dump to boot as Jamt would note (dumping in the hip can help overcome the ‘blocking of the inside leg’).

I would say that for people with ankle disfunction that some of it could be restored with strengthening/therapy perhaps, but I am not a doctor. They would quite possibly have difficulty with lower leg rotation around the STJ depending upon the disfunction though. Knee rotation would be in part be dependent upon internal and external rotation of the talus so those people may have to drive all from the hip......regardless, pronation is not a “bad” word. Rather it is quite necessary. It’s OVER-pronation that is problematic and many people over-pronate.

Of course some people’s boots do have not enough room, they’re too tight, they have bad ankles, etc it’s true. In THOSE cases driving from the hip to the knee may be the only option?

Also it’s true there often isn’t much room for inversion/eversion in the boot so the movement translates to the tibia instead in the form of rotation, for those with healthy lower limbs...

zenny
 

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