Great graphics

[razie]

it would be later on, but she'd lose some of the down the hill momentum if she didn't release - in frame 3 the skis would be pushing her up the hill. If you lose too much down the hill momentum, you'll have to help release and cross the skis somehow... be it extra angulation or hop or something...

 

[LiquidFeet]

it would be later on, but she'd lose some of the down the hill momentum if she didn't release - in frame 3 the skis would be pushing her up the hill. If you lose too much down the hill momentum, you'll have to help release and cross the skis somehow... be it extra angulation or hop or something...

...or an extension.

 

[James]

it would be later on, but she'd lose some of the down the hill momentum if she didn't release - in frame 3 the skis would be pushing her up the hill. If you lose too much down the hill momentum, you'll have to help release and cross the skis somehow... be it extra angulation or hop or something...

Well it’s hypothetical . If the gate was another 5 meters over, she’d hold on to the turn. You now don’t have to do a retraction release. That’s the point. Pretend it’s free skiing.

 

[razie]

Nah... I don't think so... You have to make the next one too and the next one after that and with a diminishing down the hill velocity, you won't even be able to bend the ski, so you start the rain dance and you start skating and pushing yourself - hence the "push down the hill" gallery if they put this offset on the flats, you'd see what I mean

She's just making it in time to bend the ski, the way it is now... Take some speed out of it and she wouldn't make the gate after that one, without pushing and steering

5 or more m maybe she'd have the time to make up some speed back but likely she would have tucked it in that case, so still flexed - I don't see the relevance, if you want me to admit that if the course was much easier she could do whatever, like to extend instead of flexing, it's admitted already - but it would mean a different line altogether for her, not a turning challenge.

For free skiers, should they flex? Yah. We see it all the time at the performance level, all the Reilly's and Tom's and J. Ballou and etc profess it, so why seek to prove that in some scenarios some lesser skiers don't have to? Sure, agreed: you don't have to. Will you get performance skiing if you don't? I highly doubt it... there is a lot of biomechanics behind it, not just the quickness of the transition or this or that line... that's just what these physics heavy discussions get us into...

If you want to make just 5 turns to the bottom, not much technique is needed, just courage

 

[geepers]

And no I still do not think flexion or extension causes transition. Those are both for/aft balance movements that happen during transition but neither are the cause of edge change. Edge change is the ultimate goal of transition. We cannot go the other direction without it.

When I 1st read your point that on fore/aft I was puzzled. Re-watched a Tom Gellie webinar "Retraction Turns or Flex to Release- Getting off the merry-go-round" yesterday and several interesting items came up. (Really have to watch these things a few times to take them in properly...)

The 1st item is that in a progressive release of the body during transition - from torso to feet - the segments will head off tangentially and the result will be an 'effortless' extension into the new turn.

Tom also notes the fore/aft thinking. Says that came from Heluvaskier and now makes sense.

Tom is not a fan of rolling the ankles/knees as the 1st move in transition. It's the other way - hips, knees, ankles. Has an excellent section on practicing/experiencing releasing through dryland drills using an elastic exercise band to simulate centripetal force.

 

[razie]

And no I still do not think flexion or extension causes transition. Those are both for/aft balance movements that happen during transition but neither are the cause of edge change.

Re-watched a Tom Gellie webinar "Retraction Turns or Flex to Release- Getting off the merry-go-round" yesterday

Tom also notes the fore/aft thinking. Says that came from Heluvaskier and now makes sense.

That sounded wrong, so... just to set the record straight - to those, Heluvaskier said, in order, "that's wrong" and WTF (which is quite verbose from him). What he actually said for that video is that most people see the skier look aft when flexing and think that's the purpose of it, which is wrong. Also that you can't train flexing without training fore/aft.

Interesting fact - training fore/aft for flexing is quite different.

 

[Loki1]

Razie, just because a skier flexes the turning leg doesn't mean that the intent or the outcome is a release. Skiers flex and extend all the time for different reasons. I think that may be the big disconnect here. You see any flexion of the turning leg at all and label that turn a flexed release. Just not the case.

 

[LiquidFeet]

Razie, just because a skier flexes the turning leg doesn't mean that the intent or the outcome is a release. Skiers flex and extend all the time for different reasons. I think that may be the big disconnect here. You see any flexion of the turning leg at all and label that turn a flexed release. Just not the case.

@Loki1, when one flexes the "turning leg," it lets go. That's a release, pure and simple. There are other releases.

How do YOU release?

 

[Steve]

When you pedal a bicycle you push down for power. You do not actively flex the other leg, it flexes due to the force of the other leg extending. Can someone determine this by looking?

 

[Loki1]

Liquidfeet

@Loki1, when one flexes the "turning leg," it lets go. That's a release, pure and simple

no it does not. You are saying that flexion equals release. Simply put if I flex my turning leg, my com moves towards my feet, until something else stops it. That is what I’ve been trying to say all along. Flexion, on its own, doesn’t not equal release

 

[LiquidFeet]

Liquidfeet
no it does not. You are saying that flexion equals release. Simply put if I flex my turning leg, my com moves towards my feet, until something else stops it. That is what I’ve been trying to say all along. Flexion, on its own, doesn’t not equal release

@Loki1, it sounds like you're only thinking about gravity. You are not taking into account momentum, which a number of folks in this thread have explained already, each in a different way.

Remember playing crack-the-whip as a kid? Imagine you are the kid on the outside. If your hand lets go of the kid you are holding onto, you go flying away in a straight line before you tumble to the ground. You do not immediately fall straight down towards your feet. Yes, you will probably hit the ground eventually because you'll be moving so fast your feet won't be able to keep up with your CoM.

It's that sensation that causes people to use the words "topple" and "catch" when they describe the sensations of a flexion release. You flex that outside leg, your body crosses the skis fast, and before you even know it your skis, which have flipped to their new edges, are turning downhill and catch you.

 

[razie]

Flexion, on its own, doesn’t not equal release

We can agree on that. There could be some argument on the margin that the unweighted ski stops turning but that's not that relevant for this discussion.

Taking the ski off the edge is the critical part of the release. The way you do that and the other things you do together with it dictate the type of release, imho.

Its not the fact that the leg flexes any time and for any reason - it's when it flexes at a certain time, right after being long at max edge angles, in order to allow flattening the ski in a certain way that makes it a flex to release. Again, you can release in other ways, too, of course.

Some for instance flex in transition - say the leg stays long at the end of the turn and the skier gets the up impulses and after that impulse, the skier flexes - that would not qualify as a flex to release in my mind, at least not a good one... It is a specific phase that some skiers go through when learning the flex to release and with good skiers is hard to tell the differences sometimes. They got good at hiding various versions of a small push-off.

I think also the opposite is also true, likely more frequent, when someone relaxes a bit and allows the leg to flex a bit under power, but then extends so the legs are long again at skis flat - that's not a flex to release; we can maybe call it flexing to end the turn.

So, to call it a good flex to release in my mind, is when the leg relaxes and starts flexing when you decide to release and it continues relaxing and flexing more or less through flat. So basically at max edge angles is longest and at flat it's shortest.

So - you are right, the flex itself is not the release, but it tells which kind of release it was - did you hop off the edge or extend or did you flex - you gotta do one of.

Even when you flex to release, there are several sequences you can use around the weight transfer for instance.

So - did the skier punch off of the BTE or did the skier instead give into it? That's the basic discriminator. No need to explain why or anything - anyone is free to do either.

 

[mister moose]

@Loki1, when one flexes the "turning leg," it lets go. That's a release, pure and simple. There are other releases.

How do YOU release?

A shot of Whistle Pig is my go-to.

@Loki1, it sounds like you're only thinking about gravity. You are not taking into account momentum, which a number of folks in this thread have explained already, each in a different way.

Remember playing crack-the-whip as a kid? Imagine you are the kid on the outside. If your hand lets go of the kid you are holding onto, you go flying away in a straight line before you tumble to the ground. You do not immediately fall straight down towards your feet. Yes, you will probably hit the ground eventually because you'll be moving so fast your feet won't be able to keep up with your CoM.

It's that sensation that causes people to use the words "topple" and "catch" when they describe the sensations of a flexion release. You flex that outside leg, your body crosses the skis fast, and before you even know it your skis, which have flipped to their new edges, are turning downhill and catch you.

Yes, but....

When we flex, isn't what happens while flexing is the pressure on the ski is reduced? Seems to me that might be first in the chain of events you describe. You guys are talking about release like its a hair trigger. Isn't it smoooother... I dunno, ... like.... Whistle Pig?

 

[Loki1]

Liquidfeet,

Remember playing crack-the-whip as a kid? Imagine you are the kid on the outside. If your hand lets go of the kid you are holding onto, you go flying away in a straight line before you tumble to the ground. You do not immediately fall straight down towards your feet. Yes, you will probably hit the ground eventually because you'll be moving so fast your feet won't be able to keep up with your CoM.

The reason skiing is different is becasue in your example the centipital force is coming from above the COM. So when you fly away yes it is pretty much in a stright line. However in skiing the centripital force is coming up from the ski edge to the COM and when that force is released the line the COM takes is more of a diagonal towards the feet. This video will help with what I am saying, start at 2:44. I know it is not exact but it gies you an idea of what I am saying. Listen specifically what he says at the end of the video on where the ball would go without the centripital force.

https://www.khanacademy.org/science/ap-physics-1/ap-centripetal-force-and-gravitation/centripetal-forces-ap/v/identifying-centripetal-force-for-ball-on-string

For some reason it won't let me embed the video.

 

[Loki1]

You guys are talking about release like its a hair trigger. Isn't it smoooother... I dunno, ... like.... Whistle Pig?

Exactly. If it were a trigger and such a quick event then I think we would be more in alignment to what is going on. Because it takes longer and many are also talking about the flexion as not a sudden movement, then the forces don't line up to cause what they are claiming they cause. A lot more important things are going on then just simply flexing or extending during release.

 

[geepers]

That sounded wrong, so... just to set the record straight - to those, Heluvaskier said, in order, "that's wrong" and WTF (which is quite verbose from him). What he actually said for that video is that most people see the skier look aft when flexing and think that's the purpose of it, which is wrong. Also that you can't train flexing without training fore/aft.

Interesting fact - training fore/aft for flexing is quite different.

"most people see the skier look aft when flexing and think that's the purpose of it" Not the way I interpreted what @Loki1 wrote. If that's how you briefed helvuaskier not surprised you'd get an adverse reaction. The issue is managing fore/aft whilst flexing/extending because there's still the need to engage the front of the ski into the fall line. We are moving in 3 dimensions.

 

[razie]

@Loki1 we do not move on a circle it's just a gross approximation used by folks that don't ski with a lot of performance - are doing it wrong.

I touched on this couple times and LF did too : if you release too late, you kill your momentum and then you're skiing differently - flexing won't really work the same way anymore - still important but momentum won't help anymore. Flexing will be a catalyst for a release even when gliding on a green.

In performance skiing and racing you want to maintain the down the hill momentum as much as possible - the power phase is short and in the fall line. The more you grind the ski after the fall line, the bigger the trouble - you get caught in that ball on a string situation, where the ball has no other momentum to deal with, it's stuck and you have to push it up and over or something.

Even in that case though - remember we are turning on an inclined plane, after the fall line, the skis move below the hips which gives the hips this impulse up and over if you don't manage it - exact backwards from that hanging diagram in the video.

No book I have seen so far truly does a correct and complete physics analysis of real skiing... The one at the triple point gets close, others are just gross simplifications, likely from skiers that don't ski well enough - they'll always have blind spots and simplifications and get caught up in red herrings - it would be really interesting to get one of these guys to describe it but you'll likely get just feelings, intentions and reactions, not physics - some may relate technique elements to the intensions, if they were taught or learned properly cause-effect.

 

[mister moose]

However in skiing the centripital force is coming up from the ski edge to the COM and when that force is released the line the COM takes is more of a diagonal towards the feet. This video will help with what I am saying, start at 2:44. I know it is not exact but it gies you an idea of what I am saying. Listen specifically what he says at the end of the video on where the ball would go without the centripital force.

The video is correct, and the last bit is correct, although it's a brief second with no real explanation.

Keep in mind one of the keys in evaluating rotary motion is the plane of rotation. It is this plane that will predict where the ball will go when the string is cut. The other thing going on with both the skier and the video is gravity.

So in the video when the string is cut, the ball travels in the direction it was going at the instant the string is cut, which is tangential to the circle and in the plane of rotation. Vertical speed is zero. The ball will begin to fall.

The video also addresses your point on "the centripetal force is coming up from the ski edge to the COM and when that force is released the line the COM takes is more of a diagonal towards the feet." That is kinda sorta seductively partially true. You need to be more careful with defining what components of what forces are released. The video does a good job of illustrating these components.

In your example yes the legs are the source, but we release the centrifugal component differently than we release the gravity component. Isolate those two components and think again.

 

[mister moose]

↑ And before anyone jumps all over me, I did not mean to write 'centrifugal' in the last paragraph. Satan or spell check must have overcome me. I meant 'centripetal'.

 

[Mike King]

The video is correct, and the last bit is correct, although it's a brief second with no real explanation.

Keep in mind one of the keys in evaluating rotary motion is the plane of rotation. It is this plane that will predict where the ball will go when the string is cut. The other thing going on with both the skier and the video is gravity.

So in the video when the string is cut, the ball travels in the direction it was going at the instant the string is cut, which is tangential to the circle and in the plane of rotation. Vertical speed is zero. The ball will begin to fall.

The video also addresses your point on "the centripetal force is coming up from the ski edge to the COM and when that force is released the line the COM takes is more of a diagonal towards the feet." That is kinda sorta seductively partially true. You need to be more careful with defining what components of what forces are released. The video does a good job of illustrating these components.

In your example yes the legs are the source, but we release the centrifugal component differently than we release the gravity component. Isolate those two components and think again.

So how is the centripetal force released differently than the gravitational force?