Tipping the foot inside the boot first - why?

[LiquidFeet]

........
2. To start to transition, needs to unbalance himself against centripetal force so centrifugal force wins and pulls him across the skis and into the new turn.
3. Says there's a few different ways to do this - he says he does it by pressing on the short inside leg to raise the CoM to start the transition.
4. He then softens and shortens the old outside leg to stop the CoM having to rise into a high position as that will take longer for it to cross the skis and get on to the new edges. (At this point he's still on the old outside BTE.)....

Harold Harb says this? Amazing. If so, he has made a major adjustment to PMTS technique. I wonder when he made this shift.

He has always been absolutely set against new outside leg extension at initiation. It's the forbidden movement. PSIA, on the other hand, for years promoted "extend to release." When I took my LII skiing exam success depended on the skier lengthening the new outside ski to lift the CoM up and over the skis. This has been the major recognizable difference between PMTS and all other teaching systems, and HH has made a very big deal of it when criticizing them. PSIA has made the shift as well, but PSIA teaching has not been as insistent on a single way to initiate turns as HH has, at least not while I've been instructing.

HH definitely started talking about lifting the new inside ski with the tip higher than the tail after watching WC racers do it. I remember when he first posted about that. That too was a major shift in PMTS. Lifting the tail of the new inside ski had been a major piece of PMTS orthodoxy.

 

[LiquidFeet]

Oh wait. The video we are discussing is not Harald Harb. It's Paul Lorenz. So HH has not shifted his focus on initial initiation movement from shortening the new inside leg, NIS, to lengthening the new outside leg, NOS.

 

[Yo Momma]

Harold Harb says this? Amazing. If so, he has made a major adjustment to PMTS technique.

lifting the new inside ski with the tip higher than the tail .

Thank you for posting this. For me, this was the "lightbulb" moment that woke me up. When helping others to progress, this is my focus. For me, that new inside ski is your downhill ski, as it transitions to being your uphill ski. Code between Wifey and I for this focus is " ski your uphill ski " ... that is our verbal reminder to refocus on this movement. Different instructors are going to manage the discussion of that movement in different ways.

I taught language for many years under Prof. John Rassias while at Dartmouth. A command of language is critical especially when taking into account that we ALL have different interpretations of "Language", esp when it comes to defining and understanding movement and how to execute.

Good instructors know how to use language and vary their translations of movement into the "Words" that each individual student may understand. The really good instructors are adept at accomplishing this on the fly, from moment to moment within the context of the student processing all the different inputs, from weather, to discomfort, thirst, hunger, snow conditions, fitness levels, social issues and everything else our brains are processing at any given moment. Claiming the student's attention and having them re-focus on the movement takes a carefully choreographed verbal flow.

Kudos to HH for maintaining his philosophy

 

[JESinstr]

Hmmm... seems that may be needed for the 1st turn of the run. In subsequent turns surely we can make use of the centripetal/centrifugal force from the previous turn to move our body from one side of the skis to the other?

The tipping of the feet happens as the body crosses the feet and in, say, a dbl leg retraction turn, the skis are already unweighted.




This is the pretty much the model I'm trying to replicate but think much less performance. (Low flying Cessnas can pass between my hips and the snow.)

I think that he tips the old outside foot and shortens it, which
Removes the support, which topples him
And puts all weight on the new outside ski and because of his inclination, of on edge.

Thank you for posting this. For me, this was the "lightbulb" moment that woke me up. When helping others to progress, this is my focus. For me, that new inside ski is your downhill ski, as it transitions to being your uphill ski. Code between Wifey and I for this focus is " ski your uphill ski " ... that is our verbal reminder to refocus on this movement. Different instructors are going to manage the discussion of that movement in different ways.

I taught language for many years under Prof. John Rassias while at Dartmouth. A command of language is critical especially when taking into account that we ALL have different interpretations of "Language", esp when it comes to defining and understanding movement and how to execute.

Good instructors know how to use language and vary their translations of movement into the "Words" that each individual student may understand. The really good instructors are adept at accomplishing this on the fly, from moment to moment within the context of the student processing all the different inputs, from weather, to discomfort, thirst, hunger, snow conditions, fitness levels, social issues and everything else our brains are processing at any given moment. Claiming the student's attention and having them re-focus on the movement takes a carefully choreographed verbal flow.

Kudos to HH for maintaining his philosophy

Geepers may have unwittingly exposed, and Yo Momma makes an excellent point, on why many of our discussions go on and on with no end in sight. The failure of many to understand that skiing takes place in two totally opposite "kinetic universes". The "kinetic universe" of Gravity pulls on us and the "kinetic universe" of Centripetal Force pushes. This is why well-intentioned opinions on technique and teaching progressions are often flawed.

From a strictly dynamic balance perspective, how we kinetically initiate a ski turn is heavily dependent on the force of record at the time. In high velocity, linked turns where the developed Centripetal Force is by far and away the most dominant, the gravitational terms Weight and Topple are not in play. When teaching a beginner or instituting a drill at low velocities, the reverse is true. This is why some drills fail to solve a problem.

Just as in golf, this is a lot about the saying "What you feel is not real".

 

[mdf]

In high velocity, linked turns where the developed Centripetal Force is by far and away the most dominant, the gravitational terms Weight and Topple are not in play.

When I say topple, I am definitely including centrifugal force.

 

[mister moose]

The failure of many to understand that skiing takes place in two totally opposite "kinetic universes". The "kinetic universe" of Gravity pulls on us and the "kinetic universe" of Centripetal Force pushes. This is why well-intentioned opinions on technique and teaching progressions are often flawed.

From a strictly dynamic balance perspective, how we kinetically initiate a ski turn is heavily dependent on the force of record at the time. In high velocity, linked turns where the developed Centripetal Force is by far and away the most dominant, the gravitational terms Weight and Topple are not in play. When teaching a beginner or instituting a drill at low velocities, the reverse is true. This is why some drills fail to solve a problem.

Isn't it true that the earth pushes up against you? And isn't it true that in both of your cases the forces need to be aligned? I'm not so sure that this quite the case of two universes. There is a steady smooth continuum transitioning from static to dynamic.

 

[mdf]

Gravity pulls, the vertical component of ground reaction force pushes back.
Centrifugal force pulls, the centripetal component of ground reaction force pushes back.
Any non-compensated portion causes acceleration.

 

[migdriver]

When I say topple, I am definitely including centrifugal force.

 

[JESinstr]

When I say topple, I am definitely including centrifugal force.

I believe I said Centripetal Force. To Topple is to fall so how can you fall against a force that is pushing out/up at you? If you bring a group of skiers into a circle and tell them to topple, where do you think they will end up? When Gellie talks about toppling he is really trying to get you over your skis and moving in the direction of the new turn in a high-performance scenario and IMO he has chosen a poor word for an excellent movement.

Isn't it true that the earth pushes up against you? And isn't it true that in both of your cases the forces need to be aligned? I'm not so sure that this quite the case of two universes. There is a steady smooth continuum transitioning from static to dynamic.

You will need to discuss that first sentence with Mr. Newton
Yes, forces need to be aligned but have you considered the origins of the forces at play?
Would you consider Kinetic Ecosystems? My point is the kinetic chain to initiate a turn at low velocity is different from high performance turns.
Not talking about static vs dynamic here. Dynamic Balance in skiing means balance "while on the move" whether it's 3MPH or 40MPH.

Gravity pulls, the vertical component of ground reaction force pushes back.
Centrifugal force pulls, the centripetal component of ground reaction force pushes back.
Any non-compensated portion causes acceleration.

??? Think you got it backwards
It is the ski/skier generated Centripetal force that creates the phenomenon we know as Centrifugal force. There are arguments regarding what the definition of Centrifugal force really is. In the context of skiing, I look at Centrifugal force as being the force that is trying return the skier's mass to a straight-line direction of travel. All one has to do is release their edges to experience that. The energy (velocity) source for both Centripetal and it's resulting Centrifugal component is the pull of gravity in combination with the slope of the hill.

This goes to my assertion that what many skiers feel is not real. Those who learn to feel the generated push of Centripetal vs the pull of reactive Centrifugal know what I mean.

 

[mdf]

Think you got it backwards

nope

 

[geepers]

Harold Harb says this?

I'm glad your next post corrected that - potential for much confusion!

It is of course the words of Paul Lorenz describing his own skiing.

 

[François Pugh]

As much as I am tempted to stay out of this argument, it is too painful to watch.
The easiest way to think about it is that there are body forces, like gravity, magnetism, and what is typically called centrifugal (centre-fleeing) forces. Properly speaking, centrifugal force is what we use to make Newtonian physics (F=ma) apply in an accelerating frame of reference i.e. one that moves with the accelerating skier - but not getting into that now. There are also contact forces, acting at points of contact.

Think of the body force as a combination (vector addition) of gravity and centrifugal force, with the centrifugal force changing. The total body force is changing direction as the harder you turn, the more the centrifugal part pulls (points) to the outside of the turn, and the less you turn the more the body force pulls to the earth (no turn = no centrifugal part).

The contact forces act on your ski edges.

You "topple" about your ski edges because the net force adds up to pull you around them.

Ideal ski carving, you have three paths right ski, left ski and body mass. Left ski and right ski are controlled by edge tipping at the right time. Body mass is moved by the net combination of forces including contact forces and body force. You need to move the mass where it needs to be to control the ski to put them in the right position at the right time and pressure them correctly to move your mass where you want to be.

Clear as mud.

 

[geepers]

Yep JESinstr. Lotta good points in that post.

two totally opposite "kinetic universes". The "kinetic universe" of Gravity pulls on us and the "kinetic universe" of Centripetal Force pushes.

One universe. Different forces (gravity, centripetal, friction) acting on the same mass. No need to go multi-versing.

Would you consider Kinetic Ecosystems?

the gravitational terms Weight and Topple are not in play.

Gravity is always in play, thankfully! No skiing without it. Which is why we find ourselves sitting on our bum occasionally.


Seems the word toppling is emotive. For me it well defines what happens when we change the orientation of the CoM to the centripetal force vector or lessen/remove that force. The CoM changes path and moves into the new turn (hopefully). But, hey, call it whatever.

Gellie neither invented nor is the only person/organisation using the term.

 

[Tony S]

(centre-fleeing)

Nice one.

 

[JESinstr]

Gravity pulls, the vertical component of ground reaction force pushes back.
Centrifugal force pulls, the centripetal component of ground reaction force pushes back.
Any non-compensated portion causes acceleration.

??? Think you got it backwards
It is the ski/skier generated Centripetal force that creates the phenomenon we know as Centrifugal force. There are arguments regarding what the definition of Centrifugal force really is. In the context of skiing, I look at Centrifugal force as being the force that is trying return the skier's mass to a straight-line direction of travel. All one has to do is release their edges to experience that. The energy (velocity) source for both Centripetal and it's resulting Centrifugal component is the pull of gravity in combination with the slope of the hill.

This goes to my assertion that what many skiers feel is not real. Those who learn to feel the generated push of Centripetal vs the pull of reactive Centrifugal know what I mean.

nope

You're a passenger in a car traveling 50 MPH down the Road. This car has a bench seat that we added a bit of grease to.
Suddenly, the driver swerves to the left and you collide with the right-hand door.

Did you move into the door or did the door move into you?

 

[JESinstr]

Nice one.

So what centre are we fleeing?

 

[geepers]

Nice one.

Still trying to get over "sentry petal".

Did you move into the door or did the door move into you?

From a frame of reference external to the car the door moved into you as you were an object in motion and will remain on current velocity vector until acted on by another force. When you meet the door it applies centripetal force to take you around the corner with the car. (Or opens and spills you out on the road.) All the while the bench seat applies an upward force to counter the gravitational force and that upwards force stops you falling through the bottom of the car.

From a frame of reference attached to the car a centrifugal force propelled you across the seat until you reached the door.

 

[JESinstr]

Yep JESinstr. Lotta good points in that post.

One universe. Different forces (gravity, centripetal, friction) acting on the same mass. No need to go multi-versing.

Understand and don't disagree. Do you agree that the kinetics of turn initiation (especially in terms of balance) are dependent on velocity? Meaning that the initial force we use to bend the ski could be Gravity or it could be Centripetal

Gravity is always in play, thankfully! No skiing without it. Which is why we find ourselves sitting on our bum occasionally.

Agree on that but we need to understand that we use Gravity for 2 purposes. 1. Velocity and 2. "Stand up" Balance.
Depending on the amount generated Centripetal force, it is that force we use to keep our bum off the snow.... occasionally

Seems the word toppling is emotive. For me it well defines what happens when we change the orientation of the CoM to the centripetal force vector or lessen/remove that force. The CoM changes path and moves into the new turn (hopefully). But, hey, call it whatever.

Gellie neither invented nor is the only person/organisation using the term.

no disagreement that we are talking change in orientation.

 

[JESinstr]

From a frame of reference external to the car the door moved into you as you were an object in motion and will remain on current velocity vector until acted on by another force. When you meet the door it applies centripetal force to take you around the corner with the car. (Or opens and spills you out on the road.) All the while the bench seat applies an upward force to counter the gravitational force and that upwards force stops you falling through the bottom of the car.

From a frame of reference attached to the car a centrifugal force propelled you across the seat until you reached the door.

Correctamundo!
And so, what we feel (skier Frame of Reference) is not real. What is real is coming from the ski snow interaction Frame of Reference. For a skier to react to his/her Frame of Reference means their mechanics are reacting to and fighting the pull of gravity vs focusing on using the Centripetal generating function of the ski to convert the straight line pull of gravity into circular (Centripetal) travel.

 

[geepers]

Understand and don't disagree. Do you agree that the kinetics of turn initiation (especially in terms of balance) are dependent on velocity? Meaning that the initial force we use to bend the ski could be Gravity or it could be Centripetal

Agree on that but we need to understand that we use Gravity for 2 purposes. 1. Velocity and 2. "Stand up" Balance.
Depending on the amount generated Centripetal force, it is that force we use to keep our bum off the snow.... occasionally

no disagreement that we are talking change in orientation.

Think we are basically on the same page - we're down to discussing details of syntax.

There is no difference between gravitational "force" and centripetal force. (Except the magnitude.) Standing on Earth resisting the 1g of GRF is exactly the same as standing in a rocketship accelerating at 1g - without some external reference it's impossible to tell the difference. If the rocketship was accelerating at 1g in one direction and at the same time accelerating 0.5g (or 2g or whatever g) in a direction at right angles to that then we'd have to balance against both those accelerations to avoid falling over. And it would be exactly as if we were standing on skis on Earth and going around a turn at the matching number of g's.

Correctamundo!
And so, what we feel (skier Frame of Reference) is not real. What is real is coming from the ski snow interaction Frame of Reference. For a skier to react to his/her Frame of Reference means their mechanics are reacting to and fighting the pull of gravity vs focusing on using the Centripetal generating function of the ski to convert the straight line pull of gravity into circular (Centripetal) travel.

I'd express it a little differently than real / not real. Inertia is real enough.

As we improve, especially at circular travel, we have to change from an experience dominated by gravitational force to one in which centripetal force is present and may even be the larger of the two. But we need to work with both.