or Connect
New Posts  All Forums:Forum Nav:

Body as an anchor - Page 4

post #91 of 110
That's right, LF.

However, BTS and Jamt have valid points that at times the friction you are relying on does not exist.

Have you ever started a pivot slip in a straight run down the fall line and found it difficult to start the pivot??????????
post #92 of 110

When the pitch is shallow and the snow is deep, yes indeed.

I keep forgetting you guys don't ski on ice.  Ice is nice for pivot slips.

Noisy snow rocks!

post #93 of 110
Quote:
Originally Posted by borntoski683 View Post

Ok, so on a whim I decided to buy Ron Kipp's book on amazon and it came last night.  There is an interesting paragraph on p157 that I am going to quote here.  This should explain all you need to know about how Ron views this subject.  Why he used the description in the recent article of leveraging against an anchored upper half I do not know, but hopefully the confusion of understanding from that is apparent on this thread and will be cleared up by this quote.


Any more questions?

Yep. One question. If Kipp believes this, then why does he start the majority of his turns with upper body rotation (and a quick stem)?
post #94 of 110
Funny!

I grew up in northeast Ohio skiing manmade snow at BMBW, weekend trips to western NY and VT wink.gif

That perfect boiler plate ice is where you'll experience the breakdown of ILS the best. Explore this season smile.gif
post #95 of 110

I'm thinking the exact opposite.  Say more, please.

post #96 of 110
Quote:
Originally Posted by sharpedges View Post


Yep. One question. If Kipp believes this, then why does he start the majority of his turns with upper body rotation (and a quick stem)?

 

Hey just for the record, I am not defending Ron Kipp, his points of view or his skiing.  The OP of this thread asked a direct question about an article he wrote recently and I happen to have his book and came across the paragraphs which I believe clear up any questions about the Razie's original question.  I happen to agree with Ron Kipp's POV on this particular topic as written in his book, though I don't like how he described things in the more recent article.  SharpEdges I believe you probably agree with that point of view also, regardless of whether Ron actually skis the way he preaches or not, and I'm not saying either way on that one.

post #97 of 110
Quote:
Originally Posted by LiquidFeet View Post

I'm thinking the exact opposite.  Say more, please.

To turn one foot against the other as you have described, you need friction/resistance under foot as you have correctly pointed out. When do you have resistance underfoot and when don't you?

This is why BTS is talking about standing on an ice rink and Jamt is pointing to inline skates because they pretty much remove the ground resistance (at some times) and if you try to steer the legs with no resistance you quickly find yourself standing there unable to move unless you employ some other means or resistance source. Another example is flat straight running skis on something really slippery ...say boiler plate while raining which I expect you know something about smile.gif

Bob, Jamt and Skidude covered it really good with images and animations in the physics thread.





Sorry, I'll go back and reread the thread Zenny
post #98 of 110

I'm not sure if this will help or not, but I've had a couple injuries along the way; knees and shoulders.  Each time, I moved using what I though was only the uninjured half of my body to only have pain shoot through the injured half.  I was amazed/surprised several times when I had Rotator Cuff Surgery how often the shoulder comes into play when you are moving, even though you're in a sling!

 

I also remember being in physical therapy and having to stand on one leg (left) and with the opposite side's hand (right), pull a theraband across my body (left to right).  It put tremendous torque on my knee, though my foot never visually moved.  You can't do this without your foot trying to turn in the opposite direction (left).  Each joint between the bottom of my foot and my shoulder were involved.  I think the split was at the hip.

 

If you were floating in a pool and pulled on the strap trying to do the same thing, instead you would just go towards the left.

post #99 of 110
Quote:
Originally Posted by cgeib View Post


To turn one foot against the other as you have described, you need friction/resistance under foot as you have correctly pointed out. When do you have resistance underfoot and when don't you?

This is why BTS is talking about standing on an ice rink and Jamt is pointing to inline skates because they pretty much remove the ground resistance (at some times) and if you try to steer the legs with no resistance you quickly find yourself standing there unable to move unless you employ some other means or resistance source. Another example is flat straight running skis on something really slippery ...say boiler plate while raining which I expect you know something about smile.gif

Bob, Jamt and Skidude covered it really good with images and animations in the physics thread.





Sorry, I'll go back and reread the thread Zenny

Respectfully, I have a couple of questions/comments

 

1. If we are indeed discussing the force of friction, (and not applied force) then we must be discussing skidded turns and not carved turns, yes?

2. If so, your example of standing on the ice is appropriate but your example of inline skates is more of an applied force example than friction.  Hi quality inline skate are designed to remove inertial ground resistance via wheel shape and bearing considerations. However, the compounds used in the wheel are such that they attempt to increase lateral friction thereby reducing skid potential. 

3. If I was standing on the ice in my bare feet (or soft soled shoes) and needed to head for the exit, I would first get control of my CoM and if the exit was to my left, I would rotate my left foot outward toward the left, opening up my left side so that my mass has the opportunity to move in that direction.  I would not be rotating my right foot first against the left. On this highly friction-less surface, my moves would be quiet and subtle. If I had sharp skates on this would obviously be a different scenario although I would still need to clear my left side before providing propulsion from my right. 

post #100 of 110
It's about whether or not we have any fore/aft resistance. In LF's push/pull example there is friction/resistance under foot present against which we can turn the legs. In the ice/inline example this resistance isn't there so there is nothing to push/pull against. This is why in some cases we have to supply that force ourselves in the form of active countering movements (equal and opposite) so that the pelvis acts as the lever arm against which the legs can turn.

Or something like that biggrin.gif

zenny
post #101 of 110
Quote:
Originally Posted by razie View Post
 

I stumbled onto this technical article http://skiracing.com/feature/how-to-improve-your-slalom-skills/ 

 

One of the things there is

 

Quote:

An upper body that provides an anchor for the lower body to lever, hinge and rotate against will allow the skier athletic freedom.

 

First off, I think it's rather stupid to use "anchor" since anchors are small things used to lock big things (ships) in place, while here the body is the big thing and it's defininetly not used to anchor the legs in place but to move them faster... as they state later - so "anchor" is completely the wrong mental image. Also, there is nothing static about skiing, while anchors are all about statics.

 

Using the body's inertia though is a correct and important principle: together with keeping the body on the most efficient line is one of the reasons why retraction is better than extension (where you move the body up and down thus less efficiently) and so on and so forth... also, retraction is a clear example of leveraging the body's inertia, since you use muscles to retract the legs against the body via levers... etc.

 

But, whether you like anchor or not, this principle strikes home in the sense that this is what was on my mind in that other somewhat disastruous thread of my other 12 year old :) where I couldn't quite pinpoint what I was after.

 

There's not many things to work with as a skier: you basically have gravity and inertia thus managing the body's inertia is a lot of what high performance skiing is all about. You manage inertia via the skis (edging, bending, fore/aft) via the body (tipping, flexing/extending, angulating, (counter)rotating etc). There are certainly many schools of thought and levels of understanding on what causes what and what we should focus on.

 

Darn - I already typed a page and didn't get to what I wanted to ask, so I'll just stop at these two questions:

- do you agree with my thinking that the term "anchor" is not applicable - if so, what paints a better mental image?

- do you think that leveraging the body's inertia is something that should be taught directly or never addressed, implicitly managed via the stuff we directly teach, like tipping, flexing/extending, angulating whatever?

 

I may get to ask my other question depending on how this thread evolves.

 

thanks and cheers,

raz


Sorry I can't read the article without signing up for a membership.

 

However, after reading the first few posts (and skipping the rest) I will answer your question.  Reading what the author means by the words instead of what I may mean by the words is a habit I've tried to develop.  The concept (body as anchor) reminds me of something I read in a book on Tae Kwon Do about 40 years ago, written no doubt by a very high ranking proponent of that martial art, and translated into English.  The English translation of the Title was "Korean Karate: the Art of Tae Kwon DO", although I have been corrected by numerous modern-day afficionadoes of Tae Kwon Do that Tae Kwon Do is not Korean Karate (or even Korean Karate Do), there is no such thing as Korean Karate and never was.  

 

I think the words you are searching for to better represent "anchor" as intended in the article are "mobile base of support".

 

Oh wait, look here's a link to the book ...  http://www.amazon.com/Korean-Karate-The-Art-Kwon/dp/0135168155

post #102 of 110
Thread Starter 
Subscrption is free this year.
post #103 of 110
Quote:
Originally Posted by razie View Post

Subscrption is free this year.


It won't let me sign up. 

post #104 of 110
Hi Jesinstr,

Seems like 1 & 2 are false choices to me. Strikes me as the examples mean to illustrate the result (or lack of result) when attempting to apply the forces in a frictionless environment. I'm too long away from the minimal physics I studied and certainly may be using terms inaccurately/inappropriately for the physics gurus and apologize if so. Is resistance a better term instead of friction?

I think Zenny summarized it concerning resistance being needed to oppose the forces attempting to be applied and both examples can work concerning that I believe. I like the frictionless ice rink since there aren't any wheels needing lined up. As you say, the skates can provide resistance, hence why I qualified removal of ground resistance with "at some times." The no resistance stationary ice rink is cool to illustrate the point of what happens to the barstool scenario when you remove the given anchors to the ground, but we don't ski or skate stationary on a flat ice rink with no resistance usually, so I'm not sure how much further the illustrations need taken.

I think the choice between skidding and carving is false also, but that fires up considerable contention as well. Knees exploding, tails of skis levering off the snow, forces in the direction the ski is traveling or not, etc.

Again, the details, points, and counter points were flushed out really well in this thread that was linked earlier:
http://www.epicski.com/t/114527/physics-and-ski-technique

I don't follow what 3 is about for sure, but it seems to me you are assuming friction to work with i.e. where is the equal opposite reaction when you turn the left foot outward and where do you get propulsion from?
post #105 of 110

in some ways all of the arguments about friction and whether or not it can actually be done are a moot point or red herrings.  Trying to ski that way would interfere with so many other good movements as to make it silly.  Do people really want to ski around on evenly weighted skis, focusing on trying to leverage against each other in order to stabilize the upper while twisting both legs?   Why not just balance on the outside ski and counter-act, and make a ski turn the way Witherall and many others have observed good skiing to be?

post #106 of 110
Quote:
Originally Posted by cgeib View Post

Hi Jesinstr,

Seems like 1 & 2 are false choices to me. Strikes me as the examples mean to illustrate the result (or lack of result) when attempting to apply the forces in a frictionless environment. I'm too long away from the minimal physics I studied and certainly may be using terms inaccurately/inappropriately for the physics gurus and apologize if so. Is resistance a better term instead of friction?

I think Zenny summarized it concerning resistance being needed to oppose the forces attempting to be applied and both examples can work concerning that I believe. I like the frictionless ice rink since there aren't any wheels needing lined up. As you say, the skates can provide resistance, hence why I qualified removal of ground resistance with "at some times." The no resistance stationary ice rink is cool to illustrate the point of what happens to the barstool scenario when you remove the given anchors to the ground, but we don't ski or skate stationary on a flat ice rink with no resistance usually, so I'm not sure how much further the illustrations need taken.

I think the choice between skidding and carving is false also, but that fires up considerable contention as well. Knees exploding, tails of skis levering off the snow, forces in the direction the ski is traveling or not, etc.

Again, the details, points, and counter points were flushed out really well in this thread that was linked earlier:
http://www.epicski.com/t/114527/physics-and-ski-technique

I don't follow what 3 is about for sure, but it seems to me you are assuming friction to work with i.e. where is the equal opposite reaction when you turn the left foot outward and where do you get propulsion from?

Believe me, I am in no way a physics guru... just an old retired PE major who can't shake the ski teaching habit.:o

 

I am puzzled by you saying that my #1 and #2 points and the choice between skidding and carving were false choices. Are you implying that the mechanics of a skidded turn are the same as a carved turn?  

 

My understanding of basic physics is that there are 2 categories of forces.  Contact Forces and "At a distance" forces (like gravity, electrical and magnetic etc). Among  the types of contact forces are frictional and applied.  Frictional is about 2 surfaces sliding AGAINST each other ie base of ski and skiing surface.  Applied force is a direct impact force between to surfaces ie edge of the ski IN the skiing surface. Is not the design of the ski such that it will bend when it is in the applied state and pressure is added?  How does one bend the ski in a frictional (skidding) state? Having said that I will acknowledge that most turns are a combination of frictional and applied force but in my mind, each state of force requires a different application of the skills set.  

 

Now, in reference to my #3.  There may be an opportunity for me to learn something here! (for those reading this, you need to read my original post above.)  But here is my take...Since this thread is about the upper body as an anchor, I will say that the equal and opposite (resistance)  force from the turning of my foot coils up into the upper body because Spring Force is yet another type of contact force. This is why I keep my upper body quiet and receptive to inputs from below.  I will also submit that since my foot could be either on the low resistance ice or in the air,  the turning of my foot and hip in this scenario is extremely low force.... and it should be considering what will happen if I should lose my balance.  The propulsion part is a sequential inertial action initiated by the right foot once I have cleared my inside and positioned my mass in the intended direction of travel. 

 

I will stop here because if I need to be slapped upside the head, it needs to be at this point in the discussion.  It may be that we are coming at the same thing but from different perspectives. thanks. John

post #107 of 110
Quote:
Originally Posted by JESINSTR View Post
 

Respectfully, I have a couple of questions/comments

 

1. If we are indeed discussing the force of friction, (and not applied force) then we must be discussing skidded turns and not carved turns, yes?

2. If so, your example of standing on the ice is appropriate but your example of inline skates is more of an applied force example than friction.  Hi quality inline skate are designed to remove inertial ground resistance via wheel shape and bearing considerations. However, the compounds used in the wheel are such that they attempt to increase lateral friction thereby reducing skid potential. 

3. If I was standing on the ice in my bare feet (or soft soled shoes) and needed to head for the exit, I would first get control of my CoM and if the exit was to my left, I would rotate my left foot outward toward the left, opening up my left side so that my mass has the opportunity to move in that direction.  I would not be rotating my right foot first against the left. On this highly friction-less surface, my moves would be quiet and subtle. If I had sharp skates on this would obviously be a different scenario although I would still need to clear my left side before providing propulsion from my right. 

The friction we are talking about is in the fore-aft direction. In the bar stool example the stools are fixed in the fore-aft direction. Standing on the floor or ice or whatever in socks/shows the friction is the same in fore-aft as lateral. On skis and in-lines the fore-aft friction is much lower than laterally, hence to problem with the analogy. Try twisting your skis while standing still in moderately soft snow -quite hard (it is possible but with a completely different mechanism than the "fulcrum")

post #108 of 110
Thread Starter 
Just briefly.

There are reactionary forces as well such as centrifugal.

There are two types of friction: Static and dynamic. Static friction is a ski still carving dynamic is just skidding -

A skidding ski is still bent as snow is not like cement and 2) the skis shape make them bend even on cement as soon as they are tipped with weight on them

Cheers
Edited by razie - 10/27/14 at 7:52am
post #109 of 110
Quote:
Originally Posted by razie View Post

Just briefly.

There are reactionary forces as well such as centrifugal.

There are two types of friction: Static and dynamic. Static friction is a ski still carving dynamic is just skidding -

A skidding ski is still bent as snow is not like cement and 2) the skis shape make them bend even on cement as soon as they are tipped with weight on them

Cheers

Static friction when you carve. I suppose you are going quite slow then ;):ROTF 

post #110 of 110

Jamt. Thanks for the contextual clarification! 

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Ski Instruction & Coaching