or Connect
New Posts  All Forums:Forum Nav:

# Lifting the inside ski... - Page 5

Quote:

Yes, that is 100% true, but that doesn't discount that there are only two turns.
The physics of a ski on 2d snow is really simple for the most part. There are plenty of websites like this that explain it:
http://www.real-world-physics-problems.com/physics-of-skiing.html

A carved turn only has two forces applied to it, a tipping force to the side, and a forward force to maintain tip pressure.

Any other turn requires a third force, a rotating force. Newtons first law demands it. Once the ski is broken out of a carve it needs a rotary force to change directions, otherwise you would go in a straight linee.

You can call either of these turns anything you want, but due to the force vectors there is only two of them possible.

I lifted my skis, stemmed, and did all sorts of aweful skiing tonight. No one of it in the name of good skiing. I don't think I have skied in such nasty conditions.

Where is that rotary force coming from?

It could come from femur or it could come from the ground reaction forces (GRF). Generally the more of the forces that come from GRF the better the skiing.

Do you know that it is not possible to provide a continuous torque from the femur to affect the ski? By Newtons third law if you twist the skis you twist the upper body the other way.

Most people who think they are steering by twisting the femurs are not, at least not in the way they think. You can get some temporary change of the force but that is by twisting the upper body the other way. I'd rather call that countering.

You could argue that a carved turn is when the platform angle is larger than 90 degrees. I'd rather call this an edge locked carve. However, not even this definition would be strict because in reality you have torsion along the ski so that tip and tail has a smaller platform angle. There is no finite point where the whole ski becomes carved. What is carving then?

Further in reality the platform angle changes rapidly all the time due to terrain.

I used to have the opinion that a carved turn needed to be edge locked, but due to the above and after reading BTSs motivations in another thread (a long time ago) I changed my mind. I agree with the definition that FOM and BTS have in this thread. It is much more useful.

Quote:

Yes, that is 100% true, but that doesn't discount that there are only two turns.
The physics of a ski on 2d snow is really simple for the most part. There are plenty of websites like this that explain it:
http://www.real-world-physics-problems.com/physics-of-skiing.html

A carved turn only has two forces applied to it, a tipping force to the side, and a forward force to maintain tip pressure.

Any other turn requires a third force, a rotating force. Newtons first law demands it. Once the ski is broken out of a carve it needs a rotary force to change directions, otherwise you would go in a straight linee.

You can call either of these turns anything you want, but due to the force vectors there is only two of them possible.

I lifted my skis, stemmed, and did all sorts of aweful skiing tonight. No one of it in the name of good skiing. I don't think I have skied in such nasty conditions.

I agree with this. Good posting. Since we are moving forward the only thing we need to do in order to carve a turn is tip the skis on edge. If we want to steer (skid/brush) we need a third force, to offset the tails of the skis to create a drift. But now comes two options: passive steering or active steering.

In the first case we just initiate a skidding angle to the ski and then retain that skidding angle through out the turn and even it out towards the end so that our skis continue paralell. Here we only need to apply rotation at initiation. A typical way of dooing that would be to pivot our skis by rotating our legs as we up-unweight or we could apply a tiny bit of hip rotation to fuel the initiation or a combination of both. Think medium to large turns on easy terrain. Note that we can change the skidding angle and the turn radius by body balancing movements such as fore/aft balancing or angulation and counter.

In the case of "active steering" we need to initiate the skidding angle at initiation just like in the case of "passive steering" but insted of retaining that same skidding angle through out the turn we keep turning our feet underneath us. However, to do so we need to have something to turn against. This means that we keep our upper body facing down the hill while our feet turn underneath us back and forth. This is done by pointing or cranking our knees from side to side. Some call this tipping. Think short turns down the fall line. Since we are now linking short turns down the fall line and tipping with our feet and pointing our knees back and forth and rotating our femures in the hip sockets we can also use the rebound from previous turn to feed us with momentum and up-force to unweight us at transition making the turn initiation with the pivot very smooth and effortless. No addigional up-extention of the leggs is needed. And since we are facing down the hill with our upper body our leggs will unwind and skis will automatically turn into the fall line as we initiate a new turn.

Note that when you carve any rotation movement will jeopardize the edge locked carve. The problem with teaching oder people carve is that they start every turn with an up-move and rotation. The problem with the new generation of skiers that learned to ski with only tipping and carving is that they have great difficulty in bumps, powder, crud etc. because they cant turn by rotating. As ski instructors we are confronted with both these kinds of challanges on a daily basis.

Quote:
Originally Posted by Jamt

Where is that rotary force coming from?

It could come from femur or it could come from the ground reaction forces (GRF). Generally the more of the forces that come from GRF the better the skiing.

Do you know that it is not possible to provide a continuous torque from the femur to affect the ski? By Newtons third law if you twist the skis you twist the upper body the other way.

Most people who think they are steering by twisting the femurs are not, at least not in the way they think. You can get some temporary change of the force but that is by twisting the upper body the other way. I'd rather call that countering.

You could argue that a carved turn is when the platform angle is larger than 90 degrees. I'd rather call this an edge locked carve. However, not even this definition would be strict because in reality you have torsion along the ski so that tip and tail has a smaller platform angle. There is no finite point where the whole ski becomes carved. What is carving then?

Further in reality the platform angle changes rapidly all the time due to terrain.

I used to have the opinion that a carved turn needed to be edge locked, but due to the above and after reading BTSs motivations in another thread (a long time ago) I changed my mind. I agree with the definition that FOM and BTS have in this thread. It is much more useful.

I was posting at the same time Jamt was. Yes, its correct. People think that they are actively steering through out the whole turn but they are not. We usually just initiate a small pivot at the top of the turn and then we steer by balancing. Not rotating. Even if we did actively counter through out the turn it would probably not affect the path of the skis in the snow directly. Indirectrly it would because our edge angles would increase and cause more friction.

A carve on soft snow where the skis would be drifting a bit in their tracks would still be a carve in my book. I guess a carve could have some skidding/drifting properties to them but there is a huge difference between initiating a turn by edge locked carving or initiating a turn with a skid/brush. Surpricingly many people do not know the difference.

Quote:
Originally Posted by Rick

Race coaches learn to recognize non carved turns where others may not, even versions very close to the line, because it's so crucially important in the pursuit of success.
interesting, because snow and even ice is not cement. It gives way, ever so slightly and at high angles, when you ski at the limit of snow's ability, the difference between edge locked and slightly brushed become quite irrelevant. Where you do what, that is a different question altogether (hint: pressure application makes the difference).

At that level, I call them all carved. Anyways, my prerogative to call them what I want, i guess

P.s. At that level by the way, we carve and brush at the same time, different parts of the ski. What do you call that?

P.s..2 like @oldschoolskier said below (he nailed it so well I had to edit and explain this) I see skiing in terms of edge and body angles, pressure and timing as inputs. Carve or brushing or whatever, is a result and is controllable.

Beginners, sure yeah, they either carve edge locked or not, that's all the difference they can feel. But at the level where I work, which is quite low still, that stuff becomes irrelevant.
Edited by razie - 2/5/15 at 6:00am

There is a really good GIF that I think Bob Barnes did with edge angle, edge pressure and slip.

Quote:

Yes, that is 100% true, but that doesn't discount that there are only two turns.
The physics of a ski on 2d snow is really simple for the most part. There are plenty of websites like this that explain it:
http://www.real-world-physics-problems.com/physics-of-skiing.html

A carved turn only has two forces applied to it, a tipping force to the side, and a forward force to maintain tip pressure.

Any other turn requires a third force, a rotating force. Newtons first law demands it. Once the ski is broken out of a carve it needs a rotary force to change directions, otherwise you would go in a straight linee.

You can call either of these turns anything you want, but due to the force vectors there is only two of them possible.

I lifted my skis, stemmed, and did all sorts of aweful skiing tonight. No one of it in the name of good skiing. I don't think I have skied in such nasty conditions.

Skis self steer to a degree in a skidded turn, but it depends on skier applied rotary force.  First, in creating the skid angle to be used, and second in managing and maintaining that skid angle.  Each requires the active application of skier applied rotary force.  If you're making a skidded turn and stop applying that rotary force you'll revert to carving.  This is how the drill where you steer the first half of the turn and carve the second half is accomplished.  Apply rotary force in the first half, and eliminate it in the second half.

Bob Barnes' "The Complete Encyclopedia of Skiing" defines all this stuff. I don't see why people refuse to use these definitions so we all speak the same language. He even posted a free edition for use here.

http://www.epicski.com/a/the-complete-encyclopedia-of-skiing-epicski-skiing-glossary

But it's worth buying the complete edition.
Quote:

A carved turn only has two forces applied to it, a tipping force to the side, and a forward force to maintain tip pressure.

Any other turn requires a third force, a rotating force. Newtons first law demands it. Once the ski is broken out of a carve it needs a rotary force to change directions, otherwise you would go in a straight linee.

You can call either of these turns anything you want, but due to the force vectors there is only two of them possible.
.
and I shall disagree with that, even if just for fun...

The rock moves straight.... the wire that connects the rock to my finger gets pissed and tight. Since I am strong (well, it was a small rock for this demo), the rock has no other options but to start moving in a circular motion.

The boot moves sideways out of the turn. My leg gets long and then well, tight. The boot has no option but to move on a circular path. My skis are firmly attached to the boot... I.DID.NOT.TWIST.THEM and guess what they do...

Why don't you kick a ball and look at the path of your shoe? And while saying that, I see your problem: you are extending from the turn instead of coming flexed and then letting the feet get long as they tip... Long legs in transition leaves but one option to start a quick short turn: twist them... if that's your point of reference, we can save the arguing....
Edited by razie - 2/5/15 at 6:34am
Quote:
Originally Posted by tdk6

Here is a video I made almost 10y ago on this threads oroginal topic; lifting the inside ski up in the air.

Interesting.  Lifting the tip suggests skiing in the back seat, but I don't see that happening.  The lift is happening right at transition, so there is the momentary appearance of being in the back seat from foot squirt.  Could this suggest even earlier weight transfer, as it is happening before the CoM catches up to the feet?

I've been thinking about some of the explanations I've seen regarding the lifting seen in the Paul Lorenz video.  Is he essentially doing a high performance version of the "Get over it" drill?  I realize hes not doing drills in the video, but the lifting movement seems to be the same with regards to timing and mechanics.

Quote:
Originally Posted by borntoski683

So by your reasoning blue is carving and yellow is skidding, what is the ski equivalent for green where most of us ski most of the time? Please folks these distracting ventures into the English language serve only those who wish to remain ignorant of that green area

Think of it this way.  There is blue (carving), and many shades of yellow (steering/skidding).  There's a distinct line between the two.  Anyone instructor who allows for a degree of skidding in their definition of carving is just a sloppy carving enabler.  Sending students off with the misconception that they're carving when they really aren't.  Illusions of success where it doesn't exist, achievement where it hasn't happened.

I can watch a World Cup racer, and can pick out sloppy carving with skid in it, to degrees that it only makes a couple tenths of difference in a 30 second split time. I can consistently predict the times of the racer because of it.   A distinct line between blue and yellow does exist.  Recreational skiers generally stray way further past that line.  Expanding the definition of what carving is to accommodate those shortcomings just provides them with a false sense of accomplishment.  Commonly known as blowing smoke up their butt.

Quote:
Originally Posted by Rick

Expanding the definition of what carving is to accommodate those shortcomings just provides them with a false sense of accomplishment.  Commonly known as blowing smoke up their butt.

Exactly!
Quote:
Originally Posted by razie

interesting, because snow and even ice is not cement. It gives way, ever so slightly and at high angles, when you ski at the limit of snow's ability, the difference between edge locked and slightly brushed become quite irrelevant. Where you do what, that is a different question altogether (hint: pressure application makes the difference).

At that level, I call them all carved. Anyways, my prerogative to call them what I want, i guess

P.s. At that level by the way, we carve and brush at the same time, different parts of the ski. What do you call that?

P.s..2 like @oldschoolskier said below (he nailed it so well I had to edit and explain this) I see skiing in terms of edge and body angles, pressure and timing as inputs. Carve or brushing or whatever, is a result and is controllable.

Beginners, sure yeah, they either carve edge locked or not, that's all the difference they can feel. But at the level where I work, which is quite low still, that stuff becomes irrelevant.

If we keep it in the context of a groomed slope, the depth of the track will change according to the hardness of the snow, but that doesn't translate to the introduction of skid/steer/brush/smear.

In an earlier post you said that brushed carving deserves a category all it's own because it resides between carved and skidded/steered.  If you watch demos of brushed carves on youtube you will see it often shows skid tracks more than a foot wide.  In my system I call that wide track steering, and it resides waaaaay beyond the line between carving and steering.  My narrow track steering is the closest to carving, with a skid track in some variants of it that are almost invisible.  But it's still steering, feeling way different than carving, and producing much smaller turn radii.

I teach learning skiers early on how to vary their skid angle with great precision.  Quite often in the course of this training they just start carving spontaneously.  At that point they have a full understanding of where the line resides between carving and steering/skidding, and how to skillfully dance around the boundary of that line.

Quote:
Originally Posted by razie

interesting, because snow and even ice is not cement. It gives way, ever so slightly and at high angles, when you ski at the limit of snow's ability, the difference between edge locked and slightly brushed become quite irrelevant. Where you do what, that is a different question altogether (hint: pressure application makes the difference).

number 1 - i haven't quoted myself in a while and I miss that.

number 2 - just like at high speeds you have to leave Newtonian thinking behind and everything becomes suddenly, much more complicated and counter-intuitive, likewise, at high edge angles in performance skiing, you have to leave LeMaster behind and use different thinking.

at high edge angles, even though I have a 90 degree platform or whatever, the snow will give way laterally, given enough pressure. At this point you have different levers and forces you can employ to dig them in and this is why whether the edges are slicing or just barely becomes relevant only in relation to how much you can get out of that snow and what I need at the place that I am in the turn.

@Rick, what you may notice when you see that skidding is the result of other deficiencies or mis-calculations. Carving is a result, not something we do. Show me a WC skier carving 100% of the turn (i.e. bracing against edges dug into the snow) and I will show you a looser in the same photo (no cheating with skiing on the flats and stuff). What I mean is that I don't try to correct said deficiency by saying "carve that better" but by figuring out the underlying cause and addressing that - and it's usually timing, i.e. tactics.

cheers

p.s. I just saw this "skillfully dance around the boundary of that line" and I really like it. That's what I'm talking about...

What happens if you take a skier making a "perfect carved turn" and drop him into a foot of powder?  Will the same turn be carved?

Quote:
Originally Posted by TreeFiter

What happens if you take a skier making a "perfect carved turn" and drop him into a foot of powder?  Will the same turn be carved?

it depends on how high up you take him/her before dropping

Perfect carved turn in WC.

Look harder, at that speed on ice their skis are only on the snow about 70-80 percent of the time when loaded.

edge locked carving is very much its own category, or call it arcing if you like.  By the way, that is the USST definition as well. Shall I quote it again from the USSA manual for the nth time?

Carving action is what happens when the sidecut causes the ski to turn itself, which may or may not be in pure arcing form.  WC racers spend a LOT of time on the course, NOT arcing their skis, yet very much would be considered carving.  If they were arcing everything there would be no no spray and they would sound like a figure skater arcing cleanly across the ice.

So no, I don't agree with Rick and some others that the word carving can only be used to refer to pure arcing.  They are missing the boat.  By isolating pure arcing as the so called only form of carving and lumping everything else into the skid/steer camp they are effectively ignoring use of the sidecut for anything other than pure arcing.  Pure arcing isn't even very useful in practical real world terms.  They are missing the carving boat!

Carving is something the ski is capable of doing, quite obviously so, while arcing purely; but also when not arcing purely.  Carving can be more or less efficient.  With very low steering angles and high enough edge angles, the skis will edge lock and arc on snow that supports it.  With lower edge angles the skis will not quite edge lock, they will develop a bit more steering angle and skid, but the sidecut will still be doing what its designed to do, carve; and so long as the high edges are still pretty high and the steering angle pretty low, the carving action will be pretty good.   As edge angles are reduced and steering angles increased, the turn will become skiddier, though some small amount of carving action is STILL happening.  The scale between pure carving and pure side slipping is not linear.  You don't have to develop too much steering angle with low edge angle before carving becomes extremely inefficient, yet still present in some very small amount.

Carving action from the skis is happening even in the skiddiest of wedge turns.  to ignore this is to be ignorant of how the ski sidecut works.

We can certainly try to draw some subjective opinions about what point of skiddiness would be considered a non-carved turn vs a carved one.  In my opinion, if the ski is making a round turn shape, then there is carving action happening.  we can say a turn is more carvier or less carvier, but its there.  The only truly non carved turn is a side slip, perhaps pivot slips, hockey stops, etc..which aren't really turns at all.  Totally Z shaped turns where the skier makes no round turn shape at all, would qualify for non-carved.  So in actuality, if there is any round turn shape at all, the skis are being carved, perhaps very inefficiently, but still carved none the less.

However if you want to talk about what exactly makes a turn more or less carvey, increases or decreases carving efficiency, that is an interesting discussion and there are definitely certain movements which detract from ski carving, while other movements enhance it.  At some point we can watch a skier making movements which actively detract from carving effectiveness and we can say simply that skier is not carving, even though technically speaking if there is any round turn shape at all, the skis are using some small amount of carving action.  Another skier using movements that actively contributes to helping the skis be more effective at carving can be analyzed as a carving skier, even if they are not technically reaching the utopia of pure arcing, if they are making movements that contribute to optimizing ski carving, then they are carving.

Just to add a little more confusion to this discussion. Where you come down in the carve, not carve issue has a lot to do with how you define the word 'skid' (also 'slip' and 'slide') and whether that definition has negative connotations. So, what is your definition of 'skid? I'm sort of stuck with the traditional ski instruction def of  the tails being displaced at a greater rate than tips and it is basically a defensive braking move and something I want to avoid.

fom

Quote:

A carved turn only has two forces applied to it, a tipping force to the side, and a forward force to maintain tip pressure.

Any other turn requires a third force, a rotating force. Newtons first law demands it. Once the ski is broken out of a carve it needs a rotary force to change directions, otherwise you would go in a straight linee.

Uhm that is simply not true.  The ski reacts with the snow and turns itself.  It does so in pure arcs and it does so when not pure arcing.  No external rotary force is required.  Additionally, in order to exert a rotary force that has any effect on the ski whatsoever you pretty much have to flatten it, which works against carving action in general.  So people who think they have to twist their skis, will find themselves very quickly way way out of the carving zone, I agree with you there but you don't have to be.  Your mis understanding that rotary force is required outside of arcing is where you're missing it clink.

Quote:
Originally Posted by fatoldman

Just to add a little more confusion to this discussion. Where you come down in the carve, not carve issue has a lot to do with how you define the word 'skid' (also 'slip' and 'slide') and whether that definition has negative connotations. So, what is your definition of 'skid? I'm sort of stuck with the traditional ski instruction def of  the tails being displaced at a greater rate than tips and it is basically a defensive braking move and something I want to avoid.

fom

My definition of skid is anything that is not edge locked carving (arcing).  But in my world skidding and carving can co-exist.

To me it makes no difference whether the tail is displacing more than the tips, UNLESS I see specific movement patterns by the skier which is enhancing that effect.  For example tail pushing.

When I see large steering angles, then if there is any carving action happening at all its most likely happening with the tails skidding more then the tips.  Still some carving action is happening.  But its not very efficient and that probably starts to get into the area I would not call the skier a "carving" skier becuase they are working against carving action to end up that way.

In any case I do not see skidding and carving as mutually exclusive.

Quote:
Originally Posted by borntoski683

Carving action from the skis is happening even in the skiddiest of wedge turns.  to ignore this is to be ignorant of how the ski sidecut works.

The side cut only matters when the ski is following it. If you are running the ski diagonally, it doesn't matter at all. Otherwise, I wouldn't have been able to turn straight skis.

Do you think this is carving?

straight skis have sidecuts too sofort99 and yes the sidecut makes the ski turn when its not arcing.  That is what makes a ski even make a turn at all.  that is what makes wedge turns work even.  Its all because of the sidecut.

So you are claiming an absolute straight ski can't turn?
Quote:
Originally Posted by sofort99

Quote:
Originally Posted by borntoski683

Carving action from the skis is happening even in the skiddiest of wedge turns.  to ignore this is to be ignorant of how the ski sidecut works.

The side cut only matters when the ski is following it. If you are running the ski diagonally, it doesn't matter at all. Otherwise, I wouldn't have been able to turn straight skis.

Do you think this is carving?

Two quick points

1. Straight skis weren't straight they just had sidecuts in the 60+ meter range.

2. Any time that a ski is moving forward and is pressured more or less in the center the skis and the ski is anything but dead flat on the snow the sidecut will cause it to generate a force I can use to push my body around. Generally the greater the sidecut the greater the force.

Edited by fatoldman - 2/5/15 at 9:53am
Quote:
Originally Posted by sofort99

So you are claiming an absolute straight ski can't turn?

No, it seems you are?

Actually I'm not really sure your point, but it does seem clear you don't understand how the sidecut works on a ski, both older and modern.

Yeah... using edge engagement and and fore and aft balance to turn the ski and following the side cut are not the same thing.
Quote:
Originally Posted by borntoski683

straight skis have sidecuts too sofort99 and yes the sidecut makes the ski turn when its not arcing.  That is what makes a ski even make a turn at all.  that is what makes wedge turns work even.  Its all because of the sidecut.
Quote:
Originally Posted by borntoski683

Quote:
Originally Posted by sofort99

So you are claiming an absolute straight ski can't turn?

No, it seems you are?

Actually I'm not really sure your point, but it does seem clear you don't understand how the sidecut works on a ski, both older and modern.
Quote:
Originally Posted by borntoski683

... the sidecut makes the ski turn when its not arcing. That is what makes a ski even make a turn at all. that is what makes wedge turns work even. Its all because of the sidecut.

Actually, I'm trying to figure out what you are talking about.
Should have the title changed to " Its all because of the sidecut."
New Posts  All Forums:Forum Nav:
Return Home
Back to Forum: Ski Instruction & Coaching