 Poster: A snowHead
|
| veeeight wrote: |
| all my colleagues and several WC coaches are completely wrong. |
You're not impressing me; I have known many World Cup ski coaches over the years. A detailed understanding of Euclidean geometry and Newtonian physics, and how it applies to skiing, was not always their strong point! 
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
rayscoops, Bang on.
| Quote: |
1. The inside shin has a very slightly greater edge angle than the outside shin - almost too small to be visible with the naked eye.
This is biomechanically impossible at high edge angles - how can you create an O frame during max inclination/angulation? Plus - by doing that you will create inside ski divergence, not a smaller radius
2. Extra tongue pressure produces greater ski flex at the shovel of the inside ski, creating a tighter radius for a given edge angle.
I agree that you have to try and bend the inside ski more, but extra tongue pressure on the inside ski? So you will need zero, or negative tip lead to get a tighter radius than the outside ski?
|
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
rayscoops, 
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
|
|
|
|
|
|
veeeight, the arcs plotted on that graph are not parallel. The data clearly shows divergence and convergence.
|
|
|
|
|
|
|
|
Sorry, guys, I haven't read the whole thread. And sorry again, I don't intend to. But from my reading of this page I'll offer my 2 cents. Probably has been said already, but here goes.
What we're seeing here is a disconnect between what math says is necessary, and the perception of what V8 and his friends see and feel happening on snow. You guys siting the math behind the skiing, that the inside ski travel on a shorter radius arc than the outside ski: yep, that pretty obvious even to the most neophyte mathematician, and I'm sure V8 is not debating that. The question then, is HOW it is that V8's skiers appear to be laying down 2 cleanly carved tracks, while no noticeable higher tipping of the inside ski is taking place, and they swear they feel no steering of the inside ski happening. OK,,, stage is set,,, here's comes my bit.
The difference in tip angle needed between inside and outside ski/leg to produce a totally clean carve on both skis is pretty minimal. We're talking about, say, a 15 meter radius vs. a 15.25 meter radius. I'll leave the math to others do, and perhaps somewhere in the prior 18 pages it has been done, but my guess would be only 1 or 2 degrees of tipping angle difference, at most, would be needed to compensate. While the perceptions top level athletes possess of what is happening while they ski is fantastic, they can't distinguish a one or two degree difference between of tip angle of the inside and outside leg, anymore easily than they can distinguish the difference between balanced 90 and 92 percent on their outside ski. A skilled skier can/will intuitively make that adjustment, and not even realize he/she is doing it. And the outside observer of that skier would be just as hard pressed to see that one or two degree tip difference in such a dynamic setting.
Now lets "suppose" the skier is using equal edge angles, or even slightly less angle on the inside ski. If you go to Lemaster's site and view his montages you will see many examples of obviously less edge angle on the inside ski. These guys are on mega big edge angles at which body mechanics make it difficult to maintain symmetry in the amount of tip angle. So how do they keep their skis tracking parallel? Two methods. The first is the divergence of the inside ski I've spoke of before, and I see some of your referring to. Here, the skier manually turns the inside ski in a little bit at the beginning of the turn such that it will not have to make as much turn as the outside ski, and produces the extra foot separation needed at the apex of the turn. Another look at Lemaster's site will show some examples of this being done.
But lets say that is not happening. The other method of keeping the skis tracking parallel when the inside leg tip angle is equal or less is called rotational tension. By keeping the inside leg somewhat tensioned and resistant to being twisted out of rotational alignment with the outside leg, force can be transmitted down to the ski that forces it to micro steer and remain in directional harmony with the turn shape dictating outside ski. The amount of this micro steering needed is dependant on the difference between the tipping angle of the inside and outside ski/leg. At equal edge angles it would be miniscule, and over the course of an entire turn would be all but impossible to see in the track of the skier, or be felt by the skier. It's tool WC racers use to compensate for the difference in tip angle at high edge angles, to keep their skis tracking parallel. The more the tip angles differ, the more this compensation technique will become apparent to the eye, and in the track. You can experiment with this on snow yourself. Make an assortment of turns with different tipping angle discrepancies, and notice how it shows in the track.
Hope this helps to resolve some of the debate, and explain what may be happening. V8 can very much be seeing what he's seeing,,, his athletes can very much be feeling what they're feeling,,, and the mathematicians can at the same time be very right.
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
| rayscoops wrote: |
| theory, geometry and science is best kept in class room |
In which case I've got an unlimited pass to the Tacoma Narrows Bridge I can sell you  You can even buy my Firestone 500-shod first-edition A-class Mercedes to drive across.
|
|
|
|
|
|
|
|
FastMan, he set out in stone what he was saying.
1. Identical arcs.
2. In perfect parallel.
3. With identical ski angles.
What you have outlined is pretty much what we've been saying about micro adjustment. From the maths side, we are not saying it doesn't feel or look right. For pity's sake, he was even saying that the inside rail of a turning rail track was geometrically identical to the outside one!
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
| Quote: |
The difference in tip angle needed between inside and outside ski/leg to produce a totally clean carve on both skis is pretty minimal. We're talking about, say, a 15 meter radius vs. a 15.25 meter radius. I'll leave the math to others do, and perhaps somewhere in the prior 18 pages it has been done, but my guess would be only 1 or 2 degrees of tipping angle difference, at most, would be needed to compensate. While the perceptions top level athletes possess of what is happening while they ski is fantastic, they can't distinguish a one or two degree difference between of tip angle of the inside and outside leg, anymore easily than they can distinguish the difference between balanced 90 and 92 percent on their outside ski. A skilled skier can/will intuitively make that adjustment, and not even realize he/she is doing it. And the outside observer of that skier would be just as hard pressed to see that one or two degree tip difference in such a dynamic setting.
|
Thank you, FastMan. You nail the mis-conception right on!
If one is to draw two lines, one 30 degree from horizontal and one 31 from horizontal, put them next to one another, everyone without a compass and ruler would swear the two are "at the same angle", or "perfectly parallel". That's what we're seeing in the top athlets, who carves perfect railroad tracks with seemingly perfectly parallel shine without violating the laws of methematics.
If the understanding of meth helps the understanding of skiing, all the power to the instructor. For the rest, who're less gifted in meth and more talented in skiing, JUST DO IT! There's quite a lot can be learned by "follow me". Trying to bend the rule of meth or say the meth doesn't apply, now that's not going to help ANYONE.
|
|
|
|
|
|
And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
|
| PJSki wrote: |
FastMan, he set out in stone what he was saying.
1. Identical arcs.
2. In perfect parallel.
3. With identical ski angles.
What you have outlined is pretty much what we've been saying about micro adjustment. From the maths side, we are not saying it doesn't feel or look right. For pity's sake, he was even saying that the inside rail of a turning rail track was geometrically identical to the outside one! |
My part 2 compensation method can explain the occurance of the 1,2,3 scenario. I have nothing to explain your highlighted statement.
|
|
|
|
|
|
|
|
| abc wrote: |
Thank you, FastMan. You nail the mis-conception right on!
If one is to draw two lines, one 30 degree from horizontal and one 31 from horizontal, put them next to one another, everyone without a compass and ruler would swear the two are "at the same angle", or "perfectly parallel". That's what we're seeing in the top athlets, who carves perfect railroad tracks with seemingly perfectly parallel shine without violating the laws of methematics.
|
Thanks, ABC, for consolidating that part of what I saying to an even clearer to understand version.
|
|
|
|
|
|
You know it makes sense.
|
|
|
|
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
|
Thank you FastMan, that is exactly what a number of us have said time and time again (and your ears should have been burning red hot, as I've been citing you in support of this on many occasions - in the hope that he would listen to that, since I'm clearly not a good enough skier for anything I say to have any credence). Unfortunately it's also what he's rejected time and again - and he still clearly hasn't grasped the concept of measurement accuracy and tolerances.
| veeeight wrote: |
| The outside ski will very often prescribe a smaller radius than the inside ski. |
yes, as has been agreed many times, but you still miss a crucial bit necessary to complete the sentence and the concept..."for part of the turn"
|
|
|
|
|
|
Poster: A snowHead
|
It's also worth remembering some of the complete and utter gobbledygook that has been put forward.
| Quote: |
| Much of the assumption that the inner ski tracks a smaller radius than the outer ski is because you are treating it like a circle with the centre as a fixed/static point - but when you're skiing the centres of the tracks are moving with the arc - thus immediately making it entirely possible that the two tracks produced by inside and outside ski are, in fact, of the same radius and are doing the same thing. |
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
| GrahamN wrote: |
| veeeight wrote: |
| The outside ski will very often prescribe a smaller radius than the inside ski. |
yes, as has been agreed many times, but you still miss a crucial bit necessary to complete the sentence and the concept..."for part of the turn" |
So why are people still banging on about the inside ski having a tighter radius then?
|
|
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
| veeeight wrote: |
| So why are people still banging on about the inside ski having a tighter radius then? |
As far as I understand the geometry, that only applies if the skis are purely parallel.
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
|
If it didn't have tighter radius, you'd get convergence of the skis.
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
| veeeight wrote: |
| GrahamN wrote: |
| veeeight wrote: |
| The outside ski will very often prescribe a smaller radius than the inside ski. |
yes, as has been agreed many times, but you still miss a crucial bit necessary to complete the sentence and the concept..."for part of the turn" |
So why are people still banging on about the inside ski having a tighter radius then? |
Because you wanted the tracks to be parallel. The case of outer ski describing a tighter arc for part of the turn - during which time the tracks will rapidly reduce divergence or increase convergence - has already been considered on page 5, page 7, again and probably a few more times subsequently. Do please pay attention.
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
| laundryman wrote: |
| veeeight wrote: |
Conversely: It's more useful to think of ski tracks as segments of arcs (as your imaginary centre/s are moving alongside the arc, you are never skiing about a fixed point inside a circle):
All four lines are exactly identical. It would appear from the top diagram that the inner line has a smaller radius that the outer line.
But in the bottom picture I've nestled up the two lines close together, and as if by magic, with a little visual imagination, they overlap (well they should do as they are all identical). They are of the same radius.
Your left ski has an identical sidecut radius to your right ski. In a park and ride situation, wheren you just tip the ski over to the side, both skis are describing identical arcs - but because they are displaced by a certain distance apart, this gives rise to the illusion that the inside track is a smaller radius. |
v8, presumably you can see that those curves aren't parallel. |
And he never did answer this question.
So, V8, are the lines in the above diagrams parallel, in your opinion?
|
|
|
|
|
|
|
|
I just cannot believe you guys have been sucked into this again! 
You know you're right. Everyone posting has agreed that you're right. Isn't that enough? Look, if you're waiting for him to say, "Yes, you've convinced me, you're right after all", he won't. Will you argue for ever?
Look. Just pretend you're a woman. Smile and say, "Fine, whatever". Then go and do something more interesting instead. I promise you, the sky won't fall in, you won't drop dead, nothing will happen except you will be free of it.
And you'll still be right! 
|
|
|
|
|
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
I"m happy I'm right, I"m happy for people to ski according to 2D geometry if they want! There's no problem as far as I can see/ski!
They have to respond because they know there is more to it than 2D geometry, and they also know that it's not what happens in real life skiing!
They probably believe that when you carve a 360 degree turn in the snow, it forms a circle!!!! 
But maggi, you're right, enough of this internet ping/pong. I'm off to carve some non diverging nor converging lines. Which apparently is impossible without making my inner ski carve a tighter radius.
Last edited by You'll get to see more forums and be part of the best ski club on the net. on Thu 5-06-08 11:27; edited 1 time in total
|
|
|
|
|
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
|
|
|
And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
|
veeeight,
| Quote: |
there is more to it than 2D geometry
|
Gosh. Hold the front page.
|
|
|
|
|
|
|
|
|
|
|
You know it makes sense.
|
|
maggi, but I'm not saying he's wrong! That profound observation is, of course, spot on!
|
|
|
|
|
|
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
|
|
Anyone got any ideas on solving 3rd world hunger?
|
|
|
|
|
|
Poster: A snowHead
|
|
This is snowHeads gold.
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
| Quote: |
I'm off to carve some non diverging nor converging lines. Which apparently is impossible without making my inner ski carve a tighter radius.
|
and for an encore Veeeight goes on to prove that black is white and gets himself killed on the next zebra crossing.
Apologies to DNA
|
|
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
|
Kramer, i still cant believe this has gone onto 20 pages and has been probably the most read thread on BZK's
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
|
skimottaret, no one actually reads it, we just skim read the insults
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
| veeeight wrote: |
| I'm off to carve some non diverging nor converging lines. Which apparently is impossible without making my inner ski carve a tighter radius. |
Well, it IS impossible. Though apparently you can't tell the difference.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
|
|
|
|
|
|
|
|
|
|
FAQ
As opposed to draw curves on paper 
