 Poster: A snowHead
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Could anyone give me a few tips on getting a ski to carve a tighter wradius? Should i just buy a ski with a bigger side-cut or can i get my 17 metre radium Atomics to turn quicker? 
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Welcome to snowHeads coowlskierdude,
Put on some weight
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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?
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coowlskierdude, welcome to snowHeads.
If you want to carve tighter turns you need to tip the skis on to a large angle. The more you tip the skis the tighter the turn will be. The faster you go the easier it is to get the skis on to their edges, but the larger the forces will be. To resist and work with those forces you will want to have a "long, strong" outside leg and to shorten your inside leg.
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coowlskierdude,rob@rar is right; the way to make your atomics produce a smaller radius is to get them onto higher edge angles. See link and pic:
http://www.yourskicoach.com/SkiGlossary/Edge_Angle.html
That said, a smaller radius ski, say in the 11 meter range, may make it easier to learn big edge angle carving. They allow you to learn to do it at slower, more comfortable speeds. And,,, no matter how high you get those 17 meter atomics on edge, they'll never be able to produce as small a radius turn as an 11 meter ski can. At similar edge angles, the 11 meter ski will always carve a smaller radius turn.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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rob@rar, FastMan, so when a ski is quoted at 17m turn radius what is that based on? From a geometry perspective I can understand a ski turning a smaller turn the more it is flexed so a ski flexed so that when the ends are closer together (more U like) it will turn tighter than a ski flexed less where the ends are further apart, but I am surprised that just tipping them further over without flex will let the ski turn any tighter than it is geometrically designed to do. What have I missed and where does the manufacturer get 17 metres from if not determined by the arc that the arch cut into the side of the ski shape, i.e. under what conditions will the ski carve a 17m radius arc (turn)?
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You'll need to Register first of course.
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Megamum, i could be wrong but i seem to recall that the "turn radius" is what the ski would carve when on a 10 degree edge angle as per Ricks photo above. at higher edge angles like 45 plus (cant remember the exact angle ) you will carve half the radius
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| Megamum wrote: |
| rob@rar, FastMan, so when a ski is quoted at 17m turn radius what is that based on? From a geometry perspective I can understand a ski turning a smaller turn the more it is flexed so a ski flexed so that when the ends are closer together (more U like) it will turn tighter than a ski flexed less where the ends are further apart, but I am surprised that just tipping them further over without flex will let the ski turn any tighter than it is geometrically designed to do. What have I missed and where does the manufacturer get 17 metres from if not determined by the arc that the arch cut into the side of the ski shape, i.e. under what conditions will the ski carve a 17m radius arc (turn)? |
The radius designation of a ski is simply a measure of the radius of the circle that would be created if the skis sidecut shape was projected into a complete cirlce
In theory a skis radius designation represents the largest radius turn that ski is capable of producing with pure caving, and would be a result of putting the ski on edge at the most minimal of angle possible. Once the ski is tipped further up on edge, the radius of the turn it produced gets smaller, because the ski can now bend more. The turn radius continues to drop as edge angle is increased, until the point at which the ski has been tipped to it's highest possible edge angle. At that point, it's carving the smallest radius turn it's capable of producing. I call that range, from maximum radius a ski can possibly carve, to the smallest radius it can possibly carve, the carve zone. Any turn shape outside the carve zone must be steered.
Now, I'll explain why higher edge angles produce smaller radius turns. Imagine a ski lying on the floor, its center pressed flat to the floor. This simulates a person skiing straight down the slope, engaging either edge. Now, without changing the flex in the ski, tip it slightly up on edge. Because the ski's tip and tail are wider than its center, the center rises off the floor. The higher it's tipped on edge, the higher its center rises off the floor. At the slightest of edge angles that slight rise can be eliminated by pushing the ski almost straight down. It requires very little bending of the ski to accomplish. At a large edge angle the ski's center is higher off the ground, and the direction you have to bend it to allow its center to find the ground again is more sideways, so the amount the ski has to bend to get connected to the ground again is much greater.
On snow, while skiing, the center of the ski does not rise off the snow as edge angle is added. The skiers weight keeps it in contact, auto bending the ski more the moment edge angles grow.
Hope that made sense. It's kind of hard to explain on a key board, and I don't yet have one of my nifty little drawings published that shows this. If you have an old credit card, or a credit card shaped room key, you can cut a curve in one side of it to simulate a ski's sidecut, and experiment for yourself. I keep one in my wallet, in case I need a quick way to demonstrate this principle to a student.
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skimottaret, your 10 percent statement speaks to the reason in my explanation I said "in theory". There's a minimal angle needed to engage a ski and create enough platform for the ski to hold it's edge and turn. It's not a constant figure. It changes according to speed, pitch and snow surface. I'm sure you've done ankle roll turns on very flat terrain, in which all you do is slightly roll your ankle inside your ski boot, and change pressure to the side of your foot, and the ski turns with almost no visible tipping of the ski. That best demonstrates the carve zones max radius for that ski. At higher speeds, on more of a pitch, such a minimalist edge angle would never hold.
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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.
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FastMan, your explanation and photo is very clear, i really like the carve zone idea and explanation.
i think a lot of people hear a ski has a turn radius of X they assume they cant carve turns less than that. I was just trying to make the point that with big edge angles and a loaded ski you can arc roughly half the stated radius which would be your minimum radius.
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All explanations make sense - many thanks. When coupled with my intial question - which appears to have been the correct thing to ask it all adds up to me. My understanding of how a ski turns was fine and now I understand where the radius comes from it makes even more sense. I guess in theory, because you need some edge somewhere to turn a ski. the exact radius turn as defines by the arc cut on the ski can't actually be made. This is because, if I understand the above explanation it will always be marginally less as there will always a marginal flex in the ski if it is turning with the weight of a skier on its edge so lessening the actual curve of the ski on the snow.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Megamum, bravo!
skimottaret, I would imagine your minimum radius estimation would be in the ballpark.
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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.
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FastMan, I dont want to get too anal about the definition but it is bugging me... i am sure i heard that there is a common standard that defines how turn radius on a ski is determined. FIS must have one as they enforce min radius depending on event, perhaps that is where i heard the 10 degree thing. Then again it may just be the minimum radius of the side cut as per your diagrams and i am talking nonsense. If i remember where i saw it i will pass it on as it would be useful to add to any definition or glossaries.
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You know it makes sense.
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Sideshow_Bob, thanks, sounds like i was talking nonsense re the 10 degree thing and that it is just the physical side cut of the the part of the ski (roughly) that contacts the snow that they measure
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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Is a sidecut always symmetrical? By that, I mean is the radius always consistent along the arc?
EDIT - I know it would have to be in order to be an arc but you know what I mean 
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Poster: A snowHead
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tiffin, I don't know for certain, but I think I've read that in some cases it isn't, but I don't know, if that is the case, how they then specify it.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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From the Scott website:-
"Dual Radius
Traditional skis have a fixed radius that determines the length of every turn. Scott skis combine two radii (dual radius) to create the sidecut or “shape” of the ski. By incorporating the Dual Radius concept, the ski can turn when you want it to turn, the result is a more versatile ski which is not confined to one type of skiing or terrain."
Whatever that means. 
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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?
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| Quote: |
Whatever that means
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very simple, surely. The skis are assymetrical - when you turn left, you swoosh round with tight radius, when you turn right, it's a great big GS turn.
They are also twin tipped and have reversible bindings, so if you get fed up with tight turns to the left, you take them off, swivel the bindings 180 degrees, and bob's your uncle.
Can't think why they didn't think of that before.
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You need to Login to know who's really who.
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pam w, gosh that's so clear to me now. All these years I've been skiing on skis which turned when they wanted to and not when I wanted them to. Must have been a commie plot. Glad the yanks have come to my rescue.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Yoda, I've seen snowboard designs where the edge radius is not constant, it changes along the length. Can't remember which way it goes, but I guess less at the tip\tail, tighter in the middle.
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You'll need to Register first of course.
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Megamum, here you go:
[img]http://www.fischerskis.com/upload/cached_images/_upload_en_product_technologies_en_product_technologies.00002521.pic_6e525355dcd490401cc4e7b68779056b.img?1259844394[/img]
Anyone fancy complicating this further with reverse sidecut? 
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Hmm, maybe no embedding then!
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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.
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Getting the most out of that ski requires good fore/aft balance skills.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| coowlskierdude wrote: |
| Should i just buy a ski with a bigger side-cut? |
wsnowblades should do it... 
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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.
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There is so much confusion caused by this.
To a very large extent, all the manufacturers numbers are pure marketing.
It is a ski side-cut radius, NOT a turn radius.
Equaly important, if not more so, is the longitudinal and torsional stiffness of the ski.
The figures relate to the ski in inverse camber. The stiffness tells you how easy it is to achieve that, and how easy it is to bend the ski beyond that.
Hence it may be easier to do tight turns on a soft ski with a large side-cut radius, than on a stiff ski with a short side-cut radius.
Then there is the tip & tail geometry & stiffness.
The tip geometry determines how easy it is to initiate a turn on an edge.
The tail properties affect how you finish a turn, easy release to a skid, or tightly held to the edge.
Then there is the overall width of the ski, not just at the waist.
This affects how easy it is to transfer from edge to edge, with the tip dimensions being as important as the waist.
This explains why really fat skis are only any use in powder.
Great if you are a sponsored rider with a helicopter, or just like posing in the cable car, useless otherwise.
Then there is the weight of the ski / binding combination.
Overall swing weight, and weight of large tips, can seriously alter your performance & enjoyment.
Ski stiffness also needs to relate to your weight & skiing style.
I used to race to quite a high level on a soft ski, because I am very light & couldn't bend a stiff ski.
The real answer is to find your equipment guru in a ski shop.
He /she will match your physical attributes / skiing style / how much you want to pose / budget to an appropriate ski.
Don't get too wrapped up in all the figures.
They mean a lot less than the manufacturers would have you think.
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FAQ
