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What's essential for carving on hard snow?

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Chris V.

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LiquidFeet, I believe that's a good summary.

But I think your #4, "Skis need camber and parabolic shape," would benefit from discussion. A lot of intermediate skiers have a misconception about why skis carve, or why they turn at all other than insofar as a straight, stiff two by four can turn by skidding. A shaped ski doesn't turn along the sidecut when placed flat in the snow. To make our skis engage in a carve, we have to bend them while they are tipped on edge. The radius of the carved turn is defined by the amount of the bend in the skis.

So...it comes down to, how do we get our skis bent in the amount needed for a turn of the desired radius? Some factors that go into this:

o The amount of sidecut in the skis. A deep sidecut strongly promotes bending of the skis, because when such skis are placed on edge and force is applied to their centers they need to decamber a lot before the edges under the boots contact the snow. Still, skiers have been carving for a long time. Thirty or forty years ago, skis were much straighter--nevertheless, they had a little sidecut to work with. (See the comments by Francois Pugh.)

o The degree of stiffness of the skis. Too stiff a ski will not bend enough. Too soft a ski will be noodly.

o The amount of camber in the skis. Camber creates a resistance to bending. Skis with a reverse camber end to end, or only in tips or tails, lack that resistance in that part of the skis. This doesn't mean that they're incapable of having the edges engage strongly and carve, but it all goes into the equation. Big early rise plus soft ski is going to mean noodly. (See the comments by epic, Philpug, and Francois Pugh--the last noting that with tip rocker, the ski must be tipped far enough to engage the tips.)

o The skier's mass. (Light skiers should consider putting rocks in their pockets.)

o The speed at which the skier is moving. Greater speed translates to greater centripetal force which translates to bending the skis more strongly.

o The angle to which the skier tips the skis.

Every ski has a "natural turning radius" that gets advertised and stamped onto the graphics. But the radius that the ski actually carves depends on a lot of factors. I would say that each combination of ski and skier presents a range of possible turning radiuses. It's not unlimited, but it's a range that the skier can work with.

What else can we do to adjust the radius of a carved turn? Direct greater downward force to the tips of the skis to differentially create a greater bend in the tips?
 
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KevinF

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We just also need to consider the athleticism required to put up with the pressures of a real SL carved turn on ice - the one snow condition that throws the most energy back into the skier - all other snow is softer and easier to control speed on.

Happy new year, all!

Last year I was on my FIS slaloms doing my best imitation of arc-to-arc carving on an easy blue (Nosedive below National). It was going well and I was feeling huge energy out of my skis.

Until I got launched out of a turn and came entirely too close to the trees before I saved it. I shut it down in a big hurry.

To your point, the forces being dealt with after just a few “edge locked” turns very quickly gets to a level very few can deal with.
 

Chris V.

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The great thing about the English language is that we're all free to define words to mean whatever we want. I'd probably choose to define pure "carving" as turns in which the tails do not displace at all from the pathway followed by the tips, and which thus leave clean railroad tracks in the snow. In this video, I think you'll see that the skier isn't always leaving clean railroad tracks. Which is not to say that it isn't great skiing. There's certainly a place for impure carving. As it gets steeper, it becomes rare that a run is wide enough that we can get the desired speed control solely from turn shape, that is from continuing each turn uphill until we slow down.
 

Dudeabides

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Steepest groomed in Austria is 38-41deg. Depends who's measuring I guess and the snow?
Full on carving on a 40 deg slope? Not a lot of people have the skills and nerves to do more than 1 turn. Speed builds rapidly.

The key is trying to carve up the hill more or less... speed definitely builds quick but it levels off if you really finish your turn. It's a great way to cheat your hip to the snow as you don't have to go as far ^^,
 

Chris V.

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What jumps out, in the more extremely "stivoted" turns, is that the skier is initially throwing the skis sideways to MORE than the eventual steering angle. The skier then backs away from this, to a more modest redirection of the skis. The initial sideways move is entirely a speed reduction tactic!
 

ADKmel

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railroad tracks.jpg
 

François Pugh

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It is really simple phisics. Mgh converts to V^2/2g. With friction of a cleanly carving ski being the only loss, unless you have enough room to turn uphill you reach a speed where a 13 m ski tipped suficiently to resist the turn force wiĺl dial up a turn radius that provides a V^2/r that cannot be resisted at that tipping angle and the pure carve will deteriorate.
Typically, on a narrow black run where you are not the only skier, skiing uphill is ill advised, although still possible.
 

James

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The key is trying to carve up the hill more or less... speed definitely builds quick but it levels off if you really finish your turn. It's a great way to cheat your hip to the snow as you don't have to go as far ^^,
True, but I should have included "handle the forces" along with speed and skill. On a 40 deg pitch the forces to hold a carve up the hill will be very large.

How often do they do pure carves in racing?
Slalom skiers almost never ski arc to arc. It's on then off. Maybe for a brief period back in the 2000's when men were still on 155's and slalom was a mini gs.

In the wcup downhill or superg from Bormio the course was amazingly bumpy. Not just the rollers, but surface bumps that constantly rattle the skis and feet. Even if you were say csrving a turn, the surface was such that the ski is off the snow a significsnt percentage of the time. It couldn't possibly come down in the same pencil line.

Btw, Dharon Rhslves, a light guy for a speedskier, didn't need rocks in his pockets to win the Hahnenkamm.

An interesting aside on Rhalves first win:
--------------------
The second breakthrough was in 2000, again in Kvitfjell, when he achieved his first World Cup downhill win. “I’d been home in California before the Kvitfjell race and just spent three amazing powder days with freestyler Jonny Moseley and extreme skier Shane McConkey. When I arrived in Norway, I just concentrated on having fun and playing on my downhill skis like I’d been doing in the powder.” Whatever he did, it worked, and gave him the confidence to beat the best in the world that day.
----------------------
https://www.telegraph.co.uk/travel/...-interviews-american-ski-racer-daron-rahlves/
 

Eleeski

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LiquidFeet, I believe that's a good summary.

But I think your #4, "Skis need camber and parabolic shape," would benefit from discussion. A lot of intermediate skiers have a misconception about why skis carve, or why they turn at all other than insofar as a straight, stiff two by four can turn by skidding. A shaped ski doesn't turn along the sidecut when placed flat in the snow. To make our skis engage in a carve, we have to bend them while they are tipped on edge. The radius of the carved turn is defined by the amount of the bend in the skis.

So...it comes down to, how do we get our skis bent in the amount needed for a turn of the desired radius? Some factors that go into this:

o The amount of sidecut in the skis. A deep sidecut strongly promotes bending of the skis, because when such skis are placed on edge and force is applied to their centers they need to decamber a lot before the edges under the boots contact the snow. Still, skiers have been carving for a long time. Thirty or forty years ago, skis were much straighter--nevertheless, they had a little sidecut to work with. (See the comments by Francois Pugh.)

o The degree of stiffness of the skis. Too stiff a ski will not bend enough. Too soft a ski will be noodly.

o The amount of camber in the skis. Camber creates a resistance to bending. Skis with a reverse camber end to end, or only in tips or tails, lack that resistance in that part of the skis. This doesn't mean that they're incapable of having the edges engage strongly and carve, but it all goes into the equation. Big early rise plus soft ski is going to mean noodly. (See the comments by epic, Philpug, and Francois Pugh--the last noting that with tip rocker, the ski must be tipped far enough to engage the tips.)

o The skier's mass. (Light skiers should consider putting rocks in their pockets.)

o The speed at which the skier is moving. Greater speed translates to greater centripetal force which translates to bending the skis more strongly.

o The angle to which the skier tips the skis.

Every ski has a "natural turning radius" that gets advertised and stamped onto the graphics. But the radius that the ski actually carves depends on a lot of factors. I would say that each combination of ski and skier presents a range of possible turning radiuses. It's not unlimited, but it's a range that the skier can work with.

What else can we do to adjust the radius of a carved turn? Direct greater downward force to the tips of the skis to differentially create a greater bend in the tips?

"Ski bending"? Ice skates don't bend yet carve ice spectacularly. A small amount of slippage from having the ski (or skate) not bent into perfect alignment with the turn is irrelevant. As long as the edge can be engaged in a wide enough stance to offer stability, the ski will carve on ice. Most real world experience will find the stiffest ski will be best on ice - no bending nuances. Carved arcs flow with the hill and the obstacles not some numbers on the ski spec.

Visualizing the ski bending is great for instruction and understanding proper form - even if it is not a perfect reflection of reality.

But real skiing is not pure carving. So maybe "pure" carving is all these fancy theories. I just want to enjoy the ride down the hill.

Eric

.
 

dbostedo

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"Ski bending"? Ice skates don't bend yet carve ice spectacularly.

I was under the impression that skates already have a bit of vertical curve (rocker, in ski-speak) which makes them turn when tipped. Maybe I'm mistaken. Can a perfectly flat skate still carve? I don't see what would make it turn when tipped if it was a perfect straight-edge.

EDIT : And I think ski bending is absolutely required to carve. And stiffer skis hold best once they are bent, probably because of the torsional stiffness which keeps the entire engaged edge from flapping and disengaging.
 

Eleeski

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My old figure skates had a huge flat spot to carve with. My rollerblades have no rocker but still can be forced into smooth arcs.

Skis with camber that don't bend (I built a pair) will carve on ice. They just didn't do much else and were horrible skis.

Eric
 

razie

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It is really simple phisics. Mgh converts to V^2/2g. With friction of a cleanly carving ski being the only loss, unless you have enough room to turn uphill you reach a speed where a 13 m ski tipped suficiently to resist the turn force wiĺl dial up a turn radius that provides a V^2/r that cannot be resisted at that tipping angle and the pure carve will deteriorate.
Typically, on a narrow black run where you are not the only skier, skiing uphill is ill advised, although still possible.

You don't need to turn uphill to control speed... how many here need to ski uphill to maintain a carving turn shape?

Friction by heat is not the real speed control mechanism... bending the tip is.

Here is an example on a blue run, a kid - it was the first run of the day so he was just warming up -not putting in the full effort to sustain this- but we can clearly see that he is maintaining a given speed, even if only for a few turns:


This was the worst conditions I have ever been on, boilerplate with a sprinkle of fluff, where the ski did not even leave a mark. From a few hundred lower skilled racers, only a couple were able to cleanly carve it.

Also, if you look at heluva's videos, they are mostly on a steep black run, which is almost always injected, i.e. ice.

Even I can do this for a few turns on a black run and I am far from athletic - this was many years ago:


It is very technically taxing and few can do it, you have to have very good technique in each turn: as soon as you're off the tips by even a little, it's over, your physics takes over and you throw them sideways, which you see happen above.

Here is how it works - the speed control mechanism quite visible here (he is chopping off the top of a few turns, but just a tiny bit and we can ignore that - that is not the speed control mechanism here nor does it change the carved turn shape meaningfully)...


There are quite a few eastern skiers here, we don't need to discuss this subject only at a theoretical level....
 
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jack97

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You don't need to turn uphill to control speed... how many here need to ski uphill to maintain a carving turn shape?

Friction by heat is not the real speed control mechanism... bending the tip is.

QFT...... some how this technique (bending the tip) became a lost art.
 

François Pugh

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A few turns on a blue is no problem. GS on a wide black run is no problem. For SL skis on a narrow black, mgh=1/2 m v^2 -friction (including ski-ice air and internal ski friction) results in a speed too high for a sl ski to carve pure arc to arc turns after about a half dozen turns ( more turns if your skill level is not up to carving pure edge locked turns) .
You can control your speed by making tighter turns, by delaying the time at which you release your body (Not skis) from the turn and by more emphasis on forcing a bend in the tips than getting a driving force from the tails. However, there is a limit on how much energy you can dump while carving by the op definition without uphill body movement, a limit likely to be reached on a narrow icy black run by those of us who are forced to obey the laws of physics. That limit will have a 13 m ski above its design speed. You may think you are still carving arc-2-arc beyond that limit, and you will still be ripping turns, but the turns will be ripped, not cut.
 

skier

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Not true. Physics and reality says that the ski edge bites and turns as soon as it is put on edge.

"In our earlier discussions of the carved turn, we assumed for the sake of simplicity that the ski carved uniformly throughout the turn. Field observations of even the most accomplished skiers indicate that this cannot be true. Even the most purely carved turn must involve some skidding." The Physics of Skiing, pg. 37.

They go on to break down the turn into three sections, "the skid stage", "the early carve stage", and "the advanced carve stage". The amount of skidding is greatest at the beginning of a turn which matches the concept of the critical edge angle. Also, I believe the necessary amount of skidding will be more on a hard surface.

The implications of this are kind of astounding. The perfect carve turn is not something that is accomplished merely by the physics of tipping a ski. Tipping the ski to get a perfect arc is an oversimplification of a very complex physical problem. But, this false conclusion has led to the impossible combination of defining expert skiing as creating a perfect arc with no rotary input. Come on, tipping the ski and balancing on the arc is easy. For some reasons those simple and effective movement patterns elude intermediate skiers, but it's not hard to do. What's hard to do is ride the arc on a hard surface and not skid. This is because skidding during the turn is part of the natural physics of how the skis work.

I can only conclude that it's become like the Emperor's new clothes. Whoever recognizes skidding in their own skiing must have low skill similar to whoever sees the Emperor as naked must be incompetent. Therefore, people who have the proprioception to recognize the truth are often silent. On the flip side, I've often seen how people are unable to recognize skidding and/or rotary input in their own skiing or in videos. Creating a perfect track is probably so hard, because there must be movements involved that people are failing to analyze, describe, and teach. Skiers go out trying to tip and ride, letting the ski do all the work refusing to steer since that's "inferior skiing", but instead of the perfect arc, they get what the ski's natural design allows. I can imagine after trial and error, some stumble onto the exact combination of tipping and steering that gives a nice track in some circumstances without even being aware of what they are actually doing.
 

Erik Timmerman

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I don’t know what your black trails look like, but on our black trails I don’t even want to try and carve unless there is B-net.
 

Dudeabides

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QFT...... some how this technique (bending the tip) became a lost art.

Bending the tip shortens the radius and points you uphill faster. I'm not saying turning up the hill is the only way to control speed while maintaining a pure carve on very steep terrain, but it certainly is a way.

Edit: Also, literally turning up the hill is a bit of an exaggeration, but cranking the end of a fast carve can feel like it.
 

dbostedo

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My old figure skates had a huge flat spot to carve with. My rollerblades have no rocker but still can be forced into smooth arcs.

Skis with camber that don't bend (I built a pair) will carve on ice. They just didn't do much else and were horrible skis.

Eric


I'm pretty sure a perfect straight edge won't turn just from tipping if it can't bend (i.e. won't carve) on ice or snow. @Eleeski there must still be something going on with your skis that won't uncamber, between the shape of the edge and sidecut, and the contact points causing some kind of flex or curve, even with the ski still cambered. On a rollerblade, I'd think the shape of the wheels is what makes you turn just by tipping, but I haven't rollerbladed in many years.
 
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