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Sl and GS turn shapes

post #1 of 19
Thread Starter 
In the equipment forum, someone described a ski having a "bias towards GS rather than SL turn shapes".

Is there a difference in the shape of a modern GS or SL turn. I realize that on the course your line choice is affected by several factors, but is your bread and butter turn shape different in either discipline?
post #2 of 19
This is a good question because the answer is yes and no. When someone descibes a ski having a slalom turn shape - they are likely talking about turn size (radius). Slalom is usually in the ballpark of 9m to 13m and giant slalom is usually around 17m to 24m... all depending on course sets. Now, even though in modern slalom the turns are getting more and more like a GS turn, and some people are arguing that slalom turns are the new standard for all-mountain skiing turns, there are still some movements that are left out of slalom turns in comparison to giant slalom turns. Specifically, one entire phase of the turn.

Slalom skiing almost entirely eliminates the traditional phase three of the turn, which usually is the section of the turn that completes the turn. In slalom the turns come so fast that the edge change becomes almost instantaneous. Using a GS-style transition of any kind will stretch out the transition to the point where you are late, or completely out of the course. The GS-style turn is one that is a more complete turn - probably most reminiscent of the modern PSIA medium radius carved turn - cranked up a few notches in intensity. With the GS turn you have a beginning, a middle, and an end. With a slalom turn you have a beginning and a middle, and then another beginning... The end happens so fast that you barely even know it happened - and you are only know that the end happened because you arrive at the beginning of a turn so quickly. Skiing a slalom course like a GS course doesn't work. Using a traditional cross-over transition makes you late and low - and skiing only arc-to-arc doesn't really work either (because arc-to-arc implies that your turn is 'finsihed').

When I first started racing this was something that I fought. I could ski GS great (as well or better than most 100 point racers), but struggled in even the simplest SL courses. Finally last season toward the end of the season I started free skiing slalom turns behind a 75 point FIS racer. At that point everything clicked for me.

Here is a list of a few enlightenments:
1) Narrower stance
2) No cross-over or up movements EVER
3) Lower body position (not hunched)
4) Face down and constantly move down the fall line while your skis move underneath you.
5) Look forward because the gates come A LOT faster when you do it right

Later

GREG
post #3 of 19
www.sport1.at for videos

I'm willing to bet that the average world cup gs course has an average turn radius of much less than 21 meters.

Generally the radius of a turn on a given ski will be much shorter than the actual sidecut radius. A GS ski with a 21m sidecut radius will carve purely at an absolute maximum of less than 21m. The sidecut radius is significantly shortened when tipped on edge, assuming the ski is decambered. Keep in mind that for any ski, of any radius, the carve radius approaches zero as the inclination angle approaches 90 degrees.

Here's a calculator: http://www.natew.com/frame_main.cgi/...snow/html.Main. Theoretically, a ski with a 25m sidecut radius will carve a 12.5m radius turn at 60 degrees of angle. A small amount of angulation decreases this pretty significantly, to about 8.5m for 10 degrees.
post #4 of 19
Greg,

I would be curious if you have come to a decision? Yes or no?
Seems to me that with your confusion about SL there is no way that you would ever race SL very well.

Regards.


Quote:
Originally Posted by HeluvaSkier View Post
This is a good question because the answer is yes and no. When someone descibes a ski having a slalom turn shape - they are likely talking about turn size (radius). Slalom is usually in the ballpark of 9m to 13m and giant slalom is usually around 17m to 24m... all depending on course sets. Now, even though in modern slalom the turns are getting more and more like a GS turn, and some people are arguing that slalom turns are the new standard for all-mountain skiing turns, there are still some movements that are left out of slalom turns in comparison to giant slalom turns. Specifically, one entire phase of the turn.

Slalom skiing almost entirely eliminates the traditional phase three of the turn, which usually is the section of the turn that completes the turn. In slalom the turns come so fast that the edge change becomes almost instantaneous. Using a GS-style transition of any kind will stretch out the transition to the point where you are late, or completely out of the course. The GS-style turn is one that is a more complete turn - probably most reminiscent of the modern PSIA medium radius carved turn - cranked up a few notches in intensity. With the GS turn you have a beginning, a middle, and an end. With a slalom turn you have a beginning and a middle, and then another beginning... The end happens so fast that you barely even know it happened - and you are only know that the end happened because you arrive at the beginning of a turn so quickly. Skiing a slalom course like a GS course doesn't work. Using a traditional cross-over transition makes you late and low - and skiing only arc-to-arc doesn't really work either (because arc-to-arc implies that your turn is 'finsihed').

When I first started racing this was something that I fought. I could ski GS great (as well or better than most 100 point racers), but struggled in even the simplest SL courses. Finally last season toward the end of the season I started free skiing slalom turns behind a 75 point FIS racer. At that point everything clicked for me.

Here is a list of a few enlightenments:
1) Narrower stance
2) No cross-over or up movements EVER
3) Lower body position (not hunched)
4) Face down and constantly move down the fall line while your skis move underneath you.
5) Look forward because the gates come A LOT faster when you do it right

Later

GREG
post #5 of 19
In Theorie that may very well be. But would'nt you have to factor in also the speed a racer would travel, his/her weight, strength and also skill in order to determine the real radius?

Quote:
Originally Posted by Wassnowboarder View Post
www.sport1.at for videos

I'm willing to bet that the average world cup gs course has an average turn radius of much less than 21 meters.

Generally the radius of a turn on a given ski will be much shorter than the actual sidecut radius. A GS ski with a 21m sidecut radius will carve purely at an absolute maximum of less than 21m. The sidecut radius is significantly shortened when tipped on edge, assuming the ski is decambered. Keep in mind that for any ski, of any radius, the carve radius approaches zero as the inclination angle approaches 90 degrees.

Here's a calculator: http://www.natew.com/frame_main.cgi/...snow/html.Main. Theoretically, a ski with a 25m sidecut radius will carve a 12.5m radius turn at 60 degrees of angle. A small amount of angulation decreases this pretty significantly, to about 8.5m for 10 degrees.
post #6 of 19
Quote:
Originally Posted by simplyfast View Post
Greg,

I would be curious if you have come to a decision? Yes or no?
Seems to me that with your confusion about SL there is no way that you would ever race SL very well.

Regards.
I don't think I understand where you're going with this - care to elaborate?

BTW, I forgot to add the why to the yes and no comment. Compared to old school slalom on straight skis the modern SL and GS turns are quite similar - but in reality they are very different turns and techniques. I will look forward to hearing back from you. I suspect I know what you are going to take issue with... but I also suspect it is a matter of how I worded the above post (not typical racing terminology).

Later

GREG
post #7 of 19
Quote:
Originally Posted by simplyfast View Post
In Theorie that may very well be. But would'nt you have to factor in also the speed a racer would travel, his/her weight, strength and also skill in order to determine the real radius?
My original post was somewhat off-topic... but here goes.

Except for velocity, aren't those extended variables? True, the turn shapes vary a good bit between skiers, which in a course would change the radius. I guess that is the main factor for this thread.

Your ability to carve a tight turn becomes greater at higher speeds, up to a point. That's probably why some people can take such a straight line in GS courses without losing too much speed (as long as it's clean). Of course, it seems that in ski racing that point is passed fairly often. I don't race, though, so I could definitely be wrong.
post #8 of 19
Thread Starter 
Just to clarify, the original question had nothing to do with radius, but turn shape.

If you transcribed the tacks left in the snow from each type of turn onto graph paper, then removed any mention of scale, would the shape be the same? A big circle and a little circle are still circles.
post #9 of 19
With the current techniques of pivots and the like in top-level GS, there is certainly a difference other than mere size. However, even between racers (for instance Rocca and Ligety) there is a difference within a discipline. As technique evolves to match equipment, conditions, course setting, and physical capabilities, it will be very hard to define a "standard" turn for more than a year or so before the definition will have to change.

However, it's all just a series of left and right turns.
post #10 of 19
Quote:
Originally Posted by tief schnee View Post
Just to clarify, the original question had nothing to do with radius, but turn shape.

If you transcribed the tacks left in the snow from each type of turn onto graph paper, then removed any mention of scale, would the shape be the same? A big circle and a little circle are still circles.
Yes. If you look back at your tracks the circles should be constant and end ideally right at the pole where you get off the edge and lunge forward into the next turn. I consider the SL turn to have 3 phases. The initial phase of carving the ski with less pressure followed by heavy pressure in the fall line at the point the arc is going to clear the pole then the release of pressure with the subtle step onto inside ski with forward lunge. I hate to even mention the step since it is easily misinterpreted but that is what they do on WC.

Particularly if you take the skis out of the course then what Tief Schnee proposes is true. In the course you might also have the phenomenom of the skidding upper half with modern GS on "some" turns.

This summer I was forced to always look back at my tracks and so often I would see this J coming around the pole - WRONG - OLDE` - FOSSILIZED

Today driving up to the glacier to run brushes on SLs, "hiking" running brushes, so lots of time to examine the tracks and think about it.

- Fossil
post #11 of 19
Interesting discussion.. To the OP, I would say "yes" there is a big difference. I think the differences we're best summarized by Heluvaskier in that the edge change is much different, mainly due to the difference in body position from Slalom to GS.

It starts to become more obvious with athletes that ski to say 50 points or less in slalom. Their technique is usually defined by a lower hip position, relatively little vertical movement, and an extremely short and incredibly strong impulse. These athletes don't extend as they roll onto a new edge like is done in GS, their legs travel quickly underneath their body to engage the new edge(s). The effect this has on turn shape when drawn on paper is that the arcs from series of slalom turns will be much shallower, and un-connected.

Quote:
Originally Posted by Wassnowboarder View Post
I'm willing to bet that the average world cup gs course has an average turn radius of much less than 21 meters.
I don't know exactly what you're getting at here, but most WC GS courses will be set with 28-32 meters from turning gate to turning gate (pin-to-pin). The thing you must remember is that changes in offset are what make the courses challenging, and force athletes to feather some turns. Men's WC ski lengths are 194+ for GS, and they have turning radii in the 28,29,30m range.
post #12 of 19
Quote:
Originally Posted by Powderhoundin View Post
I don't know exactly what you're getting at here, but most WC GS courses will be set with 28-32 meters from turning gate to turning gate (pin-to-pin).
Well, it turns out that I was wrong about the average gs turn radius. I know it was only vaguely related to the original post. I probably should have started a new thread.
post #13 of 19
Thread Starter 
Thanks for all the input guys, even the tangential stuff. It will give me something to chew on until the snow flies.
post #14 of 19
Tief, if you want t discover the true size of the turns you can consult the FIS course setting rules. Slaom for example changed last year from a standard of 10' across and 15' down (roughly) to about 12' diagonal in terms of gate to gate offset and distance down the fall line. It made slalom courses ski a lot faster (IMO).
Later
GREG

BTW, Mr. simplyfast - still waiting chief :...
post #15 of 19
HeluvaSkier-
Don't you mean 10M, 15M, and 12M respectively? I'm not sure how fast or fun a 12' course would be, as that would be one long flush.

On my small hill for the kids, I'll set a 17M-19M GS course, with an offset of about 3M-5M. Since the kids are running skis with a radius of 8M-12M, it seems like a good comprimise while allowing for more gates and more challenging sets. The kids were tucking top to bottom otherwise. For Masters, we'll usually set a 22M-26M course with a 3M-6M offset. Since nobody is running more than a 21M ski, it works well for the speeds and terrain involved.
post #16 of 19
Thread Starter 
Quote:
Originally Posted by HeluvaSkier View Post
Tief, if you want t discover the true size of the turns you can consult the FIS course setting rules. .......

My Little Blue Book is from 1995. Are they even blue anymore?
post #17 of 19
I figured I may as well post the current setting rules for Slalom and GS since the discussion has gone a bit in that direction..


Slalom
For Slalom, the slalom the distances are measured from "pin-to-pin", or from turning pole to turning pole.

Max distance: 13m
Flush / Hairpins: 4-6m max
Distance between "doubles" in Flush / Hairpins: 75cm (min)


Giant Slalom
For GS the setting is done based on a percentage of the vertical drop from the start to the finish. The number of direction changes must be equal to 11-15% of the vertical drop. The minimum distance between any two gates is 10m.

Therefore the distance between each gate can vary greatly depending on the hill. However, for the most part at the FIS level and above, the setting is in the 26-32m range.

All the above rules can be viewed at www.fis-ski.com or here (most recent blue book):

http://www.fis-ski.com/data/document/ICR04.pdf

Don't forget that the blue book isn't the complete list of rules, you must always check the precisions to see if anything's been added or changed.

One other thing to add is not to forget that most GS skis have radii much greater than 21m. Although some of them are stamped 21m, most are actually stamped >21m, which of course means "greater than" 21m. This is because the 21m ski is actually the shortest of the lengths available for that ski (175 for most FIS legal skis), so as the length increases so does the sidecut radius. Most 190ish GS skis will have radii in the 27m range.


post #18 of 19
Well put

It's interesting how identical GS sets on different hills will ski completely different. Pitch and terrain variations can make a huge difference in how difficult a course is.
post #19 of 19

I was watching the recent Beaver Creek GS again and I love the way the WC skiers aggressively hurl themselves into the turns, like Ligety does here...

 

Click pic for vid

 

Nice discussion of turn technique here.

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