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Define GL and SL turns

post #1 of 17
Thread Starter 

I am not a theory guy, but can someone help me put in writing the general definition for GL ans SL truns? I need this for some school boys that are going to ski next week.

 

I kinda have an idea of what people mean by that but since I haven't heard this term in Europe so often I don't want to give the wrong information to the kids

 

We want to give them some general theory before they hit the slopes.

 

Thanks

post #2 of 17

I'm assuming you mean SL and GS?

 

SL = slalom

GS = giant slalom

 

Unless they are racing, why does it matter?

post #3 of 17

You could make it a basic geometry lesson.  Modern SL skis are designed for the tighter turns you encounter in a slalom course and have a radius somewhere around 12 meters or less.  GS skis are designed for the Giant Slalom event that is skied at faster speed using wider turns.  I think they use about a 17 meter radius ski.  Racers please provide more specifics, but don't muddy the water with cheater side cuts pleez.

 

Simple version SL=tight little skinny turns.  GS=high speed wider arching turns.

post #4 of 17

GS skis currently are running a 27m turn radius, up from 25m which is up from 21m... longer faster turns.

 

They are two different ski racing events, they have nothing to do with beginner skiing, so you really shouldn't confuse things by bringing it up.

post #5 of 17

The question wasn't how a SL ski was different from a GS ski, but how a SL turn was different from a GS turn.

 

Quick and dirty answer:

 

Short, quick turns vs long, swooping turns.

 

A more technical answer to the question can be found in the FIS rulebook, describing how a SL course should be set, vs how a GS course should be set

 

Slalom:

 

802.1.2 The ideal slalom course, taking into consideration the drop and the

gradient specified above, must include a series of turns designed to allow

the competitors to combine speed with neat execution and precision of

turns.

802.1.3 The Slalom should permit the rapid completion of all turns. The course

should not require acrobatics incompatible with normal ski technique. It

should be a technically clever composition of figures suited to the terrain,

linked by single and multiple gates, allowing a fluent run, but testing the

widest variety of ski technique, including changes of direction with very

different radii. Gates should never be set only down the fall-line, but so

that some full turns are required, interspersed with traverses.

 

 

Giant Slalom:

 

903.1.2 The skilful use of the ground when setting a Giant Slalom is, in most

cases, even more important than for a Slalom, since combinations play a

less important role owing to the prescribed width of the gates and the

greater distances between them. It is therefore better to set mainly single

gates, while exploiting the ground to the utmost. Combinations can be set,

but mainly on uninteresting terrain.

903.1.3 A Giant Slalom consists of a variety of long, medium and small turns. The

competitor should be free to choose his own line between the gates. The

full width of a hill should be used wherever possible.

post #6 of 17

Whiteroom: GS skis currently are running a 27m turn radius, up from 25m which is up from 21m... longer faster turns.

 

Could anyone explain why this trend continues? When I watch WC GS races I see many turns that are so tight that racers simply do a gross re-direction above the gates. With 27m radii, all tight turns will be skidded to some extent. Is this done to make racing safer?

post #7 of 17

To reduce injuries. 

 

It has been proven that the more extreme the sidecut, the  more stress is put on joints. This fact is exacerbated at the kinds of speeds at which racers compete. After experiencing an extraordinary number of knee injuries among racers in recent years, FIS increased the sidecut requirements in the hope of reducing injuries. 


Edited by goblue - 2/18/2009 at 10:21 pm
post #8 of 17

Thanks goblue, this is what I heard. I suppose a shaped ski will carve hard and skid poorly, so at high speeds any skidding or straightlining can be dangerous.

 

So much for instructors telling us that it is much safer to carve than skid your turns.  Just kidding.

post #9 of 17

We need the dimension parameters from the rulebook posted to answer the question.

 

When will they race on fat skis? They're much safer! Plus you don't have to wax them, or sharpen the edges. Oh...you want to go fast around the turn?  Ok, well they're still safer!....  See everything about fat skis is better. Gosh....racers....stuck in the old ways!!.

post #10 of 17
Quote:
Originally Posted by jafergo View Post

 

I am not a theory guy, but can someone help me put in writing the general definition for GL ans SL truns? I need this for some school boys that are going to ski next week.

 

I kinda have an idea of what people mean by that but since I haven't heard this term in Europe so often I don't want to give the wrong information to the kids

 

We want to give them some general theory before they hit the slopes.

 

Thanks

 

Hello Jafergo and welcome.

As some has pointed out, if the kids are beginners (or never-ever) then, it's important to them to understand the basics of skiing, at that stage, to know what constitutes a GS or an SL type of turn is premature.If any of them has ever attended ski school, depending on the country, and progressed to at least intermediate level, instructors may have started to introduce how to ski those type of turns, using obviously, different names (as an example, a wedeln could be associated, in past times, to SL, while a Christy, to GS, this is a gross generalization on my part and done just for the sake of the present discussion)

post #11 of 17

No, its not that going straight or skidding in a super-sidecut ski is more dangerous.   The sidecut tends to lock the ski into the arc of the turn, putting more  rotational force on the knees during the turn, and when changing edges/directions.  Hence, an epidemic of ACL and related injuries.

 

 

post #12 of 17

goblue: The sidecut tends to lock the ski into the arc of the turn, putting more  rotational force on the knees during the turn, and when changing edges/directions.

 

But that makes no sense at all. There is no rotational force on the knee when you are locked in a carve, unless you try to pivot/skid, in which case it is the resistance to skidding that creates problems.

post #13 of 17
Quote:
Originally Posted by TomB View Post

 

But that makes no sense at all. There is no rotational force on the knee when you are locked in a carve, unless you try to pivot/skid, in which case it is the resistance to skidding that creates problems.

Yes, there is. And, the tighter the turn, the more rotational force that is being applied,

 

Your body wants to travel in a straight line. Whenever you turn, and throughout the course of any turn, the ski is preventing you from traveling in a straight line.  That puts  rotational force on the knees. The tighter the turn, the greater the force.  The only time you don't have rotational force on the knees is when you are going straight.
 

post #14 of 17

I think the most important thing you need to understand, jafergo, is that slalom and giant slalom turns are not the same as short radius and long radius turns, although most people incorrectly refer to SR and LR turns as being SL and GS turns (I see it all the time on this board).

 

For the purposes of your students, you shouldn't be talking to them about racing turns.  The technique and equipment used in skiing slalom and giant slalom are designed to maximize speed during directional changes, or more correctly to lose as little speed as possible (this is what ski coaches teach).  Recreational short and long radius turns are designed to control speed and give a recreational skier the appropriate tools needed to navigate a variety of terrain, safely and in control (this is what ski instructors teach).

 

Basically, just because a turn has a short radius, it doesn't mean it's a slalom turn, and a long radius turn doesn't mean it's a giant slalom turn.  This video shows a group of past world cup winners free skiing, but the difference between their long radius turns versus a recreational skier is that their turns are designed to carry as much speed as possible through the turn, not control speed.  The technical explanation of how this is achieved isn't important to your pupils.

 

post #15 of 17

goblue: The only time you don't have rotational force on the knees is when you are going straight.
 

I think you need to practice your turns.  I tip my ski, my body follows. The knees have no rotational force on them (other than the minor rotational force created by the hip socket, which is negligible).

post #16 of 17
Quote:
Originally Posted by TomB View Post

 

goblue: The sidecut tends to lock the ski into the arc of the turn, putting more  rotational force on the knees during the turn, and when changing edges/directions.

 

But that makes no sense at all. There is no rotational force on the knee when you are locked in a carve, unless you try to pivot/skid, in which case it is the resistance to skidding that creates problems.

 

The problem with a higher side cut is that they can get locked into too tight of a turn at speed for the body to handle, and can literally rip the knees apart and send the racer flying.  I've nearly done this on my slalom skis before (moderate speed, carving into a roller which helped to bend the skis much more than my legs were able to alone) and the grip and rebound were enough to send me flying over the skis (didn't injure anything, fortunately).  In a GS race, the risk is magnified because the speeds are faster and the skis are grippier.

 

In normal GS turns a short sidecut ski isn't going to injure anyone, but when it digs in unexpectedly and changes direction rapidly the force is there to cause serious injury. (think slalom turn at GS speed)

post #17 of 17

Good explanation exracer. This discussion is getting a little off track but that should answer the original question.  

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