Body Weight, Longitudinal Flex & Performance

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Body Weight, Longitudinal Flex & Performance

Postby rcrobar » Thursday 28 August 2003, 16:11

Hello to the Extreme Carving Team

These questions are inspired by years of buying stock boards where one flex was made to fit most rider sizes.


The Medium settings chart(s) in the board selection guide(s) has a 12 Kg (25 Pound) low to high range.

What kind of ride differences can a 74 Kg rider and an 82 Kg rider expect when both riding the same 175 Medium flex? (Both weights fit into the medium range.)

Jacques, could you compare/describe how the 175 hard flex and the 175 medium flex performed-behaved when testing the two boards at your 82 Kg body weight.

How much do variables like leg strength, level of rider aggression/ability, boots-bindings being used and personal preference affect way the board selection chart is designed?


PS - Can’t wait to see the next Extremecarving movie!

Thanks
Rob
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Postby rilliet » Friday 29 August 2003, 11:37

Hi Rob,

In the ideal configuration, everyone should have his own board specification.
Except for pro riders, this is impossible to realise because the boards characteristics depend on a lot the riders characteristics: weight, size, boot size, riding level, use of the board, other equipment (boots, bindings) and personal wishes. Furthermore, different snow conditions will change the board behaviour.
Such a custom board should be develloped with the rider. This means that several boards would be built and that the rider is able to accurately communicate the feelings he gets when riding a board.

The SWOARD system is an approximation of this ideal situation. In your first example, both riders will have different feelings on the same board (175 medium).

The 74 kg guy will feel the board quite hard on icy snow, but will be able to reach further limits when the snow is softer.
The 82 kg guy will have a better grip on ice, but will have to be more careful on soft snow.

So all this is a compromise and the goal is to be sure that everyone gets a board that fits him.

In your second example, I will describe the differences I feel on the three stiffnesses of the 175, in soft and icy snow.

Soft snow:
175 hard: this board is crazy! I can push without limit and get huge extremecarving Gs. I have to jump in the laid turns to make the board bend. The sensation is great, but my legs are burning.
175 medium: the board is less fatiguing to use but I can't push as hard I could with the harder one.
175 soft: It's like riding on eggs. I must be carefull not to push too much otherwise the board bends too much during the turns and makes me loose my balance. Very easy to manoeuver but not as fun at all as the two harder ones.

Icy snow:
175 hard: bad grip. It's difficult to make the edge carve in the snow. Because of this, the board tends to chatter a little bit during extremecarved turnes.
175 medium: excellent grip. This board is just perfect for me, especially with the BOMBER bindings that helps the board to bend as a perfect circle arc.
175 soft: excellent grip too, but much more sensitive to my balance errors and to the piste unevenesses. In these situations, the board tends to bend too much in front of the front foot making me loose my balance. I can't ride as fast as with the medium one.

Conclusion: if the snow was always soft, the boards selection guide would advise a slightly harder board. In opposite, if the snow was always icy, a slightly softer board would be advised.
But as we have to ride any kind of snow, we have to choose a board that still works well in any situation.

Note that the ATC Matrix helps to reduce these differences of behaviours and makes the board ride in a more constant way on different kinds of snow.

How much do variables like leg strength, level of rider aggression/ability, boots-bindings being used and personal preference affect way the board selection chart is designed?

Usually, a strong and agressive rider wants a stiffer board because he says he can push to compensate his weight. In extremecarving, this doesn't really work because the direction of the rider strength is nearly perpendicular to the gravity force. If you push too much in a laid turn, you create a force that tends to make the board slide away instead grip. This is the reason of the push-pull technique: to put the minimum strenth that makes the edge slide.
In a normal ride, all this doesn't happen, because the rider force is added to the gravity and helps the edge to grip.

This is why a good (extremecarving) rider will not choose a quite harder board than a beginner. The boardstiffness is really directly related to the riders weight, only very few to the legs strength.

Boots have a great influence on the rider style but not a lot on the board stiffness.
Bindings have more influence. The base plate softness and size is bound to the overall stiffness feeling. The bigger and harder it is, the stiffer the board will be.

I hope you have here enough information to keep up your personnal extremecarving quest. :wink:

Jacques
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Board stiffness and snow conditions

Postby harald » Monday 1 September 2003, 12:30

Hi Jacques,
Thanks for your very instructive comments on board stiffness and snow conditions. Still, I have some problems with really understanding how it works. From alpine skiing I have learnt and experienced that soft snow means soft skis (and boots) and hard/icy conditions means a harder ski. Hard skis will dig and "push" snow when it's soft, while a soft ski will skid and loose its grip when it is icy. I know that torsional stiffness decides most of the grip and that modern skis can be soft in the length direction and still be very stiff torsional (as my racing SL and GS) skis. Still they are difficult to handle when the snow is soft.
For carving boards I thought the same rules of thumb applied. Before I bought a SWOARD, I used a F2 Speedster GTS in soft conditions where it worked quite well. On ice, however, the Speedster was more difficult to handle as it scattered and lost grip. I also have a F2 Speedster RS, that I found worked best when it was hard. In softer snow the tip dig into the snow with forward falls as a result.
How come that it is the opposite with the Swoard, that is hard board for soft snow and vice versa? If you could explain this to me, I would be very grateful. (Maybe, we have different opinions of what soft snow means?).
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Postby audacium » Monday 1 September 2003, 16:50

Hi Harald,


I think it has to with the one fact Jacques already mentioned somewhere in his post and with the ATC matric that helps bending the board always to the "ideal" arc in curves:

In EC the forces that guide the board are almost perpendicular to gravity force.
On icy snow you need the whole edge in the snow to have grip. If you put the board perpendicular to the snow it will not touch the snow in the middle because of the smaller width in the middle (Taillierung in english?) So you must really bend the board in EC carves to have the whole edge in the snow. And bending is easier with a soft EC board.
Why the difference to a "normal" board and normal riding style (no EC): Here your edge always remains in the snow because one does not really carve low. The board remains almost horizontal, gravity and centrifugal force have almost the same direction, so the edge remains even in curves in the snow.
In soft snow you can ride the hard EC board because the ATC matrix helps really distributing all centrifugal forces over the whole edge so the board will not skid as a "normal" board would. The soft EC board in soft snow is already too soft because it now allows too much pressure in curves compared to a hard EC board - given its softness.
A "normal" board in soft snow has to be soft because otherwise one does not manage to bend it - the soft snow does not offer enough grip for a "normal" hard board to bend. EC boards do not need this because of the ATC matrix.
So again, I think one of the main reasons is the different riding style in EC and especially the ATC matric which distributes forces right along the whole edge, independently of the board stiffness. "Normal" board need to do this via their stiffness.

Jacques - did I get that right? Curious whether I resolved the puzzle or whether Harald has a point!

Greetings, Eduard.
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Postby rilliet » Thursday 4 September 2003, 6:52

Hi Harald and Eduard,

First, I have to say that I never rode a F2 board, so I can't compare with the Swoard. Second, for the last 20 years, I've been skiing 3 times only, onces with carving skis. So, again I can't seriously discuss about skiing technique.

In soft snow (not too light, sothat it can handle the edge pressure) the edge goes easily in the snow. The board digs a quite deep path. This means that the edge gets grip and pressure all along its length. This will make the board bend easily and makes its stiffness feeling softer (this ia why a harder board is needed). But the condition sothat it works is that the edge is correctly guided by the nose.

Lots of noses are bad designed and make the boards dive into the snow when carving. In fact, the nose, the flex and the torsion are all bounded together allowing the board to work well or not.

Eduard is right: the ATC Matrix is crucial in the Swoard behaviour, but it couldn't work correctly without a good nose shape and flex pattern.

On ice, the edge needs much more pressure to dig its path and grip. With a given force, the only solution to get more pressure is to shorten the edge part that will grip. because its tips are not pushing too hard, the edge of a softer board will grip on a shorter length: the part that is under the feet. This allows more pressure and a better grip. The edge works like ice skates, that are very short, but grip perfectly on ice.

Again, in this configuration, the nose shape and the torsion and flex patterns decide if a board works well or not.

Jacques
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Board stiffness and snow conditions

Postby harald » Thursday 4 September 2003, 12:59

Hi Eduard and Jacques,
Thanks to both of you for your very instructive and clear answers. The important thing is to keep the whole edge in contact with the snow. You both gave me a good explanation how this works under different snow conditions, board angles, and board stiffnesses. Even if it still is summer, I am looking forward to go out on the slopes in order to practice the linked EC turns.
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