Ski camber vs. rollerski flex

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skiffrace
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Ski camber vs. rollerski flex

Postby skiffrace » Sat Jan 14, 2017 2:52 am

A classic x-country ski has a camber in the middle. When the ski is unloaded, it glides on the front and back sections that are specially designed for low gliding resistance, and sometimes also waxed.
During the kick phase the middle, cambered section is pushed into the contact with the snow, so the klister, skin or fishscale arrest the backward slide of the ski.
Or something like that, right....?
Now, some (usually the better) rollerskis are advertised as having "flex" built-in.
Since rollerski always provides perfect kick due to ratcheted wheel, its flex is not useful like that of the ski.
I assume the main benefit of the rollersk flex would be a more comfortable ride on rough surfaces.
I also assume that during the kick phase the rollerski flexes and absorbs some of the power of the kick.
I wonder is this is a desirable or undesirable feature?
If the ski does not release the energy (flexes back) until the kick is completed, then the flex would be wasted energy. But perhaps it is returned still while you kick, and adds more power near the end of the kick?
Or is there more to it?

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Magnus Johansson
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Re: Ski camber vs. rollerski flex

Postby Magnus Johansson » Sat Jan 14, 2017 4:29 am

skiffrace wrote:I assume the main benefit of the rollersk flex would be a more comfortable ride on rough surfaces.
I also assume that during the kick phase the rollerski flexes and absorbs some of the power of the kick.
I wonder is this is a desirable or undesirable feature?
If the ski does not release the energy (flexes back) until the kick is completed, then the flex would be wasted energy. But perhaps it is returned still while you kick, and adds more power near the end of the kick?
Or is there more to it?

Very interesting questions, Tom. I prefer flex in a rollerski, mainly because of the better comfort it gives, but some elite skiers like Marcus Hellner and Eirik Brandsdal prefer a rigid rollerski because they think that it feels more like a ski on snow. This has likely something to do with the power return.

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Neuro
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Re: Ski camber vs. rollerski flex

Postby Neuro » Sat Jan 14, 2017 8:34 am

To be similar to snow when skating I guess there should be the opposite of bounce-back and more like a washout, or whatever the correct term is. I guess a well measured flexing rollerski might do that in that it flexes right at push-off.


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