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Ski side cut and given turn radius question

post #1 of 11
Thread Starter 
I have been looking at some of the information given by ski manufactures about the specifications for their skiis. It looks like different skiis with identical tip-waist-tail widths can have different turn radia (sp). Sorry I do not have any specific examples at this time. Maybe, I am confused on this issue, but if not, can anyone help me understand this seeming contridiction?

post #2 of 11
Thread Starter 
I just read some more of the threads in this forum. I see this issue has been addressed previously. It looks like I will be able to come up with an answer to my question on my own if I put in a little work. Sorry about premature post. I would welcome a short (polite) response from anyone who would like. I really did not intend to rehash a previous thread.
post #3 of 11
From what I understand, turning radius is determined not only by the sidecut, but also by the stiffness of the ski as well as the height of the sidewall (thickness) of the ski and the camber.

For example, two 175cm skis with the proportions 111-67-98 may have different turning radii (sp) because one is a foam core and one is a wood core. Also, ski "A" may have vertical dimensions of 5-15-5 mm thickness while "B" is 7-20-6. A third factor is the camber (not sure if this is the correct terminolgy) the skis have. If you put them on a table and measured the distance off the surface each ski is in the middle, they might be different.

post #4 of 11
Thread Starter 
Thanks Scott, that helps.
post #5 of 11
ski length also effects turn radia from ski to ski. So the same model ski (ex. 125/82/110) in a 177cm has a 17.8 meter radius the 184cm has a 19.2 meter radius, due to the change in length.

post #6 of 11
Sidecut radius is the radius of the hypothetical circle from which a given ski's sidecut was mathematically derived.

It has nothing to do with the flex of the ski, it's simply a mathematical computation involving the tip, waist, and tail measurementsand the distance between them.

This is why skis with the same tip/waist/tail dimensions can have different radii. The distance from tip to tail must be different.

Footnote: Most published radii are only approximations anyway. Many modern ski designs no longer use cirlular sidecuts. Elliptical and parabolic sidecuts are common, so computing a circular "radius" for these skis isn't exactly accurate.
post #7 of 11
There was a thread on this one or two weeks ago. I´m sure to have written about it then with some examples why the "nominal" and "real" radiuses differ.
Nominal = what´s written on the ski or in the catalog
Real = the precise radius calculated
They are both SKI radii
The TURN radius is different... cf. the threads
post #8 of 11
I'm confused. How can I tell if the turning radius specified in the catalogue from a ski manufacturer will be the same turning radius I get when I purchase a ski?

Ex. I like the 176cm Atomic GS 11. Am I getting a ski with a turning radius of greater than 21 m? What exactly am I getting when I try this ski? It's obvious Atomic isn't going to give me an accurate answer based on their claim that the GS 11 I will purchase is the same as Bode's GS skis.

Why don't all manufacturers give the dimensions and turning radius of each model/length so I can purchase the ski that best suits my turning radius?
post #9 of 11
Read troutman's post again.

The number isn't "turning radius," it's sidecut radius. It's depends on tip-waist-tail measurements and length (I suspect that "length" is the true answer to the original poster's question). Plus, there is some "play" in exactly where you measure the tip-waist-tail, and exactly how you calculate the radius from them, though the differences shouldn't be dramatic.

Think of the sidecut radius number as a single number that summarizes the relationship of the tip, waist, tail and length measurements.

It's useful to do a quick comparison of sidecuts, but there are tons of other variables that go into how a ski skis, and whether a ski is right for you (like flex in general; relative flex of tip and tail; waist width; torsional rigidity at various points; weight; etc. etc.) You'll never know exactly what you're getting when you try a ski, except by trying it.

Atomic is actually among the more forthcoming manufacturers in terms of specs. They're the only ones, I believe, who list the t-w-t dimensions for each size.

I don't think they claim that the GS 11 you purchase is the same as what Bode uses. It's not a secret that they have two different retail models of GS 11 (FIS-compliant and not) ... you can walk into a shop that has a race clientele and buy the FIS-compliant version if you are so inclined (and if they're not out of stock by now). Whether that is exactly the same as what Bode uses, well ... no. I don't think you'd want the exact same skis he uses, since you ski differently (I'll assume). Other World Cup racers don't even necessarily want the same skis as each other.

FWIW, Atomic specs the 176 cm GS11 as 103-65-93, for a sidecut radius of 19 m (I get slightly less, using an apparently slightly different calculation method).
post #10 of 11
Originally Posted by sjjohnston
Atomic is actually among the more forthcoming manufacturers in terms of specs. They're the only ones, I believe, who list the t-w-t dimensions for each size.
Atomic, Dynamic, Elan, Salomon, Volkl have the dimensions and radiuses for each ski length in their catalogs
Head doesn´t list them all in the catalog but has them in the manual
post #11 of 11

insert "... in an easy-to-find place on their website ..."

Although it's not that easy to find. Which is true of almost everything on the typical ski-industry website.
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