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# '99 Volkl P40 F1 -- Turn Radius?? - Page 2

Just about any ski can be made to go in a straight line (ie, infinite radius), and just about any ski can be used to execute on-the-ground 360's (ie, zero radius turns), so in an absurdly strict sense, of course no one will have "an idea of the turn radius" of any ski.

However, its clear that this is not what Jluecht was trying to get at. He was being casual in his language. I strongly suspect that what he meant (in more precise language) was: "Does anyone know over what range of turn radii will it be relatively easy to get these skis to execute carved turns?".

The answer to this was discussed in one of my earlier posts and DOES indeed depend on the geometric sidecut radius. Specifically, without using either extreme or very shallow edge angles (on the flats), you can usually get most skis to carve in a range of turn radii from around 40% of the sidecut radius up to about 90% of the sidecut radius. That's my "idea of the turn radius on these skis". It's a pretty broad range, but that's what the phrase, "an idea of", means to me.

Tom / PM
PM

Do your calculation on a pair of straight skis watch an old film of someone like Alberto Tomba skiing slaalom, and you will have witnessed the impossible.

In an attempt make their marketing more useful, I suspect many of the manufacturers do attempt to provide 'magic' figures for turn radii, so that it is not merely the sidecut radius, which as you have implied is probably a composite arc anyway.

The sidecut radius without info on the other factors tells you little more than the shovel/waist/tail dims already suggest, infact this is more useful as the width of the ski is also significant.

Would a mid fat and slaalom ski of equal s/c radii be expected to turn similarly?
Quote:
 Originally posted by daslider:...I suspect many of the manufacturers do attempt to provide 'magic' figures for turn radii, so that it is not merely the sidecut radius...
If you are claiming that the radius number stated by some of the mfgrs is anything other than the simple sidecut radius, I have never seen this done. In setting up my sidecut radius calculator, I looked at data on hundreds of skis, and when a radius was given, the number was always extremely close to what the simple geometric formula predicted for the particular ski.

OTOH, if you are claiming that some mfgrs incorrectly label the sidecut radius as the "turn radius", I believe I did see instances of this. I regard this in the same way as when this error periodically arises on Epic and in other discussions of skiing. Most people simply haven't thought about this issue, don't even know that two different terms exist, and certainly can't articulate the difference between them, even when you point out the two similar sounding terms.

I guarantee you that the geeks in the back rooms of Atomic, Volkl, k2, etc know perfectly well what the difference between the terms is, but once their less technical marketing and advertising people get involved, precision of terminology often goes out the door.

To reiterate what I said above, whenever a radius number for a ski is given by the mfgr, in my experience, it is always the simple geometric sidecut radius, no matter what name they might have given it.

Quote:
 ...The sidecut radius without info on the other factors tells you little more than the shovel/waist/tail dims already suggest, infact this is more useful as the width of the ski is also significant. Would a mid fat and slaalom ski of equal s/c radii be expected to turn similarly?
Of course, no one would expect them to turn similarly. This is obvious. We have discussed this numerous times before in this thread.

Width is just one more item in that long list of factors I gave (my post time-stamped April 21, 2004 08:42 AM) which will cause two skis having the same sidecut radius to turn differently. I didn't explicitly point out "width" as a factor, but that's why I put an "etc." at the end of the list.

Tom / PM

'I am curious if anyone has an idea of the turn radius on these skis'

PM later says:

'daSlider - For exactly the reasons you mention, my program only calculates the geometric sidecut radius (ie, the number printed on some skis), not the turn radius. No one *ever* attempts to calculate the turn radius'

so the answer to the initial question is NO, rather as I suspected.
Ok, you caught me... i should have said specificlly the 'sidecut radius' -- my bad, i won't argue over that.

I already knew the waist, tip, tail dim's, so i was looking for the geometric radius of the ski. I ended up buying new Fischer Worldcup SL's with a 13m cut, 115mm,65mm,101mm and a pair of World Cup GS with a >21m, 105mm,65mm,89.5mm. I merely wanted more info to compare the skis to determine if the shapes of the new Fischers were radically different than my P40s of only a few years old. It seems the SL's are significantly different, though the GS's aren't since FIS regulations have placed restrictions on them.

Jason
Jluecht

'i should have said specificlly the 'sidecut radius'

I don't think this is really the point and certainly not one worth discussing. This radius is such an arbitrary figure that I am unconvinced by any of the discussion so far that it is worth the candle of calculating such a figure when you already have the basic sidecut widths.

Until a ski can ski on its own the notion of a natural radius is hokum. Has anyone yet looked at Tomba's natural turn radius? It's a joke.
22 M. I have a pair of the "green" (some are red), however, the GS design allows for considerable variation of the normal radius. Nice ski for cruising (or club racing).
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