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Anyone know how to find the sidecut radius?


jojogreen

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After looking on the Catek website, all Kesslers are made with a multi-radius sidecut. "According to Hansjürg Kessler, the most important component of the boards' success is the KST shape – an advanced, multi-radius sidecut,".

this means that finding the sidecut is even harder than plugging numbers into the calculator because of the multi-radius sidecut.

Don't get me wrong, the calculator is awesome and ingenious, but I am just warning kessler owners that the sidecut is different than the answer on the calculator because of Hansjurg's design.

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jojogreen,

I think that if you look into this a little more, you will find that very few manufacturers use radial sidecuts on their boards. They run the gamut of multiple blended radii to higher order math functions and some non-mathematically based splines. Most of the manufacturers advertise an "equivalent sidecut radius" just to give an idea. This, as you state, means you need to take results from any geometrical calculation with a grain of salt, not just with Kesslers, but just about any board.

The "new school" shapes have thrown this an even more extreme curveball based on how the shape of the sidecut changes over the length (without even getting into taper profile and (de)camber). Knowing the approximate sidecut of a board can sometimes be helpful, but most likely will not tell you enough about the ride characteristics of the board in a vacuum

Don't think I have much of a point with this post, other than extending your comment beyond just kessler and to a larger portion of the market.

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~tb + 1. And I'd like to point out the irony here... snowboard manufacturers have been advertising sidecut radius (or equivalent) since about 1990, iirc. It wasn't until relatively recently that sidecut radius would be published by ski companies, printed on skis, or mentioned in ski magazine reviews. At the same time, snowboard racers have gone back to simply referring to a sidecut as "PGS" or "SL", and the numbers are back to being secret. Ha.

It still doesn't make sense to me. :)

But I can't wait to try one.

Well when you consider that a traditional radial sidecut ceases to be radial when it is up on edge, the door is open to lots of different shapes.

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I can imagine benefits to sidecuts that are not radial but that are symmetrical from tip to tail. What I can't get my head around are sidecuts that curve tighter at the tip and less at the tail.

Call me old school, but when I carve, I like to turn the tip and the tail at the same rate. :)

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I can imagine benefits to sidecuts that are not radial but that are symmetrical from tip to tail. What I can't get my head around are sidecuts that curve tighter at the tip and less at the tail.

Call me old school, but when I carve, I like to turn the tip and the tail at the same rate. :)

I used to think that until I rode one. I think part of the idea is that towards the end of the turn, your weight is typically shifted more to the tail. So a tighter sidecut on the front half of the board compensates for the fact that there's less pressure up there.

However I think for getting tight turns done on narrow steeps, a board with a constant or front-to-back back symmetrical sidecut would be better because it wants to finish the turns more aggressively. That was the first thing I noticed when stepping off the NSR back onto my Schtubby - even though it has a relatively long sidecut for a 171 (14.2m), it really wanted to continue coming around in the bottom half of each turn. The NSR allowed me to make a normal top half of the turn and then "surf out" the bottom half. I think this is what our bodies and minds naturally want to do when making bigger turns, and that this sidecut configuration works better for that.

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I used to think that until I rode one.

The NSR allowed me to make a normal top half of the turn and then "surf out" the bottom half. I think this is what our bodies and minds naturally want to do when making bigger turns, and that this sidecut configuration works better for that.

Control shape and direction at the top of the turn, and then build speed into the next!!! Of course all it takes is a little weight tranfer toward the tip or tail to alter the turn shape again! More rider control then ever befor!

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That calculator is interesting to play with, (thanks Nate) I found suprising similarities over 5 boards that vary a lot in ride feel & over all length.

173 Identity & 183 Grocer ride feel is very similar (powder boards) at 9.6r & 12.3r.

165 Nidecker & 178 Oxygen ride very different (freeride boards) at 10.1r & 10.6r.

This has been helpful for dialing in what I want in a custom; something in the range of 190, 160 effective, 23 waist, 13/14 progressive radius, 7-8 out of 10 flex, and twin powder tips.:biggthump

Similar to Steve P's Diablo but less of a 210 beast.:eek:

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Control shape and direction at the top of the turn, and then build speed into the next!!! Of course all it takes is a little weight tranfer toward the tip or tail to alter the turn shape again! More rider control then ever befor!

Agreed.

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~tb + 1. And I'd like to point out the irony here... snowboard manufacturers have been advertising sidecut radius (or equivalent) since about 1990, iirc. It wasn't until relatively recently that sidecut radius would be published by ski companies, printed on skis, or mentioned in ski magazine reviews. At the same time, snowboard racers have gone back to simply referring to a sidecut as "PGS" or "SL", and the numbers are back to being secret. Ha.

Well when you consider that a traditional radial sidecut ceases to be radial when it is up on edge, the door is open to lots of different shapes.

my race (ski) boards all had the sidecut radius printed on the topskin since the late 90's...at least 10 years ago. But it's as if sidecut radius is the only factor in the way a ski or board turns, it's *a* factor but not *the only* factor. It might not even be *the most important* factor. It wasn't all that long ago that rossi made both their 7S and 7G with the same sidecut <gasp!>. Or maybe it was that long ago..... LOL :) I agree, sidecut radius is overrated in recreational skis, no doubt.

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I used to think that until I rode one. I think part of the idea is that towards the end of the turn, your weight is typically shifted more to the tail. So a tighter sidecut on the front half of the board compensates for the fact that there's less pressure up there.

However I think for getting tight turns done on narrow steeps, a board with a constant or front-to-back back symmetrical sidecut would be better because it wants to finish the turns more aggressively. That was the first thing I noticed when stepping off the NSR back onto my Schtubby - even though it has a relatively long sidecut for a 171 (14.2m), it really wanted to continue coming around in the bottom half of each turn. The NSR allowed me to make a normal top half of the turn and then "surf out" the bottom half. I think this is what our bodies and minds naturally want to do when making bigger turns, and that this sidecut configuration works better for that.

So how does that configure into binding placement? I shift my bindings forward and back on different boards for different types of riding and snow conditions.

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Moving the bindings back will always help keep the nose up in deep snow; that said the difference in the feel of the board from a stance shift towards the tail will be greater on shapes with more taper or progressive/multi-radial side cuts.

My 173 Identity & the 169 Atomic Radon are very similar in shape & flex.

I found much less technique adjustment was required when increasing the setback on the Identity with a symmetrical elliptic sidecut, and I noticed a much greater difference with the same amount of setback on the tapered progressive tri-radial sidecut of the Atomic.

Hope that made sense. I always play with stance position on various boards to find the "sweet spot".

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  • 1 year later...
http://www.natew.com/

Click the snowboard link, and you're there. It's working again.

NateW,

I know this is an old thread but would like to measure SCR of my old beast. The link you've provided is not working again. Would you share your formula here if you are not going to bring life to the 'SideCutRadio-Matic'?

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  • 3 weeks later...
r = d/2 + e2/8d

d = sidecut depth (((nose width + tail width)/4) - (waist width/2))

e = effective edge length (widest point to widest point)

Jack, I'm not sure where and how you have calculated "d" or "e" but be careful as to how you apply those calculations to find "r". The formula for "r" is correct but I think you may be a little off with both "d" and "e". You are calculating "d" by taking the average of the nose and tail width then subtracting that measurement from the waist width, then taking half of that difference. That length may not fall on the circle in which you are trying to find the radius. There is another way you can measure this without averaging anything. Simply mearsure a length along the sidecut between the return radii of both the nose and tail. This is "e". Then measure the greatest distance from the edge of your board to line "e". This measurement is "d". It must be done at the midpoint of "e". This can easily be done by using a known lengthed straight edge for "e" then measuring "d" in the middle of "e". You can then use r = d/2 + e2/8d and it will be true. If you need to see the geometric interpretation of this I will eventually send it to you.

Good Luck

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Now use Pythagorean’s Theorem and solve for “r”. (r-d)^2+ (1/2 e)^2=r^2. Solving for r,

r= (e^2+ 4 d^2)/(8 d). If one uses the method that Jack describes for finding "d" and "e" you will more than likely get a radius a little bit bigger than what the true radius is. Depending on the nose and tail width it could be pretty far off.

circular side cut 1.pdf

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