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 Post subject: Sidecut Radii?? (skis vs. snowboards)
PostPosted: Sat Sep 03, 2005 10:41 am 
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Why do snowboards have such short sidecut radii compared to skis? For most snowboards it's about 10 meters, even for the carving boards. In contrast, skis have a sidecut of around 20 m.

Could this have something to do with poorer edge performance on firm steep slopes? I think it does.

Does anyone manufacture snowboards with longer turn radii?

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PostPosted: Sat Sep 03, 2005 11:12 am 
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snowboards are twice as wide. ??

are the terms "sidecut" (snowboards) and "turn radius" (ski's) synonomous?

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PostPosted: Sat Sep 03, 2005 11:29 am 
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Well sidecut radius has to refer to the radius of the arc inscribed by the sidecut. I think the 'turn radius' term is used because ski sidecuts are not actually circular.

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PostPosted: Sat Sep 03, 2005 11:50 am 
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Ok so the BD Crossbow 163cm ski has a 114 mm tip and 83 mm waist, making for 31 mm / 2 = 15.5 mm of sidecut per edge.

The Voile Mtn Gun 161 cm splitboard has a 300 mm nose and 252 mm waist, making for 48 mm /2 = 24 mm of sidecut per edge.

Without even looking at the reported radii, it should be clear from these values that the the splitboard edge is more curved than the ski edge.

Radius for the ski is reported as 19 meters, for the snowboard 8.55 meters.

A ski with a sidecut of 48 mm total, or 24 mm per edge, would be considered horrible for skiing steeps. At least, as far as I know based on what I hear from skiers.

The width of the board doesn't really have anything to do with sidecut. Sidecut simply determines how much the ski or board must flex for the entire edge to engage. A shorter-radius sidecut (more curved) on a board means that your nose and tail bear more weight, while the edge directly under your body has much less purchase, unless the board is REALLY flexed.

I am really curious about how a 15 meter sidecut snowboard would perform on steeps...

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 Post subject:
PostPosted: Sat Sep 03, 2005 12:12 pm 
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skier perspective:

http://www.telemarktalk.com/phpBB/viewt ... 61&start=0

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PostPosted: Sat Sep 03, 2005 12:56 pm 
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Check this out:

Image

This is a comparison of a split decision 166 splitboard vs. a BD Crossbow 163 ski. The tips and tails are aligned. One can see that there is a dramatic difference in the depth of the sidecut in the center!

I am positive that a snowboard with a sidecut more like the ski would hold an edge better.

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PostPosted: Sat Sep 03, 2005 4:28 pm 
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The sidecut changes drastically when the ski/board is flexed by loading in a turn. Perhaps skis flex more with the (one) foot centered on them as opposed to a rider's (both) feet placed apart, and the actual turning radii, board vs. ski, are about the same for any given turn. A snowboard racer would have insight into this.

But there's a new sidecut in town, and it's scalloped:
http://www.lib-tech.com/tech/magneTract ... ction.html
I can't wait to try it.


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 Post subject:
PostPosted: Sat Sep 03, 2005 5:32 pm 
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In the ski world, more sidecut is a relatively new idea, brought about to make turning quicker and easier. But I would gladly give up some slaloming performance for the ability to keep myself from falling off the mountain.

Pretty much all of the skiers I know think less sidecut is better for steeps...

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 Post subject:
PostPosted: Sat Sep 03, 2005 5:48 pm 
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Matt wrote:
But there's a new sidecut in town, and it's scalloped:
http://www.lib-tech.com/tech/magneTract ... ction.html
I can't wait to try it.


What the hell? :o

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 Post subject: Skids, falline, evolution
PostPosted: Sat Sep 03, 2005 7:52 pm 
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Most skiers up until recently skidded all their turns. Sidecut, relativly speaking, is a new thing in skis. Even advanced skiiers are still running with their tips down the fall line the bulk of the time. Snowboards were designed to turn quickly, and with the advent of terrain parks, a 7m sidecut radius is failry common. On the otherhand, most slalom snowboards have sidecuts in the 9-10m range, while most GS boards are aprox 178-185cm with a sidecut radius of around 15m. Its rair to get a board over 19m in radius, and even then its usually a custom super g/ way open GS. Snowboard races are often won by who spends the most time carving, on edge. Seems to have changes a bit with tighter dual format racing though... Compaired to modern slalom skis, boards are fairly close, though GS skis seem to be closer to 20m sidecut radii (sp?). Again, I think that due, in part, to the tips being focused down hill more.

Now, in regard to edge grip, I think we really need to be concerned with sidecut depth, a point illustrated in the above pic. The shallower a sidecut, the less one needs to weight the board to get that edge to engage. A 155 board with a 6m disecut radius is going to grip (as far as egde %) better then a 170 with a 6m sidecut. I prefer mid/long boards w/ less sidecut depth for steeps, ie, aprox. 165-170 with aprox. a 10m sidecut radius (like the Donek Incline 164 I have w/ a 9.65m sidecut. Pretty huge by modern freeride standards.

That said, i still dig my 186 Coiler board with a 15m radius as my general feel good- great grip board. But I like to arc that thing across (and up) the fall line way more then most of my skiier buds.


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 Post subject:
PostPosted: Sat Sep 03, 2005 7:56 pm 
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Huevon - Oh, I agree that less sidecut is better in the steeps, just maybe not the kind of sidecut you're talking about, but really I don't know. My main point was that comparing a board's sidecut/radius to skis is useless.

Sidecut also has to be balanced with board length and stiffness against intended use. Long raceboards have long radii and they're very stiff so you have to really load them up to turn them and they're really only good for high-speed GS turns. But even these GS-type boards have gotten shorter and more sidecutty in recent years.



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 Post subject: Forgot one item...
PostPosted: Sun Sep 04, 2005 8:07 am 
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Skis have needed to get wider for the sidecut numbers to become "tighter". There is only so much that you can do with a very narrow ski, even with lifters for the binding. I think that on snowboards the sidecut is too tight, with numbers like the 161 mtn. gun at 8.55. I personally would like to see that one be up around 9.5 to 10 on the sidecut. It would be better on the steeps, and you could open 'er up on wider slopes and carve turns with more stability.

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 Post subject:
PostPosted: Tue Sep 06, 2005 8:49 am 
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I remember a conversation with Tom Burt and Jim Zellers about this subject during the split-fest. Basically they were in full agreement about narrower board, and larger radius, shallower sidecut boards. Case in point Tom's factory board has a Radius of 10.9m.

Personal experience for me is that yah, I like a mellow sidecut for steeps as well. My prefered steep/hardpack board is a Donek Incline, 168... 10.xm sidecut, 24.5 waist, stiffer than average... You get more effective edge per length, and more of it actually stays on the slope..

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