quadratic sidecut?

G

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#2 · Feb 5, 2008

I have no idea what that means either bro. :laugh:

 

sedition

2,615 posts · Joined 2007

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#3 · Feb 5, 2008

cite source/context where you saw the terms used? It sound's pretty...well, "quadratic!"

 

Nivek

10,919 posts · Joined 2008

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#6 · Feb 5, 2008

quadratic means they use 4 different geometric equations to govern their sidecut radii. its a progressive sidecut meaning the harder you turn, the harder your board will turn. you will normally only find these kinds of sidecuts on freeride boards. if you sketch a landing in the park with one of these, your board can kinda get away from you, which is why park boards are usually a single, maybe 2, sidecut equations.

 

G

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#7 · Feb 5, 2008

Ok from what I have read, the quadratic sidecut basically means that the board is cut into three seperate radial cuts as opposed to a single radial cut. This is suppose to give the board more contact points (specifically around the feet)and give the board uninterupted contact with the snow. In other words, the quadratic sidecut has three seperate curves that form the sidecut vs. a single continuous flowing sidecut. Salomon calls this "Equalizer technology" and it seems that every company that uses this type of sidecut has there own name for it and a little bit of a design twist to dodge patents. The Burton boards with PDE edges also use this sidecut.

You can also check out PDE technology at Burton.com


SALOMON SNOWBOARD : Technologies Snowboards Gear, Tech Snowboard Salomon, Technology EQUALISER

 

G

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#8 · Aug 19, 2009

I know this post is old, but maybe someone will read it. A quadratic sidecut uses 3 or more radii instead of a continuous radial or elliptical sidecut. The radii of the sidecut is shallower at the ends, and deeper in the middle. The shallower radius at the ends promote easy turn initiation and a faster exit at the tail. The deeper radius in the middle allows quicker turns with more bite the more the board is put on edge. The shape also conforms with the boards natural flex.

This is not to be confused with a progressive sidecut which has deeper radii at the nose and waist with shallower radius at the tail allowing for a faster exit but promoting a directional or semi-directional ride. The quadratic can be ridden reg or switch. Different brands call the quadratic sidecut different names like 3D or whatever, so it's sometimes hard to know what the hell they're talking about.

A(x squared) + Bx+C=0 where x is a variable, A and B and C are constants, and A does not equal 0. The shape is derived from the quadratic equation although there are different quadratic equations.

 

G

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#10 · Aug 20, 2009 (Edited)

Got some intelligence here. Yeah, you're right. And I didn't say the elliptical was continuous, just radial. There would definitely be an infinite number of radii. I think what the manufacturers mean by 3 or 4 radii is that they're looking for a specific radius in a specific spot. This also confused me with being different from the tri radial, which is probably 3 radii contected by a tangent line, which would be different than quadratic.

From what I've read, I'm almost positive the tri radial and quadratic are different. The quadratic and elliptical should be different in that the change in radius in an elliptical sidecut is much more gradual, allowing you to make those long smooth carves.

As I said before, there are a lot of quadratic equations for making different curves, and I'll admit I'm no mathematician. If you look up Palmer Project, they use Klothoid (really clothoid) sidecut derived from the cornu spiral which is like quadratic but in reverse. So, like you said, it would be comparable to an elliptical sidecut. Anyhow, they show how different spots have larger or smaller circles. They got the idea from Kessler, who is a snowboard geometry genius.

 

BoardTheSnow73

165 posts · Joined 2009

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#11 · Aug 20, 2009 (Edited)

Clothoid = parametric equations = yukky

What I said earlier about Eliptical sidecuts was not 100% accurate. You actually want the sidecut to be an ellipse (when viewed perpendicular to the board) when the board is bent longitudinally during a carve. So when the board is unweighted, and the longitudinal bend is gone, the Ellipse is "unrolled" and becomes some form of Sinusoid. I'll bet this is what those folks at Palmer are up to. There are a bunch of sin and cosin functions in the derivation of a clothoid.

 

G

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#12 · Aug 21, 2009

Not sure, I've just always figured the elliptical sidecut was an ellipsis weighted. I know that when pressure is applied during a carve the board de-cambers even more into sorta a rocker shape allowing the board to conform to the shape of the carve. So I guess it could be so.

I don't know why Palmer uses a clothoid sidecut. They say its supposed to conserve energy (the obvious example being a roller coaster loop). But the sidecut doesn't start gradual like a roller coaster loop. Anyways, it's definitely math I don't know. That's why the manufacturers have engineers I guess.

I wonder if they use some kind of computational fluid dynamics in CAD to figure out how a shape is going to react in the snow. Or if they just keep making prototypes with tweaks until it's right.