Sidecuts, Waist Widths and Tip Flex...Oh My! (Part Deux)

So last time we figured out that narrow skis float poorly but initiate turns quicker than their portly counterparts. The width of the ski affects the performance into and out of the turn, but how about what that turn looks like in between?


This is the realm of the sidecut. Back in the early 80's skis underwent a radical change from being long, straight, hard to turn planks into the more user friendly and performance oriented designs of today. Correct me if I'm wrong, but this revolution started with the Elan Carver, marketed as the first true "parabolic" ski. Anyone who has spent time on a pair of 210s from the 60's can tell you that shaping the side of the ski makes it much easier to handle than having two parallel edges. I could go into a lengthy discussion of how a sidecut works, but thats for another article.


Instead, I'm going to get right into how a sidecut shape makes a ski handle. Most sidecuts are basically segments of a huge circle. The radius of the circle is the sidecut radius and this circle is the shape of the turn that you will get if you simply tip the ski on edge and go with it. The shorter the sidecut radius, the tighter the natural turn of the ski will be. Pretty simple. Bending the ski harder will tighten that circle by a predictable amount.


But what if you want to turn really hard? You can either push on the ski harder or go with a ski that has a "progressive" or "quadratic" sidecut. This time the sidecut is not a section of a circle, but a section of a parabola or a smaller radius circle cut into a larger radius one (depending on the company). If you remember your calculus (that would make one of us), a parabola's radius is smaller the closer you get to it's center so a ski with a progressive sidecut will turn much much sharper with a comparatively smaller flex put into it.


Lastly, where a sidecut is centered on the ski makes a difference depending on what you want to do with it. Most manufacturers put the deepest sidecut where the foot is, which for all but park skis is about 4/6th of the way back from the tip. Mounting a pair of these skis centered on the ski but not the sidecut won't help any switch riding you want to do and mounting a ski with a symmetric sidecut in a traditional alpine manner will reduce it's performance.

So for those of you who slept through the lecture here's the cliff notes: A deep sidecut will make you turn harder, a progressive sidecut gets deeper the farther you push into it, and a symmetric sidecut is good for all the switch, fakie, gnar gnar you can throw at it. Believe it or not there's alot of math that goes into making sidecuts on skis work they way you do (stay in school, ski bums) and that technology is all about making you arc some sweet tracks.

So while you're maching those killer turns, take a look down at your ski. Its moving and its bent...this is flex and the topic for our next article.

Excuse me while I integrate my natural log,

Geoff
www.alpine-sports.com