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Well, I think this article is what you get when someone without any technical knowledge tries to interpret biomechanical research. His video is a little better, but the article is terrible IHMO. He clearly doesn’t really understand ground reaction forces and moment arms (aka lever arms), though he’s absolutely right that wide skis that are great in powder are not good on hard pack.
Wide skis / snowboards are like your sailboard, they “plane” on the fluid (snow) that they’re in. Like your sailboard, they “carve” through powder by using the normal force (perpendicular to the bottom of the ski/board) to move you through an arc. Because it’s angled, and not pointing straight up against gravity, the snow/water is pushing in the direction of the center of your turn. So you turn. There is some flexing of the ski/board that assists, and the fin of a sailboard is also pulling up on the tail, adding to the turning force.
On hard snow, it’s more like a flexible ice skate, where the edge of the ski digs in, and the sidecut (curvature of the side of the ski) and the flexing of the ski make the edge form an arc. By digging into the snow, the arc forces you to turn. Bigger sidecuts (wide shovel/tail with narrow at the feet) are easier to turn because they have a smaller radius of curvature.
Put a big wide ski, made for powder, on hard snow, and if you’re going to carve the turn, you’ll have to lever the ski up onto the edge. And the author’s point is that this takes a huge amount of strength to do and hold, because the edge has more leverage on your foot. One must counter that leverage with force, muscular strength to hold the ski up on it’s edge. Very few people are strong enough to do that, so instead of carving the turn, they have to skid the turn.
I guess if wide skis are all you have, it’s better than not skiing. But skidding your turns isn’t good skiing, and the increased leverage of the ski on you does make it more likely to hurt something (mainly ligaments). The article seems kind-of out of sorts, though, in that I think the proper conclusion (which he says in the video) is to have the right kind of ski that matches the conditions you’re skiing in. About the same as boards fins and sails!
I have not comment on whether or not foiling is bad for knees, because I don’t know what Scott’s ideas are. Two things that do greatly concern me about foiling are: 1) forefoot fracture dislocations, and 2) foil lacerations. A Lis-franc injury is a very bad day and will keep you out for many months, and lacerations can be disfiguring and lethal. A foil has an immense amount of leverage (i.e. moment arm), which is why at slow speeds it can hold you and your board and rig up in the air. If that were unintentionally focused onto your foot/ankle, you are not going to come out well. And pain is not always temporary, which is why we have an opioid epidemic. I seriously doubt that I would use footstraps on a foiling board, but would ride one more like an WindSUP. Then again, take a look at Balz Muller foilstyling (links below).
Lis-franc’s:
Laceration:
https://www.theinertia.com/surf/heres-what-happens-when-a-foil-board-hits-you-in-the-face/
Foilstyling
https://www.youtube.com/watch?v=LNfnI5PWVzU
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Geoff, I was trying to get this post past the admin., should have elaborated more about the parallel I though I saw in this article about wide skis hurting your knees. In short, the more upright stance wide skis skiers often adopt and the upright stance I often find myself using on foil make the knee less able to withstand some the loads placed on it. As I understand it a flexed knee is better supported by the muscles and ligaments surrounding it. My layman’s interpretation of the situation! Then again maybe I’m just getting old, cause everything hurts! lol
PS good advice on fin, I was looking at an MFC Liquid Pro similar to sweep fin you mentioned.
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My price is better!
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Informative read and opinions you guys. I’m in the market for some new skis and this helps inform my decision with sore knees in mind.
Wd
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Get the right skis for the snow.
Scott’s problem COULD be due to localized arthritic degeneration of knee / kneecap cartilage. Can’t say more with what I know, no exam, no imaging of the knees in question.
As an aside, I would say that I’ve seen (and have done some research to show) that non-articular sources of pain are significant in a lot of people. In non-medicalese…soft tissues (ligaments, bursas, muscul0-tendinous junctions, etc.) cause a LOT of pain in a LOT of people, most of whom don’t have clinically significant joint destruction (i.e., loss of the shiny, rubbery, slippery cartilage on the ends of the bones). In general, I would bet on that problem first, and articular problems next. But figuring that out requires a good sports medicine or ortho doctor.
Your low-value American health care system, which provides the worst $/benefit value on Earth, is woefully inadequate at A) diagnosing this problem, or B) helping you make it less bothersome.
GEM
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