 Poster: A snowHead
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Interesting research on this, see article.
Quote: "John Seifert, an associate professor of health and human development and avid skier at Montana State University, researched the effects of wide skis on knees and ankles. Using leg sensors, Seifert monitored muscle and joint strain on skiers.
Seifert said when skiing hard-packed snow on a ski wider than 80 mm underfoot, the force needed to turn the skis puts an undo amount of stress on knee and ankle joints. “It appears right now there is a threshold in the mid 80s, and an additional lever arm,” Seifert said. “That additional lever arm provides extra torque, and is causing sore knees and ankles.”
Whilst fat skis are undoubtedly a great aid to powder skiing, is the trend to using ever wider skis by on piste skiers a triumph of fashion over functionality....?
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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John Seifert should try skiing on a dry slope. A lot more force required to turn than a fat ski on hard packed snow.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| Alastair Pink wrote: |
| is the trend to using ever wider skis by on piste skiers a triumph of fashion over functionality....? |
for me it's hope over expectation - i want to have the best tools for the snow i'd like to ski, even if i sometimes end up using them on hardpack. if i had somewhere in the alps to store a quiver of skis, it might be different
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Not sure. My injuries have certainly been wider recently.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Food for thought here !
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It's a "silver bullet" to improve your off piste skiing, so folk are, IMHO going wider when a decent pair of < 80mm skis will do for most skiing, inc a touch of off piste..
For solid days out with a guide I use wide skis, for skiing around resort I use 74mm underfoot which has done me fine in all conditions !
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@Joy Zipper,
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A lot more force required to turn than a fat ski on hard packed snow
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Not my recollection from the years when I used to hang around at Hillend. And, it's a different set of forces he's talking about I think.
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I caused (without realising it until I tried to get out of my car after a long-ish ride home) considerable damage to my knees, testing a pair of Whitedots at MK. I'm inclined to believe this article, though was slightly alarmed by his mid-80s threshold - my all-mountain skis, which I use all the time, are 85 underfoot.
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@Pedantica, My new AM skis, which I've now used for two weeks (mainly on piste) without problems and without feeling an additional stress on the legs, are 88 underfoot. I think a lot may also depend on the shape and construction of the skis.
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...and of the skier, Pedantica !
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Surely on hard packed snow, the forces you have to apply are also, and possibly more associated with the ability of the ski to turn easily?So a fat ski with a smallish turn radius doesn't put as much strain on the knees and ankles compared with a narrow waisted downhill ski with the kind of huge turn radius now required by competitive downhillers.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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Sounds like he got a research grant to go skiing during the day, and state the obvious, top work that man 
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Perty, No, a fat ski will put more force on the joints than a narrow one.
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You know it makes sense.
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@Perty, it's specifically the lever (or castor) effect that he's talking about. You need to add extra force because by putting your ski on an edge you are actually lifting your body up.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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This isn't really saying anything that isn't pretty obvious, wider skis impart more force on your joints, the magic number of 80mm is interesting. The risk factors of this additional load are also going to be different depending on how regularly you ski and how strong in general your legs are. Will be interesting to see what sections of the skiing population do see an increase in actual knee injury from the increased strain involved of skiing with fatter skis.
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Poster: A snowHead
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108mm for flying about and hopping on and off piste into the slack and go-anywhere resort skiing, 118mm for big powder days...........my knees feel absolutely fine, no mention of materials or construction in the above which I would have thought could be equally a contributory factor. I ski carbon, I reckon that makes a difference, lighter and responsive I feel, I've yet to find them "bad in crud, bad on ice, don't carve, too whippy, unstable at speed etc", all the things sometimes levied at carbon skis...................well done Whitedot is what I say, loving 'em! 
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Oops! Just bought some 110s as i seem to be hoping for soft and fluffy stuff more and more, but my knees complain bitterly anyway. Hope I haven't done the wrong thing. 
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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There's no numbers, methods or science in that article?
I think there's too many parameters to make such a general conclusion about fat skis. If I'm on my skinny sl skis my on piste skiing will be very different to when I'm on my 108mm, in terms of turn shape and my general desire to carve or skid. it ain't like for like.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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I do get sore knees skiing wide skis on hard snow and the lever effect makes sense to me - esp if you can ski quite fast, actually carve with wide skis and weigh a few kg. all adds to the forces your knees need to deal with
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I tend to agree with the comment because when on any ski the force is not in a straight line through the leg to the turning edge. On a fat ski the fatter you go the more accute this diflection and so their is the torque effect on the first part of the body that potentially can move in line with that torque ( this is the knee ).
The harder the snow the more this will be apparent as you will be less able to bank the snow under the ski durring a turn. This is because even though the edge carves you generate a force into the snow which dependant on how hard it is will dictate how much it gives, this build up is best described as a banking that the base of the ski glides along. In softer snow this banking can be the width of the ski in harder snow less and on ice almost non existant.
If you have the snow compressed/banked under the ski base it aids in the alinment I mentioned above ( because some of the force is going into the banked snow thus lessening the angle ) if it is non existant it can not. So on piste is why you will face a greater risk of knee injury skiing on fattter skis.
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of course the number of injury's have gone up, those people on those fat skis (I think they are called snowboards) keep falling over, it can't be good for them
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| Joy Zipper wrote: |
| John Seifert should try skiing on a dry slope. A lot more force required to turn than a fat ski on hard packed snow. |
I'm fairly sure that if your were able to spend the same amount of time moving on a dry slope in one day as you would achieve on one day on the snow, the forces would soon become crippling! And if you used a fat ski on the dry slope the forces would be magnified.
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I suspect Perty, is close to the truth. On my previous pair of skis (90mm under foot, 19m radius) I'd have hot, hurty knees at the end of the day. On my current daily driver skis (112mm waist, 15m radius), I never have sore knees but my quads hurt more at the end of the day, though probably due to skiing much steeper terrain with admittedly questionable technique 
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@Neiltoo, why? I used to spend loads of time on a dry slope. Although in Scotland so it was often raining. Forces involved were not so very dissimilar to snow.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Regardless of the science, this is the same experience I have, which is why I mainly ski on piste with my black stars - when planning a majority offpiste day I go wider, but avoid otherwise. That said, my knees are already not in great shape, skiing a narrow ski just reduces the effect of skiing all day vs wider skis on piste.
That said, I am quite sure that good technique could make life a bit easier, skiing with a couple of others on 100mm+ width skis on piste last week they were not doing more work than I was, but they were angulating better than I do and carving more than skidding.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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| under a new name wrote: |
| @Neiltoo, why? I used to spend loads of time on a dry slope. Although in Scotland so it was often raining. Forces involved were not so very dissimilar to snow. |
Friction. I'm no scientist but from experience the forces on dendix etc are much greater. I raced fairly regularly at Hillend in my youth, a mate decided to tuck from top to bottom to see how hot his skis would get. They literally melted, they delaminated after the one run. That sort of friction must surely put much greater stress on the joints?
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It's all about using the right tools for the job.
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You know it makes sense.
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Ive always been fascinated by the growth in 'fat' ski use, either on piste or off. Fat skis make it easier to ski deep snow but why does everyone want it to be easier? I'm getting on now but I learned to ski the mountain on one pair of skis - 67 to 70mm or there abouts, by learning to ski everything on the one pair of skis your technique had to cope with all conditions.
Genuine question: Why is easier better?
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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Hmm...having now read the article (which I didn't before my earlier post  ) I read the following:
"Seifert also said wide skis can't make as sharp of turns as a narrow racing ski, which causes longer periods of flexing for ankles and knees". Still makes me think that it depends on the radius and stiffness of the "narrow racing ski", as well as the overall running length of the fatties. Though I would concede that, if I am skiing on a pair of 155cm 13m radius piste skis (which I haven't for years), it's a lot less hard work than my 105mm 167cm fatties with a radius of 19.5m, even though they are twin tips and have a shorter running length. It makes me think that it's time to invest in something more old school to see how they now feel.
If however, I am Lindsey Vonn (the resemblance is uncanny....)-check out the following link for some of the minimum dimensions and radii for the Downhillers:
http://www.the-raceplace.com/v/vspfiles/downloadables/FIS-Alpine-Equipment-Regs.pdf . Think my knees and thighs (and I guess ankles) wouldn't last 5 mins on a minimum radius of 50m and length of 205.
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Poster: A snowHead
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@Neiltoo, Haha - no but it sure puts more stress on your bases. Tucking from the top pretty punchy too - at least, it was in my day...
The forces that the investigator is talking about are resultant from the castor/lifting effect of wide skis. Dry slopes will have more friction in a forward direction sense but significantly less grip laterally. I don't see how either of those adds up to more stress on the kneess, if you're skiing properly.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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| Perty wrote: |
Hmm...having now read the article (which I didn't before my earlier post ) I read the following:
"Seifert also said wide skis can't make as sharp of turns as a narrow racing ski, which causes longer periods of flexing for ankles and knees". Still makes me think that it depends on the radius and stiffness of the "narrow racing ski", as well as the overall running length of the fatties. Though I would concede that, if I am skiing on a pair of 155cm 13m radius piste skis (which I haven't for years), it's a lot less hard work than my 105mm 167cm fatties with a radius of 19.5m, even though they are twin tips and have a shorter running length. It makes me think that it's time to invest in something more old school to see how they now feel.
If however, I am Lindsey Vonn (the resemblance is uncanny....)-check out the following link for some of the minimum dimensions and radii for the Downhillers:
http://www.the-raceplace.com/v/vspfiles/downloadables/FIS-Alpine-Equipment-Regs.pdf . Think my knees and thighs (and I guess ankles) wouldn't last 5 mins on a minimum radius of 50m and length of 205. |
Again, I re-iterate my lack of science knowledge but if you forget about the actual turn and just think about how far the knee has to travel side ways in order to get a 80mm ski to move from one edge to the other compared to say a 100mm ski moving from one edge to the other, the difference is substantial, I assume that the greater distance travelled causes more leverage and force on the knee.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| under a new name wrote: |
@Neiltoo, Haha - no but it sure puts more stress on your bases. Tucking from the top pretty punchy too - at least, it was in my day...
The forces that the investigator is talking about are resultant from the castor/lifting effect of wide skis. Dry slopes will have more friction in a forward direction sense but significantly less grip laterally. I don't see how either of those adds up to more stress on the kneess, if you're skiing properly. |
I get what youre saying and I couldn't explain it scientifically but it always felt to me as if there was more stress on your knees! Maybe just in my head
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| Arno wrote: |
| I do get sore knees skiing wide skis on hard snow and the lever effect makes sense to me - esp if you can ski quite fast, actually carve with wide skis and weigh a few kg. all adds to the forces your knees need to deal with |
Same here. I save fat skis for powder days now and am going narrower for on-piste or mixed days. I don't want to go down to 80mm though, narrow (for me) is > 100mm.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Neiltoo wrote:
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Fat skis make it easier to ski deep snow but why does everyone want it to be easier? I'm getting on now but I learned to ski the mountain on one pair of skis - 67 to 70mm or there abouts,
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But you wont be able to keep up with someone at the same level of skill who is on fatter skis, and do you not think people who are as good as you at skiing or better even use fat skis off piste?? I do and I don't think it's to make it easier.. 
Last edited by Anyway, snowHeads is much more fun if you do. on Thu 12-02-15 17:59; edited 1 time in total
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@Neiltoo, you could look at them as making it easier, or you could say they allow you to do more things for a given ski level. i'd be able to do bouncy bum wiggling turns in powder on skinny skis (I hope!) but I wouldn't be able to mess around with turn shapes, slashes etc which I can with fatter skis. and fatter skis allow me to enjoy less than ideal snow conditions, which would be a complete chore with skinny skis
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Brits seem most at risk as a disproportionate number are skiing fat skis on piste compared to locals
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You'll get to see more forums and be part of the best ski club on the net.
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Right on Q TTT enters with some thinly veiled xenophobic/wind up remark trying to provoke as usual.
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Ok, so why then if not to make it easier? I take your point re. speed but i like turning, especially in powder so not looking to ski faster. Each to their own I guess!
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Because it's more fun & better and as Arno says you can do things you cant really do on skinny skis, just like if I said you should ski a slalom on some 98mm skis you would say why would I do that when I can use a 64mm toothpick, making it easier for yourself in the process? or just making it more fun for the situation, thin fat ski arguments are as bad as ski/snowboard arguments or TTT's lame attempts to make everything about nationality
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