Which is faster - skiing on edge or with flat skis?

A snowHead

I was under the impression that skiing with skis flat was faster, but someone on the Fear thread suggested that skiing on your edges could be faster as a smaller surface area means less friction. Anyone care to discuss?

A snowHead

Depends if you are turning or going straight

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little tiger, makes a good point so to clarify - I'm not talking skidding I'm talking skis carving versus skis flat.

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The fastest downhillers on the flat sections of a course are those who can best ride a flat ski. The skis are running fastest when you can feel them floating a bit side to side. But when doing that they're simply riding the falline, not turning.

When turning, speed is all about how clean your carve is. Any skid, even miniscule amounts, constitutes braking. Carving quality being equal, a smaller radius (larger edge angle) equates to slower speeds.

One exception is that on a very flat slope or cat track it's possible to ski faster by pumping turns than by going straight on flat skis.

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little tiger,

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I think there are some situations where an edged ski might be faster than a flat ski, such as skiing warm, wet snow on gentle terrain. An edged ski would provide less contact with the snow, so less stiction.

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rob@rar, ah but then you also have to allow for the fact that skiing on an edge means a significant increase in ground pressure which is likely to increase stiction.

I'm not sure there is a definative answer, it will depend on many things not least of which would be piste conditions, a hard race prepped piste will offer significantly less resistance to a soft spring snow piste, so on a hard piste the chances are that smooth edge to edge carving may be faster, whilst on a soft wet piste you are better off trying to glide over teh top as much as possible with skis flat

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OK, I think I get what you're asking, beanie1. Let's stick to your GS course scenario. The biggest difference in the speed comparison of a round arc to arc line, vs a sharp turn/straight/sharp turn line, is in the shorter distance covered. Even with that straighter line there will not be much time spent on a flat ski. A lower edge angle between the sharp turns, perhaps, but very little time totally flat.

Have a look through the montages here on LeMaster's site and you'll see what I mean.
http://ronlemaster.com/images.html

D G Orf, yes that's right. I don't have an empirical answer, just experience that in those kind of conditions keeping the skis on an edge feels faster than keeping them flat. But anything which can only be determined by the clock is only of relevance to those who are racing, IMO.

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rob@rar, and I'll concur with your experiential observations.

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beanie1, something thing I failed to mention is another reason that the straighter line is faster, in addition to the shorter distance covered, is that you're not fighting gravity as much as you are on a higher/rounder line.

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FastMan, So a flat ski is only faster as with a flat ski you can go straight down the fall line, whereas if a ski is on edge you will be turning so covering a greater distance? But if that is the case would it not follow that a faster ski would be one with a smaller surface area = less friction? Which is the opposite of what is used for speed skiing.

(Right I'm getting too near the realm of physics and ski design which is not normally my thing! Hope skimottaret doesn't spot this Embarassed

)

Am I right in thinking the opposite is true on a dry slope, ie edges quicker than flats?

You know it makes sense.

beanie1, im no physics guy, have to say those arguements do my head in but i do like a bit of ski design and equipment set up geekiness. wink

As proof my next job in the garage is to dismantle my new GS skis so i can set em up right. Embarassed

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Mountain Haddock, Because of the greater friction, yes edges are much faster than flat on plastic - which leads me to think that the difference in speed between edge and flat on snow will depend on the amount of friction - how well waxed the bases are, type of ski, type and smoothness of snow etc.

A snowHead

flat ski is always faster if you are pointing downhill

A snowHead

beanie1, there are so many factors involved, it can get very confusing. I'll lay out some general truths, and you can then compile them into a game plan, for what I imagine is a race success quest?

- When running straight down the falline, flat skis are faster, because if you're riding your edges at all, you're fighting your skis desire to turn. You're always having to manually twist them back and keep them going straight, which creates drag.

- A longer ski will generally be a faster ski, because it creates more float when running flat,,, carries more mass and momentum across the flats,,, is more stable,,, distributes the force load across a longer surface area while turning so the ski cuts a shallower platform into the snow, so it arcs with less resistance,,, doesn't get overloaded by the turn forces as easily through a turn and wash out,,, provides a stronger release energy as you exit the turn.

- A longer ski will only provide benefit up to the point that you can bend it to get the turn shape you need to be fast. This is why we have different cut and length skis for different events. A slalom ski would be slow in a DH because it wouldn't float well. would get overloaded, turn too sharp and take little energy out of the turn, and would be down right dangerous. A DH ski would just never be able to make the turn shapes needed to be fast in a slalom course.

- Line and and a clean edge are crucial. Carving will always beat skid, regardless of line, but if you can hold your carve, straight wins the day.

- Base prep is over major importance when it comes to speed.

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beanie1, basically if you want to go fast use the following 3 rules:

1. Whenever possible go down the fall line with a flat ski

2. When you have to turn carve as smothly as possible

3. Avoid skid turns at all costs

Hovever there is a proviso, it doesn't matter how fast you can go if you can't complete the run without falling over, so all of the above rules can be ignored where safety comes into play for both yourself and those arround you

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FastMan, I'd guess 0 delta on his bindings.

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FastMan, they are atomics and thankfully already at .5 and 3 which is what i would have gone for but as rob@rar, says i need to shim em a few mm to get flat and move the bindings a lot more forward.

These and the last pair of skis i have bought second hand have come from a sponsored skier with tiny feet. The factory guys spot the bindings for his small feet and this puts the toe piece pretty far back. If i just adjust the binding to fit my bigger feet the heel piece goes back and i end up a couple cm's too far aft. i got all techy on this a while back but having my skis set up right definately seems to help me, sorry for the thread creep Embarassed

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FastMan,

Thanks for the explanation!

The fastest speed ever achieved on skis, 156mph, was done on flat skis.

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Whitegold, but going dead straight down fall-line... hence my first comment... It really does matter if you want to turn... because if you keep them dead flat you are not going to turn just splat into the trees/fence/building etc and if they are not quite flat - you are losing speed...

Try having skis dead flat and going cross slope.... (diagonal downhill will do) it is not as quick as down fall line... then think if you want to not drop below a certain spot(next aiming point) you are sometimes going to struggle if they are that flat (how often???) so what do you do?

beanie1, I once did the rather interesting exercise of standing in a suitable place that the edge change occurred right about my head level and straight ahead of me, for the Canadian Championships... at least for that gate those guys changed edge to edge awfully damn fast - I got made to watch the difference in edge change speed between the good ones(dead fast) and the also rans(less fast) .... but maybe nobody told them they should be on a flat ski???

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Of course on flat skis!
We are "slidding" but it's better to say we are rolling on the snow. When we are skiing we are creating a friction and this friction makes very very little balls of water under your skis on your skis base.
That's because we have different kinds of wax ; we don't use the same technic and not the same wax for waxing on cold snow or when the snow is full of water (spring conditions) or slalom skis or downhill skis.
A downhill racer try to keep his skis as flat as possible to "roll" faster.
Hope I have been clear, it is physics and it's not my job.

You know it makes sense.

I agree with rob@rar that skiing wet snow you go faster if you edge: this prevents the wet snow creating a continuous water layer which sucks onto the ski (this is assuming that there is enough of a firm base so that most of the ski remains above the snow).
I have noticed it is also true when indoor slopes get sticky (as at MK once when glycol got in the snow).

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snowball, and certainly true on a "dry" dry slope wink

Unless you like the smell of burning ptex of course......

A snowHead

Yoda, burning ptex just occurs along the inside of the edge if you're carving! More pressure on a smaller area.

A snowHead

Sideshow_Bob, pedant Laughing

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Yoda, not really, been there (Sheffield), done that (skied all day on a non-misted slope), bought the t-shirt (well, actually both the t-shirt and a new pair of skis after I melted huge chunks out of my existing skis underfoot on both sides near the edges). Shocked

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Even on wet snow, skiing flat is faster. Wet snow is normally soft, so when you are on edge, your skis go deeper and are digging into snow. Skiing on flat surface is always faster. Reason? As snowarea wrote, there's thin water layer creating between snow and ski base, so skis are actually not sliding on snow, but on water layer. With softer (that's what wet snow normally is) snow, skiing on flat is even more important, since weight is distributed more equally through the ski, so ski digs less into the snow. This way, you are making it faster.

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Well I did specify that there needed to be a hard base so most of the ski base stays out of the snow - but, given that, I stick by my statement about the sucking effect of too much water - it is the reason why the ski surface, when you get a service, is given a slight wavy texture - to avoid that. I can remember an occasions when I could pass people by putting in shallow carved turns, but remained slower with skis flat. Of course it does partly depend what wax you are using - perhaps with the right wet snow wax it wouldn't have happened. (Not being a racer I only own Universal wax at the moment - time I bought some wet snow wax perhaps.)

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Which is faster - skiing on edge or with flat skis?

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