edged ski verus flat ski

[fisherskionsnow]

which is faster a ski on edge or a ski that is flat?

[ibMED]

On p. xi & xii, Note to Racers, of Essentials of Skiing, Harald addresses this question very clearly. "Gliding with just enough edge hold, and edge hold without impeding gliding, are the secerets to winning runs."
From a practicle standpoint, if I'm on a long flat runout with the prospect of using poles to keep up speed, I do everything possible to keep my skis flat. Edge Hold scrubs speed assuming you are going staight downhill.

[ramshackle]

Yeah it really depends on what your trying to do if your trying to turn or trying to glide but pretty much the more edge engagement you have the more friction you have and friction is a speed scrubber but you have to have some edge engagement if you want to turn. In a race course there are other variables like line and in some cases a drifted turn can make you lose your line and that might be slower than a hard carved turn even though theoretically the carved turn may have more friction. Theres also the idea that some skiers have enough skill to milk the rebound from their skis and on a flattish section you can have that kind of skier go side by side with a skier whos just letting the skis run flat and within a few small turns the skier whos using rebound will start pulling away from the skier running flat so theres also that variable of using the skis energy stored in a turn to your advantage.

So overall its not as simple as a flat ski or an edged ski without more detail on what your trying to do and what are the snow conditions and what ski and what quality of edge tune on that ski.

[calmman]

Yeah it really depends on what your trying to do if your trying to turn or trying to glide but pretty much the more edge engagement you have the more friction you have

but you have less surface of contact....

[Arkady]

If I get it right, under normal conditions, in slalom and GS you go faster from edge to edge, never coming flat. In SG and DH there may exist straight stretches where you can gain speed going flat. On a totally straight run for speed you should go all flat

Same should be right for free skiing: shape of the run determines what is the faster way to go. Snow condition and turn radius then will tell you exactly how much edge you need. FWIW

[Max_501]

Wet snow can change things due to the suction it creates on the base. In that case speed is gained by being on edge.

[dewdman42]

Interesting discussion. Looking forward to hearing Harald's comments.

My feeling is that I ski much faster when I think about carving edge to edge. Edging does not create more friction unless you are skidding. Speed reduction can be controlled via turn shape. There are probably some laws of physics at play in the decision here, but at our level of skiing its more of a practical concern.

If you are carving, you are going to be going faster than if you are skidding. If you let your skis dwell in the flat zone too long I would probably contend that you're more inclined to get some skidding when you are ready to turn them. This is besides the obvious fact that if you are on edge you have less surface friction at play. In some snow conditions you might even get a bit of suction under foot if your skis are flat.

I'm no race expert, but my interpretation of the racing world talking about over edging is that there is a particular line through a race course which is the very shortest line. Racers do deviate from that line for tactical reasons in order to set themselves up for higher speeds with cleaner arcs or to approach upcoming gates which may require a tighter turn to make; or other challenges. For every gate there is an optimal line and optimal place to transition into the next turn.

Every nanosecond past the apex of the turn that a racer holds onto their carved turn, they are diminishing their overall speed (or increasing their course time) because they are turning away and resisting the urge for gravity and inertia to pull them down the hill. And if they hold on to that carve long enough, at some point that also goes too far beyond the optimal place to transition into the next turn to stay on the fastest line possible. The longer they hold that carve, the more they are resisting gravity and inertia. If they let go of the carve too soon they will be in a poor line for the next gate and will end up losing speed from having to take more poor lines until they can get back on schedule. So they have to resist gravity and inertia a certain amount for nearly every turn. But the trick is to not resist it one nanosecond too long.

Also, if they are over-edged, its that much farther for them to cross-over into the next turn during transition.

These are some of the reasons you will hear the commentators on TV talking about a WC racer holding on to their carve too long. I do not think it is because they feel the skis will somehow go faster then they are flat on the snow UNESS there is a tactical reason to drift without turning away from inertia. On the flats, they are largely going straight..there is no need to turn...so no reason to turn away from inertia..in which case, flat makes sense.

For recreational skiers, holding on to the carve longer before transitioning is in fact a powerful way to slow yourself down without skidding for exactly the reason I just described.

Its just way too simple to say that flat skis are faster than edged skis or visa versa, but I just know what when I ski and I think about skiing edge to edge, I ski faster in general. This is largely because when I ski edge to edge I'm achieving high-C turns. Without high-C you float on flat skis and then have to put them on edge eventually to finish the turn..usually with more skidding then you want, if your goal is to go fast.

[Ken]

The only time the skis should be flat on the snow is when skiing straight down the fall line. At all other times some edge is needed. As said above, the least edge to hold the line and avoid a skid is best.


Ken

[fisherskionsnow]

which is faster a ski on edge or a ski that is flat?

In Harald's new book the sample turn showed only one frame where his skis are flat. The other frames he was increasing or decreasing the edge angle. If he had two frames where his skis are flat, wouldn't he slow down due to friction and start to skid?

[h.harb]

If you have ever seen the Physics experiment where two metal balls are started in the same place at the same time, one follows the curved line, the other follows the diagonal straight line . The curved line, ball always wins because the initial vertical drop is steeper in the curved line. Once into the fall the curved line offers momentum to gain and maintain speed and the curved line ball is always faster. The straight line is shorter. This done in the falline and in a laboratory situation. But if you apply it to skiing. A carve is always faster then a skid. The more angled the ski the faster the same arc as a the skidded turn.
In the equation : V squared Velocity, over R, the radius of the arc, equals A acceleration or centripetal force.

http://www.harbskisystems.com/hhsite/eq ... 20copy.tif


The thing they don?t tell you in physics class is that the equation is dependent on the value R, which is in skiing, how you can tip and in what part of the arc you tip. Velocity is speed, so the faster you are traveling, the better your chances of staying upright in a turn, (with the same angles) again if you can tip the skis to at least an angle that works for that higher speed. . If you ski slower, it is more important to tip correctly, if you want to get big angles without falling over. So, if you should try to achieve a low R value (because in the formula it is divided into V), which means a smaller arc radius , you have to ski faster to stay upright with less edge angle.

As far as skiing with the skis flat, trying to complete arcs on green slopes, it is very slow. I have to really skid for Green Camp skiers, so my students can follow me in a series of turns, as I speed up quickly when I put the ski on edge, and they slow with less edge angle.

I often find myself in a bad situation on crowded slopes, as I?m arcing very round completed curves and I see someone out of the corner of my eye, beside me, skiing almost straight downhill, barely pushing the tails to the side staying with me, the whole run.

[h.harb]

Yes, of course, a straight down the falline ski is the fastest, but in the discussion I read, the question was about which skis were fastest when on some degree of angle.

[dewdman42]

I guess the original question was simply, what is faster, a ski on edge or a flat ski. There was no mention about whether the ski is going straight down the fallline or otherwise. However, practically speaking, there is not much point in discussing straight down the fallline. No duh that is the fastest way down and you can't even do it on your edges. What is the purpose of the question?

From a practical standpoint, we make turns and S shaped lines down the hill. Well, hopefully S shaped.

Here's a question. On a green run I can make S shaped turns down the same run that my buddy is going straight and I can keep up with him, yet I am traveling on a longer path. Who is going faster?

[fredm8]

Here's a question. On a green run I can make S shaped turns down the same run that my buddy is going straight and I can keep up with him, yet I am traveling on a longer path. Who is going faster?

Dewd,

In terms of simple physics, to travel from Point A to Point B in a straight line, then distance over time gives you a known average speed.
If you are carving shaped turns, then the distance travelled must be further than the straight fall line, so if your time is the same, you must be travelling faster across the snow.

Could the difference between skiing flat causing drag and suction is slowing down your buddy, whilst you are carving, with less surface area on the snow allows you to ski at a higher velocity. Then must be an effective trade-off between surface area of the ski on the snow, the suction of the snow, the effect of gravity pulling you down the fall line, and the efficiency of the ski edge.

Given the previous comment about speed skiing, what format of ski do they use. Long (240cm), cant find a profile description whilst Googling ...

Its all upside down to me

[h.harb]

A simple difference can be the ski base. I have race bases on my skis and most recreational skiers have standard multi use bases. If they don't take care of the bases, they get really slow. I wax mine once a week. On a flat slope, straight in the falline, I pull away from most of my clients very quickly.

[milesb]

A simple difference can be the ski base. I have race bases on my skis and most recreational skiers have standard multi use bases. If they don't take care of the bases, they get really slow. I wax mine once a week. On a flat slope, straight in the falline, I pull away from most of my clients very quickly.

It's the suit.