Float and Velocity and Equipment Choices

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Float and Velocity and Equipment Choices

Postby jbotti » Sun Sep 25, 2011 9:52 am

I have not run these comments by Harald, but I feel reasonably confident that he will be in agreement with most or all of what I am saying. And if not, I am happy to hear the corrections.

I learned something last year that is actually quite obvious so it's not surprising that it took me 9 years of skiing to figure it. When skiing 3-D snow (powder, fresh snow and soft crud) the skis need to come up enough out of the snow so that they can release and so that the skier can tip the skis on edge to initiate the next turn (release, transfer and engage). The relationship between float and velocity is an important one. Most intermediate skiers that try to ski in powder on skinny skis find it very challenging. Many advanced/expert skiers don't find it very difficult at all. The reason why is speed or velocity. At a high enough speed, even the skinniest of skis will plane enough to allow release and transfer and re-engagement onto the other set of edges. Having said that, if you are on thinner skis and you feel uncomfortable with skiing at a faster speed, then it is likely that you will not plane high enough to make RT and E free and easy and the skis will get caught up in the snow. Now add to this some other potential issues that intermediates may bring with them into 3-D conditions (like poor fore-aft balance, or rotating the upper body, not releasing the stance ski causing a stem) and without enough speed on thinner skis it can get ugly fast.

In PMTS the goal is to get the bullet proof short radius turn bullet proof enough so that the skier can ski at terminal velocity and continue to make short radius turns. Terminal Velocity is a term Harald uses. It is the speed one arrives at doing SRT’s. It is also the speed at which one stays at as long as the rhythm and pace of the SRT’s stays the same (hence a terminal speed that does not increase). This is the goal for any PMTS skier in steep difficult off piste conditions. In steep terrain the speed may seem high at first but if the skier stays diligent with SRT’s that speed will not increase. If you watch HH and Diana ski pow this is how they do it. Max has mastered this as well. I can do it on dark blue terrain for 15 turns but not always on black terrain. So again from the PMTS perspective, the goal is to ski at terminal velocity using the bullet proof short radius turn. And this is a lofty goal for any skier. It took Max years and I am still working to get there.

So when looking at the issue of equipment when one is focusing on skiing this way, it is very simple. Sidecut and TR actually become more important than float!! I will say it again, when skiing at terminal velocity with BPSRT's sidecut is actually more important than float. The float is coming from the speed and at terminal velocity, almost anyone at any weight will have enough speed to plane high enough to RTand E all the way down the hill. No one is ever going to claim that this is easy, but it is the goal. And anyone that gets there (even if it is only for 15 turns at a time) will tell you that it is an amazing experience.

So it absolutely follows that if you can't or don't want to ski at terminal velocity then you will need more float than the skier who is skiing at TV. This is why wide skis got popular in the first place. Speed will eliminate many issues that 3-D snow will throw at a skier. Without the speed we need more float. Add to this the issue of size and weight and 6 4" 220lb guys that don't want to go fast need a lot more float to be able to plane high enough in the snow to RTand E.

So there is no doubt that skiing on fatter skis can makes things easier in 3-D snow especially for the skier that wants to ski at slower speeds. You can ski at a slower more leisurely pace and not need to work as hard to get the skis to plane high enough to make turns. But it is important to remember that in PMTS, that is not the goal. The goal is to ski at terminal velocity using slalom turns in Pow and Crud to control one’s speed.

It is also true that generally the longer and wider that you go, the wider the TR of the skis goes. What you gain in float you are losing in edging ability. So if you are on a 192cm ski that is 120mm underfoot and the TR is 36m, you have great float but you are also skiing on a plank and the natural TR is that of a super G ski. In PMTS we are trying to ski slalom turns in steeps in 3-d conditions (again at terminal velocity). This is very simply why Harald Harb has hated fat skis for so many years. He is giving up so much in TR and because he can ski fast he doesn't need the float. That's why he'd most times rather ski steep pow on his IM 78's than on a 30m TR ski. Can he ski it on the wide TR ski, of course, but he actually has to work harder because he can't use the sidecut of the ski to help him turn the skis.

Rockered skis: Does rocker give more float? Yes. So this makes it easier to ski at slower speeds and still be able to RT and E. But from a PMTS perspective rocker (especially rockered tails) come with another set of issues that complicates it for PMTS technique. Rockered tails make it incredibly easy to slip, pivot and steer the tails, so easy that this often becomes the default move for many skiers that are on them. This is very important factor. Rockered skis and especially rockered tails respond better to pivoting that to tipping. In PMTS our first and primary movement to initiate any turn is to tip first and ask questions later. On some rockered skis it is almost impossible to tip without the tails sliding out because they respond so quickly to any lateral pressure. So on skis of this nature the skier will start to adapt to the natural pivoting that is occurring in each edge change and the skier is now watching and listening to how the ski pivots and no longer to how much the skis are tipping.

Something that I haven't mentioned is the necessary component of counteracting forces and counter balancing forces in good PMTS skiing. When skiing SRT's at terminal velocity, there is no steering. There is only flexing to release and the CA and CB forces naturally move the skis to their new edge. This is the only way that a skier can actually do slalom turns or BPSRT's at speed. Everything needs to be lined up with upper and lower body separation. It is hard or impossible to steer skis into turns at these speeds. Rockered skis (again especially tail rockered skis) are designed to be pivoted, smeared, steered and slarved). So when a skier skis on a ski that not only does not require proper CA and CB forces to initiate the edge change, but actually requires some modest amount of rotational force (that is what steering, pivoting, slithering, slarving and skarving require) this is why we will say again that rockered skis do not promote good PMTS technique and in fact promote the opposite. Again there is more than enough float available for any skier that wants a ski without rocker (at least at this point in time), but what attracts people to rocker is the amazing float and the ease with which the skis will pivot, smear, steer, slither, slarve and skarve, (all of which we try to avoid in good PMTS skiing)

The great news is that there are excellent 3-d skis available that do support PMTS technique. PMTS skiers that want to learn how to ski at TV should be choosing skis that support this, with no rocker and tighter turn radii. The skis that come to mind are the Icelantic Shaman and the Movement Pariah and Jam. The Head Peak 78 and Peak 85 also fit into this discussion. (Ski Logik makes quite a few skis with tighter turn radii but I have yet to try them. Perhaps I can try them and get Harald on them this season.). My goal is to be able to ski any condition on any ski (within reason as I don’t want to take my ISL RD slalom skis into a steep powder ridge and ski it. It may be possible but it will never be fun!). Perfecting the BPSRT is what it is all about and getting there happens on skinny skis as it is harder to do them correctly on wider skis.
So it’s pretty simple: if you want to ski better in steep powder and more difficult off piste conditions and maintain quality PMTS technique, stay off of tail rockered skis. Stay on skis that support tipping as the first and primary movement and use these skis to perfect the BPSRT. If you want to ski at speeds slower than terminal velocity, get a wide ski that has no tail rocker and has a tight turn radius and a god flex pattern like the skis mentioned above.

And as always and most importantly, do the drills and truly master the bullet proof part of SRT’s!!
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Re: Float and Velocity and Equipment Choices

Postby HighAngles » Sun Sep 25, 2011 7:05 pm

I agree with you for the most part. Thanks for taking the time to write that lengthy post.

We must all keep in mind though that "rocker" today comes in many, many forms. We all need to define exactly what rocker profile we are actually referring to when discussing rocker these days. I discount any discussions about "rocker" using any kind of generalized blanket statements because all rocker is not alike.

In regards to the comments about tail rocker I agree that when tail rocker is combined with 0 camber or reverse camber designs you end up with a ski that pivots first and doesn't bother to ask any questions later. :wink:
However, there are designs available that utilize full/normal camber along most of the ski and then incorporate tip and tail rocker. Note that these are NOT the models that currently boast "early rise" in their design. IMO those skis are just plain broken. All the manufacturers have done with those skis is bent the tips so that the tip may float up a bit easier in mixed conditions and is less "catchy" for the terminal intermediate type skiers. PMTS skiers will find that the tip engagement at the top of the turn is non-existent in these models.

There are, however, a few models where the tip has really just been extended further forward without killing the normal camber profile (even when the bases are pressed together). If anyone is interested in which skis those are send me a PM.

I test/use a lot of skis each season. I've been on plenty of horrible rocker designs, but there are some that provide some substantial benefits without all of the problems that would be damaging to a PMTS skier's technique. I certainly would not advise anyone trying to learn PMTS to go out and use any kind of rockered ski as their primary ski, but they do have their time and place for some skiers. I also advocate really deep sidecuts - especially on those wider skis. Skis with these characteristics are more difficult to find, but they are out there.
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Re: Float and Velocity and Equipment Choices

Postby jbotti » Sun Sep 25, 2011 7:47 pm

I agree that there are some skis with modest tip rocker (and camber underneath and no tail rocker) that ski pretty good and will not destroy your hard earned technique. They are still not skis that I go out of my way to ski or own, but it is getting harder to find wide skis without it.
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Re: Float and Velocity and Equipment Choices

Postby CO_Steve » Sun Sep 25, 2011 8:40 pm

In reading you post the question comes to mind just how much influence turn radius has in 3D snow? Of course some skis turn faster in these conditions but I've got to think flex, shape, etc come into play assuming you're not skiing on the bottom.
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Re: Float and Velocity and Equipment Choices

Postby HighAngles » Sun Sep 25, 2011 9:50 pm

The idea that sidecut is somehow irrelevant when you're in 3D conditions I find ludicrous. There's no doubt that the flex pattern, and any rocker profile present, has a major play in deep snow, but sidecut has just as much effect.

JBotti correctly points out the relationship between float and velocity over the snow. I would like to add that I don't feel that the holy grail in skiing is getting as much float as possible. I honestly felt that there were many times last season when I wanted to be deeper down in the snow, but at the speeds I was skiing my skis had too much float to let me get down into the snow. I am actually looking forward to more skis that have rocker profiles that are narrower, but still have full camber underfoot. Give me a ski that still skis hard pack like a solid SL ski, but when conditions go 3D provide me with enhanced float and stability with reduced possibility of tip dive. That's my ski nirvana.
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Re: Float and Velocity and Equipment Choices

Postby CO_Steve » Mon Sep 26, 2011 3:15 am

I didn't mean to imply sidecut had no effect, just how much? In thinking about the problem it occurs to me that a ski with a wide shovel and narrow waist will want to turn quickly in 3D snow. Not because it's riding a small radius edge but because of the shape. So yea, more sidecut equals quicker turns.
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Re: Float and Velocity and Equipment Choices

Postby Max_501 » Mon Sep 26, 2011 7:31 am

Great post by jbotti. Worth reading multiple times.
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Re: Float and Velocity and Equipment Choices

Postby robert5 » Mon Sep 26, 2011 8:14 pm

I want to point out another part of equation in pow, windblown, crud, etc.
I find that soft flexing slalom shaped skis tend to get too turny in denser powder with all the pow pressure developing mostly on the tails and tips. At one point I had to readjust DIN (heel piece) on my SS to prevent the bindings from poping.
Lots of people I know will not consider SL shaped ski for powder and will look for something with longer radius turn.
I think part of the reason may be that you get tossed left a right a lot and not that you will not stay afloat?
I am not trying to contradict, obvioulsy staying afloat must be a big part of what makes today's popular choice todays popular choice.

I only have SL shaped skis, and I found an SL alternative to straight powder skis which I just love.
Can a ski be soft and floaty at slow speeds (or light powder) and stiff when skied aggressively (or in denser windblown)?
I have a pair. Atomic Race D2 Slalom. The vari-flex thing is something I like a lot. One ski I love everywhere.
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Re: Float and Velocity and Equipment Choices

Postby Kiwi » Wed Sep 28, 2011 10:59 pm

John

Aren't you saying that you must have a turn shape that produces a terminal velocity sufficient for the ski to float in powder.

And that on a steeper slope you can use smaller turns than on a more moderate slope because on a steep slope the necessary TV to float can be obtained with smaller turns . This same TV will only be achieved from skiing more in the fall line on the moderate slope. [I know the physics aren't perfect but you see the point][I think on steeper slopes the necessary TV can be reached earlier]

Aren't we just saying each skier on his skis has a unique velocity to float in powder and you must adopt a turn shape(s) that produces the necessary TV for any given condition and steepness.

I agree that in some situations in powder on a steep slope with narrow skis that, even with a BPSRT, the TV could be unsettling until you get get the right experience/skills. On steeps in powder the TV from anything other than a BPSRT is likely to quickly become unmanageable.

Fatter/longer skis allow a TV for any turn shape that is slower than a narrow shorter ski, but in almost all conditions anything much over 80ish at the waist is giving to much away in versatility.

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Re: Float and Velocity and Equipment Choices

Postby Max_501 » Fri Sep 30, 2011 11:29 am

A few comments I made over on the realskiers forum that are applicable.

----------------------------

The terminal velocity jbotti is referring to here is skier related. Combination of factors including gear. In a general sense we'll say you have five turns where you are allowed to accelerate and then after that your speed should be constant. If your technique isn't spot on you won't be able to do this on steeper terrain.

Could be a brushed carve or an edge locked carve. Doesn't make any difference. The key is using the movements to work the ski. If you don't work the ski you'll end up gaining speed with each turn.

----------------------------

There's plenty of resistance in most 3D conditions to bend a ski that has a nice flex pattern. For a traditional design, the more sidecut the more the ski bends. The wider tip/tail have less weight on them and more surface area to be supported by the snow. The waist has a lot more weight and less surface area so it sinks more into the snow.

Demo different skis until you find some that feel good for the type of skiing you do. You might like a really soft ski in fresh light pow but find that you hate it in chowder and crud because the tips/tails bounce too much. You might find you love it in pow but hate it on the groomers.

----------------------------

Regarding the role of sidecut in pow. All you have to do is take a run on 30M ski and then on a 15M ski, with a similar flex pattern, to see the difference. It will be huge.
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Re: Float and Velocity and Equipment Choices

Postby serious » Tue Oct 18, 2011 3:24 pm

HighAngles: However, there are designs available that utilize full/normal camber along most of the ski and then incorporate tip and tail rocker. Note that these are NOT the models that currently boast "early rise" in their design. IMO those skis are just plain broken. All the manufacturers have done with those skis is bent the tips so that the tip may float up a bit easier in mixed conditions and is less "catchy" for the terminal intermediate type skiers.

This makes no sense. Early rise and "rockered tip" is the same thing. Both have normal camber, but the tip goes higher than a traditional ski to effectively get you some float. "Early rise" skis can have excellent engagement if designed correctly. And by "design correctly" I mean that the widest par of the ski is still part of the cambered section. Heck, even some race skis have early rise today, effectively allowing manufacturers to cheat on the length. I am sure it is a matter of time before FIS will have to update length specifications. :D

Anyway, I don't mean to take away from the original post. I fully agree with the post. I think sidecut is critical in getting you to turn in any conditions, and the new trend toward "early rise" tips just means that the tips go higher off the snow. But since tipping is the main ingredient behind a turn, a reasonably wide tip and some "early rise" will also help you to turn in the deep.
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Re: Float and Velocity and Equipment Choices

Postby h.harb » Tue Oct 18, 2011 4:34 pm

John did a great job explaining the virtues of velocity and flexing. With this combination, tipping, with the legs following the tipping action, and a CA'ed hip and torso, everything gets real easy. I've seen first hand what the wide skis do to skiers when it gets steep and the snow isn't perfect; they revert back to rotation and big toe edge. Next comes the upside down moment, when everything stops.

You may have upside down moments learning the PMTS way as well, but at least you are headed in the right direction with the right movements. The alternative is, you'll never achieve what you want in skiing. John can attest to the technique working, I think I skied on everything from a TT to a Shaman last year, including K2 and others. My technique never changed, and we skied everything, but I had to work so much harder to keep the shinny side up on many of those products. If you want to ski tight turns on steep, in heavy powder, because Champagne isn't always that readily available, you have to learn to flex to release, get the skis flat and tip to the new side. Don't help the skis into the top of the arc with the upper body or pivoting! This all happens with the right movements. You don't have to think turning or pivoting, only those who don't know how to ski, or anything about real skiing, think about pivoting. Stay on course, flexing and tipping.
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Re: Float and Velocity and Equipment Choices

Postby HighAngles » Tue Oct 18, 2011 7:42 pm

serious wrote:HighAngles: However, there are designs available that utilize full/normal camber along most of the ski and then incorporate tip and tail rocker. Note that these are NOT the models that currently boast "early rise" in their design. IMO those skis are just plain broken. All the manufacturers have done with those skis is bent the tips so that the tip may float up a bit easier in mixed conditions and is less "catchy" for the terminal intermediate type skiers.

This makes no sense. Early rise and "rockered tip" is the same thing. Both have normal camber, but the tip goes higher than a traditional ski to effectively get you some float. "Early rise" skis can have excellent engagement if designed correctly. And by "design correctly" I mean that the widest par of the ski is still part of the cambered section. Heck, even some race skis have early rise today, effectively allowing manufacturers to cheat on the length. I am sure it is a matter of time before FIS will have to update length specifications. :D

Anyway, I don't mean to take away from the original post. I fully agree with the post. I think sidecut is critical in getting you to turn in any conditions, and the new trend toward "early rise" tips just means that the tips go higher off the snow. But since tipping is the main ingredient behind a turn, a reasonably wide tip and some "early rise" will also help you to turn in the deep.


Early rise and rockered are not the same in most skiing circles. Go into any shop and ask to look at the early rise models. Then ask to look at the rocker models. They'll bring you two different sets of skis.

Maybe I didn't communicate what an early rise ski is clearly enough so let me try again. An early rise ski is usually absolutely the same as a normal camber, traditional sidecut ski except the only change to the ski is that the tip has been bent up; no changes have been made to the sidecut, the tip/tail profile, or the suggested binding mount position. This leaves you with a ski that has no real tip engagement until significant edge angles are achieved. Early pressure to the very tip of the ski is virtually impossible on hard pack conditions. Very few "early rise" skis still have the widest part of the ski within the cambered section. I typically test well over 50 pairs of skis each season and most early rise skis that have more than "marketing" rise are not designed with widest portion of the tip still in contact with the slope when decambered.

There are, however, a current crop of skis that have full camber underfoot with rockered tips and tails (with clearly observed amounts of splay) and early taper on both ends. These skis ski effectively the same on hard pack as many traditional skis since the rockered tips and tails don't play into the equation in these conditions. The sidecut has been adjusted to marry well with the rocker profile and with the tip and tail taper. The binding mount position has also been well thought out to sit in the correct position in regards to the sidecut and the cambered section of the ski. You could chop off the tips and the tails of these skis and be left with pretty much a fairly standard ski (although it most likely would be wider).

There really is no comparison in my book. The early rise skis just feel plain broken to me and for PMTS skiers they buy very little in the way of improvements for all-terrain skiing. If you really need a crutch to ski powder then pickup a "funshape" ski (camber underfoot with rockered tips and tails), but for most folks on the PMTS forum there really is no point in heading in that direction if you're working on improving your skiing.
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Re: Float and Velocity and Equipment Choices

Postby serious » Wed Oct 19, 2011 7:36 am

HighAngles,

Sorry, I was completely wrong about the widest portion of the ski being part of the camber. But when I look at rockered tip and early rise models, I see no difference at all. I do realise that a rockered ski (reverse camber ski) is completely different however.

Speaking of early rise, last night I compared my Salomon SW Enduro (it has “early rise technology” :roll: ) with my Elan Mantis 662, both 170 cm long. There is almost no difference in the length of the camber (the Salomon is slightly longer at the tail end). The only difference is that the Salomon tip goes higher (as in higher off the snow). Why would that be a broken design, especially since it has crept in racing?
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Re: Float and Velocity and Equipment Choices

Postby Max_501 » Wed Oct 19, 2011 11:14 am

Trying to analyze the differences in the early rise and/or tip rocker skis based on a visual inpsection isn't likely to yeild useful results due to material design differences that you can't see.
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