Rebound

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Rebound

Postby Kiwi » Wed Jun 15, 2011 7:15 pm

When I ski on the Super Shape I can feel rebound pressure through the release to transition. However, when skiing on a Stockli slalom ski or the Stocli Laser SC, the same length as the SSs, I do not get the same feeling of pressure. I am putting a lot of bend into the Stockii. Is this something I should try to address? Could it be that I do not have enough pressure on the stance ski in the lower C or perhaps the Stocki needs a more aggressive release.

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Re: Rebound

Postby Max_501 » Wed Jun 15, 2011 7:17 pm

Hmm...what does the rebound pressure feel like on the SS?
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Re: Rebound

Postby Kiwi » Wed Jun 15, 2011 8:11 pm

What I thought was rebound is the increased sense of load coming onto the foot as I flex. While the stance leg is extended I feel pressure but when I am flexing the feeling is quite different and I get the sense that I can control the release more precisely by regulating the pressure.

I know talking of feelings is difficult. Maybe this is not rebound at all and perhaps I am the only one!!

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Re: Rebound

Postby Kiwi » Wed Jun 15, 2011 8:22 pm

Max501, perhaps it is less load on the foot that I think I am controlling. What struck me was the variation between skis. I have skied Stockli for a longtime before trying the SSs.

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Re: Rebound

Postby Max_501 » Wed Jun 15, 2011 9:11 pm

My race stock skis have more kick (rebound) than my SS. By ALOT! However, they are not as forgiving so to get them rebounding I must work extra hard to stay forward. If I'm not foward they feel damp and lacking rebound.
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Re: Rebound

Postby Kiwi » Thu Jun 16, 2011 1:04 am

Thanks Max501 that gives me something to work on.
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Re: Rebound

Postby Matt » Thu Jun 16, 2011 4:51 am

So what is rebound anyway. It is talked about a lot in ski reviews etc but what is it really?
Is it the bent ski that stores energy that is returned at the end of the turn? I think this is the common understanding.
However, if we look a bit more carefully I think this is a small part of the rebound. If I take my race stock SLs I can easily bend them by hand more than they are bent when tipping them 70 degrees on a hard surface. This level of energy is not enough to launch a body, or even give a significant kick.
But when I ski the feeling is definitely that they kick back a lot. I believe that this is more related to the decreased angle between the gravity and the centripetal force after the fall line. This will increase the pressure both direcly and indirectly, and it also causes a vaulting effect. It will feel like the skis are kicking back. It can make you airborne if the forces are not managed. The gravity is what it is so the thing affecting the amount of kickback is the centripetal force, which in turn is determined by the turn radius of the CoG.
This is why different skis have more or less rebound. A tight turn radius ski with torsional stiffness and great edge grip, like a SL race ski, will have a significantly more aggressive rebound. To make things more difficult they are also soft and short in the tail, thus making fore-aft very important.

I have two pair of free-ride volks which are much stiffer than my race-stocks, but they have a lot less rebound.
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Re: Rebound

Postby Max_501 » Thu Jun 16, 2011 10:11 am

When skiing on my race stock GS skis I get a large amount of rebound. And when I mistime the release I get launched and end up crashing.
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Re: Rebound

Postby HighAngles » Thu Jun 16, 2011 11:15 am

What you're feeling could also likely be attributed to binding mount position variables. Stocklis are notorious for having fairly rearward factory marks. Compare the mount positions between these two skis and please comment.
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Re: Rebound

Postby Kiwi » Thu Jun 16, 2011 2:49 pm

The turns were made indoors on snow in much the same spot. The slope was consistent and turn size, speed and shape was much the same. They were both slalom skis a few mls different in length. Doesn't that mean the difference is either the ski or my position on or over the ski. I do not think I was back on the ski on that slope. The turns were tight and clean.

I'm not dissatisfied with Stockli, great ski. The Laser SC is a great piste ski I think, firm but forgiving. It skies closer to the SS in terms of work. The Stocki FIS slalom ski needs much more work at normal speed for me. I was really surprised and very impressed by the SS. It seemed to draw through the turn almost on its own. Its now obvious why HH likes this ski along with the rest of the PMTS aficionados.

I think there is a lot to be said about a ski with less work and more time for precision and learning for me. Diana did a post about skis for masters racers along this line.

Obviously I have a lot more dollars to get out of the Stockli.

High Angles, I'll compare the binding positions on the skis and get back to you. I'm sure the Stockli was centre of boot on centre mark but I'll check the mark on the running surface for comparison.

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Re: Rebound

Postby Max_501 » Thu Jun 16, 2011 5:41 pm

I suppose you could be feeling the difference in the way the tails release. The SS tail has more shape so it doesn't release as easily and that might be described as causing more rebound (although that's not how I think of it).
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Re: Rebound

Postby dan.boisvert » Thu Jun 16, 2011 6:40 pm

Kiwi wrote:The Stocki FIS slalom ski needs much more work at normal speed for me.


Any chance your normal speed is below the intended working speed of the ski? If your speed was below that range, I can see how it could feel damp but dead. Going faster might wake it up.
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Re: Rebound

Postby Kiwi » Fri Jun 17, 2011 7:44 pm

I think the changing from the Stocki to SS while skiing indoors made me a aware of rebound a lot more than before. I put that down to skiing indoors at slower speed where the SS was still giving great feedback but the Stocki wasn't — because it was indoors and too slow for that ski or more probably because I do not have the skill to extract the performance.

Changing skis like I did gave me insight, here's hoping, into something I think HH addresses but I've not fully appreciated before-rebound.

The SS seems to be a ski that allowed me to extract some rebound at that speed with my skill level. I'm going to try and develop this cue on the Stockli, startlng with a softer ski for indoor. I'll try and build more pressure through tipping more and greater CB before the release. Timing also as Max501 said. If I can't I'll buy some SSs.

Not flexing the inside leg enough through the turn (Essentials pg 102) and Insufficient counterbalance( Essentials 170-171) are what I will work on to improve tipping and get more pressure for the release to get more energy through transition.

The experience says a lot about using the right ski for my skill and the speed of learning; not to mention HH's recommendation of SS as a ski for training on. Reminds me of the expression, You can lead a horse to water but you can't hold its head under.

Kiwi

PS Still no snow in NZ.
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Re: Rebound

Postby BigE » Thu Jun 23, 2011 7:45 pm

Are the tails of the ss softer?
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Re: Rebound

Postby Kiwi » Sat Jun 25, 2011 4:58 pm

I was able to reproduce the feeling of the SSs with the Stockli. The turns were the same as previously, tight carved slalom turns.

It required a lot of dynamic two footed pull back at the end of each turn through transition. At slower speed this felt exaggerated but if not done the rebound was lost. There was a lot of energy in this movement at low speed compared to when moving slightly faster. The release was at the normal speed needed for the turn, fast, but I didn't exaggerate the release.

I found I needed to hold my counter through the release—this is something I now do in my skiing.

The effect of this was a quicker movement across the skis. I felt gently pushed diagonally down the slope, very smooth. I think there was quicker edge engagement but interestingly it felt that I had more time in the high C.

The rebound was like at rhythm for each of the turns, metaphors that come to mind are "heart beat" or "pump". I think the sweet spot of the ski was working to produce this.

Just before writing this I read an excellent thread on the forum from 1997 on rebound and could totally appreciate what was being explained. Pays to do a search before blathering on. The only thing I now wonder about is the force that a GS ski produces when it flings people into the air compared to rebound on slalom skis. The force would seem to be related but can it really be vertically directed rebound?

BigE

I have a confession to make. I have never understood tail flex or tail release. When I see people in shops flexing skis I just nod, means nothing to me.

I appreciate the difference between soft and hard skis when I ski. I concentrate on the ski forward of the bindings and if I feel the tail, I am too far back and I get forward as quickly as possible. The stockli ski is firmer than the SSs but this doesn't seem too effect the force produced, which isn't the general thinking, but I believe a softer ski could make it easier to attain rebound at slower speed providing the ski is quality.

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