Race skis selected at the factory

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Cloxxki
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Race skis selected at the factory

Postby Cloxxki » Tue Dec 04, 2007 4:24 am

Please enlighten me on this.
I read how at the factory, dozens or hundreds of skis are selected to be used by sponsored athletes.
Now I understand the basics about flex and skier's weight, but how can a ski be lab-tested to be faster than others? What are factories looking at to make this selection? And, how much of a performance difference is there?

For instance, how much would a properly fitted typical race ski such as Fischer Carbonlites, bought at a shop like we do, hold back a WC podium contender, all wax prep etc being the same?

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Postby Cloxxki » Tue Dec 04, 2007 4:50 am

Alright, I just read this : http://www.caldwellsport.com/ski-servic ... valuation/

I can see how marking skis off the production for these properties (if there's so much variation with all these unnatural materials used). But is there another "good" and "bad" parameter they're looking at?

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Postby Montana » Tue Dec 04, 2007 9:46 am

I'm convinced that there is much more to a fast ski than flex (again given equal wax, ability, etc.). Two pair of skis with equal flex, one with a soft tip the other with a stiff tip will perform differently. The soft tip ski (IMO) would be better in soft snow. The stiff tip ski might run faster on a firm track.

Another thing to look at is what happens to a ski when compressed with full body weight or (in the pushoff) with much more than full body weight. Some skis will flatten nicely and present a uniform force along its entire length while another ski might concentrate the pushoff force in one section of the ski or another.
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donpollari
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Magic skis

Postby donpollari » Tue Dec 04, 2007 6:55 pm

Perhaps this is a myth, but I put some stock in it.

Supposedly:

The sintered p-tex that ski bases are made of is originally produced by putting p-tex fragments under tremendous heat and pressure. This produces a big block of "sintered" p-tex. Ski base material is peeled from this large chunk on a big lathe.

Now, when you think about that original huge chunk of p-tex you can imagine that when it was formed at different depths inside of it the p-tex experienced different heat and pressures - in effect - the p-tex is not completely homogenous.

NOw, from that you could conclude that p-tex from different points within the original block would have different physical properties. NOW, from that, you might conclude that physical properties such as the p-tex's ability to absorb and hold wax may vary.

If this is so, shouldn't there be a area in the block where the pressures and temperatures are supremely optimum in producing p-tex that absorbs and holds glide wax superlatively?

To jump the conclusion - those magic skis you sometimes hear about?:

Those are the skis that just happened to get the p-tex from the magic area of the original block. (Those magic skis also happen to have proper flex characteristics and get a good grind and care).


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Postby matt aro » Wed Dec 05, 2007 12:08 pm

Montana wrote:Another thing to look at is what happens to a ski when compressed with full body weight or (in the pushoff) with much more than full body weight. Some skis will flatten nicely and present a uniform force along its entire length while another ski might concentrate the pushoff force in one section of the ski or another.


As I understand it, and just as you described, the pressure distribution of the ski is a HUGE component of ski fit and speed. Proper 'flex' is not the only factor.

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Postby Cloxxki » Wed Dec 05, 2007 1:32 pm

Such an invisible factor that determins speed...

In Austria last March, my too soft rental skis were flying. I glided down tracks faster than anyone else. Now in November in Switzerland, my "nicer" own Atomic skis, professionally waxed, which really felt better skating, would come to a halt in a matter of meters after I quit skating them... True, people around me were working hard too, but I sure had a trouble keeping up with folks. In March I was giving my instructor a run for his money, November I was chasing little girls and elderly ladies, and losing ground.

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Magic skis cont..

Postby donpollari » Wed Dec 05, 2007 3:03 pm

I was reading a bit more on a p-tex suppliers website.

The density of p-tex is a function of it's molecular weight. Lower density (specific gravity) p-tex is made of longer chain carbon molecules. This low density p-tex is softer/more spongelike and absorbs and holds wax longer. It's also more expensive. Manufacturers can also introduce additives into it.

Besides magic skis everyone has probably heard of particularly lousy skis someone may have owned. Like there's mysteriously optimum p-tex there's also mysteriously lousy p-tex floating around out there. I had a pair of Kastles that were absolute pigs, couldn't get them to glide no matter what. When I finally got a new pair of skis the difference was amazing.

When you find a fast pair of skis, hang on to them - the best skiers in the world are often racing World Cups on skis that are several to many years old:

Devon Kershaw on some old RCS's last weekend in Kuusamo:

[img]http://www.teamtoday.org/Portals/21/images/upload/winter%2007%2008/dist%20D%20Kershaw%20kus%[/img]

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Re: Magic skis cont..

Postby Cloxxki » Wed Dec 05, 2007 3:19 pm

donpollari wrote:I was reading a bit more on a p-tex suppliers website.

The density of p-tex is a function of it's molecular weight. Lower density (specific gravity) p-tex is made of longer chain carbon molecules. This low density p-tex is softer/more spongelike and absorbs and holds wax longer. It's also more expensive. Manufacturers can also introduce additives into it.

Besides magic skis everyone has probably heard of particularly lousy skis someone may have owned. Like there's mysteriously optimum p-tex there's also mysteriously lousy p-tex floating around out there. I had a pair of Kastles that were absolute pigs, couldn't get them to glide no matter what. When I finally got a new pair of skis the difference was amazing.

When you find a fast pair of skis, hang on to them - the best skiers in the world are often racing World Cups on skis that are several to many years old:

Devon Kershaw on some old RCS's last weekend in Kuusamo:

[img]http://www.teamtoday.org/Portals/21/images/upload/winter%2007%2008/dist%20D%20Kershaw%20kus%[/img]

I don't see the pic, but I guess that means that ski speed variance is much greater than a couple years of Austrian brain can improve their average ski quality?

If p-tex quality were such a key factor to gliding speed, wouldn't we be able to buy extra expensive skis with exotic bases?

On a side note, I still can't believe the ski brands don't make longer skate ski's (anymore). The shortest WC ladies run 187's or even 192's, and the strongest men all use 192's. The heavier men are always going to lose out on glide this way, while the ladies are apparently choosing the extra glide over the possible clumsiness of the (up to 25cm longer than themselves) skis. My 192's are 2cms shorter than me. I'm only gliding as fast as my 165cm ladyfriend (on 182's) when the trails point down.
I discussed this at length with a Fisher rep who most certainly knew his skis. It basically came down to racers not asking for it (like in cycling, racers want only what's been proven to work, and all others look at racers to decide on purchases), and the start-up costs for a new length ski molding machine.
And not a custom ski builder on the planet that takes orders for $2000 pairs of skis to spec'd length. Skiers prefer to spend more on their outfit than on their skis, spoiled by mass production of even the very best skis.

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Postby matt aro » Wed Dec 05, 2007 3:46 pm

Hi Don....I hope all is well for you! How's the snow in your neighborhood?

I agree with you in that some skis get 'bad' ptex at the factory. Just like your Kastles, I had a pair of Peltonen Supras that were horrible - I couldn't make them fast for anything. I brought them back to the shop where I bought them and they informed me that Peltonen had used an inferior roll of ptex when making a batch of Supras and mine happened to fall in that batch. Luckily, they swapped them out for a new pair of my choosing.

Take care!

matt

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Fast older race skis

Postby donpollari » Wed Dec 05, 2007 4:18 pm

Sorry the picture's not working. Go here and scroll down to "Kershaw":

http://www.teamtoday.org/Stories/tabid/391/ctl/Details/mid/763/ItemID/1026/Default.aspx

He was skiing extremely fast but faded to 16th at the end of the race on those old Fischer's.

A couple pictures down from him you may also notice Rotchev (4th place) who came in 4th place also on older, but a year or two newer than Kershaw's, Fischer's.

A picture down from him you'll see Svartedal (6th place) on a pair of Atomics that are at least two years old.


Hi Matt, the snow came here last week but it's warmed up. Hear that you're finally getting some early season snow, I've got my fingers crossed for a good Birkie.

Cheers

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Cloxxki
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Re: Fast older race skis

Postby Cloxxki » Wed Dec 05, 2007 5:32 pm

donpollari wrote:Sorry the picture's not working. Go here and scroll down to "Kershaw":

http://www.teamtoday.org/Stories/tabid/391/ctl/Details/mid/763/ItemID/1026/Default.aspx

He was skiing extremely fast but faded to 16th at the end of the race on those old Fischer's.

A couple pictures down from him you may also notice Rotchev (4th place) who came in 4th place also on older, but a year or two newer than Kershaw's, Fischer's.

A picture down from him you'll see Svartedal (6th place) on a pair of Atomics that are at least two years old.



Thanks for pointing those out. Odd not, that all the cumulative flex and wax tech over half a decade or more cannot beat that one old favorite pair of skis.
It would be interesting to see extensive test data on such magic skis compared to current offerings, which also may also show a bit less variance due to newer materials used.

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Postby donpollari » Wed Dec 05, 2007 6:59 pm

From what reading I've been able to come across Zach Caldwell seems to have a good handle on testing and picking fast skis. Way too many variables to make it a science though.

When I worked in a shop we used to paper test new skis with the customer standing on them. What we looked for was the a ski that was stiff enough and had a nice even pressure distribution. Areas of high pressure (hot spots) weren't so good.

Bottom line is you'll the only way of finding a fast ski is to ski on them. When you find them, treasure them.

LOL - you too, can be a "fighting hedgehog". :mrgreen:

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Postby kuan » Thu Dec 06, 2007 6:12 am

Found out last night that I had a really fast pair. :D Fitted by Brian at Gear West. :D

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Postby MN Hoser » Thu Dec 06, 2007 7:47 am

I've had pretty extensive experience with 4000 petex, since I skied for Peltonen a while back. Peltonen was quite sure that 4000 petex (higher molecular weight) was faster than 2000 petex (lower mw and common on most skis) in nearly all conditions. What I've found is that 4000 petex takes a long, long time to get fast. I used to buy downhill lilft tickets and ski on my xc skis to get the kms in them. Once they were good, they were very good, even in cold conditions. Also, the 4000 petex holds it's grind for a long time, even in lots of spring corn snow skiing.

The 2000 petex (on my Fischers) comes up to speed much quicker. The 3000 petex on the cold Fischers is somewhere in between. I've haven't ground my cold pair since I bought them a good five years ago. (They're a great ski for cold snow.) I've heard rumors about cold Fischers being slow, but I think people just don't give the skis time to get fast, so science doesn't matter if the skiers quit buying the product. I think skiers believe the garbage that a ski can be fast in cold snow right after grinding. I think that's only true in certain easy warm snow conditions. Actually, newly ground skis are probably faster in certain warm snow conditions.

Last year I reground a pair of Peltonens (my rock skis), and they definitely got slow. Even after dozens of workouts on these skis, they're still not up to speed, but they're getting there.

I listened to a talk by the Fischer engineer in charge of petex development, and it was interesting. I had a hard time trying to talk about ski-in and base prep ideas since others were also trying to talk with him. The short message is, they do a lot of testing in this area.

Jay

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Postby kuan » Thu Dec 06, 2007 8:30 am

Hey can a skate ski be faster up a hill and slower down? Relatively speaking of course.


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