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-   -   Skis - race tune (http://www.hkssa.net/showthread.php?t=34805)

Mike 2010-02-12 20:20

Skis - race tune
 
引用:

作者: stillskiing (文章 44757)
One should try a race tune. The ski WILL COME ALIVE.....But that is another topic.

Stillskiing - would you like to do that? :) I mean to start a new topic on "race tune".

skier 2010-02-12 21:00

引用:

作者: stillskiing (文章 44757)
....... One should try a race tune. The ski WILL COME ALIVE.....But that is another topic.


Does a race tune also mean more acute angles ?

For the benefit of HKSSA members, I will bring this to their attention:
Years back, all ski edges are 90 degrees and 0, 0 -- meaning that the base to the steel edges are flush, and the steel edge goes 'straight up' making the edge 90 degrees.

Now all stock skis have some kind of bevel. e.g. 1, 1 meaning that when the base go to the steel edge, the base bevel is one degree slanted up. But the wall of the steel edge also slanted in one degree (edge bevel) making it still 90 degrees -- the reason that it is 1, 1 is so that it (with the base bevel of 1 instead of 0) will not catch an edge unwantedly (too reactive) -- it is good to roll to engage an edge.

Now different stock skis have different bevels as standards, eg:

Atomic 1, 3
K2 0.5, 1
Volkl 1, 2

Racers tune their ski according to what they think the course condition of the day of the race will be, and to their individul's liking. So it could be 2, 5 to handle icy condition in a Super GS event.

If it is that extreme, we mortals won't be able to handle it.


Here is an article on base bevel:

http://www.snocountry.com/index.php/...ase-bevel.html

Another good article on Edge Angles and Sidewalls:

http://www.edgewiseskitunes.com/arti...ml?ref=11&sp=4

Mike 2010-02-13 11:54

Tuning a pair of skis whether for recreational use or for racing purpose, the basic procedure is similar. It is the way how to prepare the base and the usage of material that makes the difference.

For tuning a pair of skis for recreational use, you will want the skis to be suitable for most condition and different terrain. You also want the skis to be tuned in such a way that the user can handle them.

For race tuning, the skis have to be tuned to suit a particular skier, the discipline he competes in, the condition of the course at the time of competition - ie. it is very specific.

Tuning the skis for racing is not just about the base bevel angle and edge bevel angle.
The structure of the base also makes a big difference. Structure helps to break up the water suction and opens up the base so it will accept wax more easily. You heard about linear structure and cross-hatch structure, it is also noted that a lot of the speed skis have a cross-hatch pattern. You might also have heard of medium or fine linear structure or a coarse structure. Coarse structure is real aggressive and can make the ski hard to turn which is why it is used mostly for downhill or speed skis and wet snow.

Wax also makes a big difference as well, different wax for different snow conditions. Wax additives such as "speedpaste" or "speedpowder" can make the skis glide a lot faster, but these additives do not last long and are very expensive.
Hence, the skis have to be prepared in such a way that they are 100% fit for the skiers and the course at the time of competition.

Stillskiing & Skier - anything to add or comment?

skier 2010-02-13 21:27

Absolutely, tuning and waxing for racing is a Science as well as an art like cooking -- you may have the recipe but the result may not taste good.

Top WC racers all have special technicians that do the tuning and waxing, with secret wax formula and tuning secret/subtlety. Skiing technique has to be complimented by the right tuning and the wax -- after all, just the wax alone can make a big difference when one second difference can mean a medal vs. none.

But for us recreational skiers, all we need to make sure is that we have a good ironed-in wax for a pair of new skis. And then you can replenish it with hot wax or even spray wax every few days of skiing so it will glide well.

Tune the edges if it gets dull from skiing icy conditions for many days. We do not need to be so finicky. Pay more attention to improving techniques instead of worrying too much on tuning side of things -- yes, base need to be flat, edges need to be relatively sharp and need to have wax for better glide, and that is all.:)

Mike 2010-02-14 21:53

I mentioned "structure" above. So, what really does that mean?

It is all about the little grooves on the bottom of the skis. Structuring is the practice of creating a series of very small, parallel grooves on the entire surface of the ski bases.
The purpose of structuring is to make sure that the theoretically proper amount of water is created between ski and snow as you glide. Whether or not this is actually the mechanics involved is subject to much discussions.

Structure needs to be small grooves when snow temperatures are cold, and they need to be bigger when snow temperature starts to warm up.

In cold, dry snow you want to increase the amount of water present between the ski and snow for maximum glide. You do this by increasing the friction between the ski base and the snow. By increasing the volume of base that touches the snow, you increase friction. So, you want to have lots of grooves. The more, the better. To increase the number of grooves, they have to be small.

In warm, wet snow you have the reverse problem. Too much friction creates too much water which sucks your skis to the snow, makes them feel "sticky." Now you need coarser structure.

After you structure the ski base, you need to wax them. Wax naturally fills in all the grooves. So you you need to use a stiff brush after waxing because you want to get the wax out of the grooves, in other words, it should "coat" the grooves, not fill them in.

Mike 2010-02-15 17:24

So what about the edge angles that "Skier" mentioned in his earlier posting above.

A lot of studies were carried out by different manufacturers, organisations, national team, racers etc. on what different edge angles will do to the behaviour of the skis. One such study came out with the following finding:

The test was to actually ski on different edge angles to see if one could feel how the ski changed when different base and side edge angles were ground into the ski.

They started with two identical racing skis mounted with two identical bindings. For their first test they varied just the base edge. They tuned Ski "A" to 1º base edge and 2º side edge. The Ski "B" was 1/2º base and 2º side. They could clearly feel how much quicker Ski "B" was to start the turn and how much less angulation it took to hold. They also learned that a 1º base edge angle was more forgiving for less aggressive skiers.

For the second part of the test they tuned the base edges of both skis at 1/2º. Ski "A" had a 2º side edge angle and Ski "B" was tuned with a 3º side edge. In normal free skiing they found that it was difficult to feel much difference between the two side edges. However, when they really laid the ski over and ripped (like running gates in a slalom course) the 3º side edge held much better. They find that most recreational skiers prefer a 2º side edge, racers a 3º. An exception to this would be young, lower level junior racers. 3º side edges are more demanding to ski on. They are unforgiving in that they won't slide or skid which can be harmful to the knee. Many coaches recommend that younger skiers use a 2º side edge.

skier 2010-02-15 17:56

To augment what Mike said, the following is an excerpt from the link I gave above:

The flatter the bevel, the quicker the ski’s edge will engage. As you start to give the ski more bevel, the ski begins to need more angle before it engages, thus making it a slower reaction. This has the same effect as canting. If you cant the boots to the outside, you get a faster reaction and to the inside, a slower reaction. Under these rules, it is also true that base bevel changes for different events. In slalom, we want a very quick reaction, in GS a little less and in DH, the skis need to be very subtle with edge engagement.

Mike 2010-06-16 16:55

http://www.youtube.com/watch?v=2Upsd...eature=related

http://www.youtube.com/watch?v=93cwi...eature=related

Mike 2010-09-01 17:25

Very interesting discussion between a WC racer and his ski technican on ski preparation :

http://www.youtube.com/watch?v=PW_Tvx6cUY8

Mike 2010-09-01 17:51

引用:

作者: Mike (文章 56203)
Very interesting discussion between a WC racer and his ski technican on ski preparation :

As a matter of interest, the hand held machine that the technican is using in the video is a "Trione", which is the most used device in the WC circuit. It costs about 1,200 Euros each.

Another brand that is equally popular with the American is "Snow Glide"
( http://www.snowglidetools.com/snow.glide.tools.html ).

One word of caution is the danger to your health using these machines - they put off a very fine cloud of metal dust that can be breathed into your lungs. There has been a few WC technicans that have experienced issues with this dust getting into their lungs. Eye protection and a respirator is mandatory. Also prefer to have some type of magnets on the tool or on the edge of your bench below your vice to pull the dust out of the air.

Also, note that there are still many WC technicans (especially in SG and Downhill) that still use hand files. For an individual racer, doing only your own skis, you will find that by the time you set up the machine, you could have touched up your skis with a file.

Mike 2011-04-06 21:29

If anyone thinks that a 3 degree side edge dulls quicker then a 1 or 2 degree, it is not the case, certainly not with the skis of nowadays. The edge angle isn't going to change either, ie. not going to change from a 3 degree to a 2 degree, but the edge is getting progressively rounder the more it is skied on (that is without being re-sharpened).

Having said that, the base bevel does increase with skiing. The constant abrasion of the snow and ice on the base edge rubs steel edge material away and increases the base bevel.

Mike 2011-04-07 07:09

引用:

作者: snowrider (文章 74897)
I don't know if that is the case, but all the racers that I know in my local area tune skis themsleves. Also 99% instructors that I know tune skis themselves.

Of course I tune my skis/board myself too. Why? It's not about saving money, but it's about that nobody knows how I feel about my skis on my feet except myself.

I think both of you are correct. I was talking to an ex-WC racers in Switzerland few years ago, he tuned his own skis everyday and he told me that he had a full supporting team to tune his skis when he was racing on the WC circuit. Local racers might not have the same back-up as those WC racers.

As a matter of interest, what angles do you set your skis at?

skier 2011-04-07 11:19

引用:

作者: snowrider (文章 74904)
I tune my skis pretty much the standard:
1-degree beveler for the base
2-degree beveler for side

But I sharpen them almost after every ski days (because of the eastern icy cement dull the edge very quick) with diamond stone. I use file to sharpen around every 5 ski days or if the edges hit some rock. When I use file, I then also do base repairment and wax.

Do you not use a preset tool so that the 1-degree base and 2-degree side bevel is correct and constant all the way through?

Mckay 2011-04-07 12:54

引用:

作者: snowrider (文章 74905)
BTW, I keep my skis very sharp (as sharp as a knife) so that you can use them to cut paper, in order to keep good condition for skiing on ice.

I don't know why it's hard to tune old skis sharp and ir's very easy to tune them sharp when they are new. I like the edges to be sharp.

Mckay 2011-04-07 12:56

引用:

作者: skier (文章 74908)
Do you not use a preset tool so that the 1-degree base and 2-degree side bevel is correct and constant all the way through?

I don't have much knowledge about ski tuning but just like sharp edges. So i like new skis.


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