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Tuning (gasp!) Straight Skis...

post #1 of 25
Thread Starter 
Ok, I'm goin' for a retro day...Talking 205cm Slalom skis here, Volkl P 20's.
So from last I remember, one had to "detune" the tips and tails of straight skis. Frankly, this should've been a clue that something was wrong with the design....

Now, are we talking hard gummi stone detune or something a little heavier? I know there's still butchers around that use a file on shaped ski "detuning", and I presume that was bad practice even for a straight ski..

Does anyone bother to.....  stonegrind them?
post #2 of 25

I'm reading the Mahres' book No Hill Too Fast and just finished the section on tuning at lunch today.

The bases would get a treatment with sandpaper, anywhere from 80 to 150 grit, wrapped around a file to make the bases flat. They wanted the sandpaper texture to open the pores of the ski so it would accept wax better. They used plastic steel wool to finish up after scraping wax. They would use a stone to detune. They detuned about 18" at the tip and 12" at the tail. They didn't talk about bevels, but I think it was 0 and 90, although it was all done without guides or measuring tools, so it was rough. They aimed for a smooth, burr free edge.

It is pretty cool what you can learn reading the former greats books. I read Killy's Situation Skiing this summer. It has more application today than the extreme movements that the Mahres were presenting, although, both were accurate to how they ski and there is no denying that the Mahres ruled in their day.

 

post #3 of 25
I had a pair of the P20 Sl (and the GS).  Still lying in the loft back in the uk!.  While at one time I used to detune tip and tail a bit I think latterly I h=just eased off teh pressure on the edge file as you got to the last 12 inches at either end.  Also (and I will probably be corrected here) I think it was only on the outside edge i did this, the inside edge got the full treatment 
post #4 of 25
Quote:
Originally Posted by Tog View Post

Frankly, this should've been a clue that something was wrong with the design....

If we look at it from a philosophy of function standpoint, there is _no_ difference between detuning the front of a straight ski and putting reverse camber/rocker in a funshape ski.

Detuning the front of a straight ski gets you surface area, running length, yaw plane stability, all with a shorter effective edge.

Putting rocker in a funshape gets you surface area, running length, yaw plane stability, all with a shorter effective edge.

The song remains the same.
post #5 of 25
Quote:
Originally Posted by comprex View Post
The song remains the same.

Except float in mank.

Quote:
Originally Posted by Tog View Post

Ok, I'm goin' for a retro day...Talking 205cm Slalom skis here, Volkl P 20's.
So from last I remember, one had to "detune" the tips and tails of straight skis. Frankly, this should've been a clue that something was wrong with the design....

Now, are we talking hard gummi stone detune or something a little heavier? I know there's still butchers around that use a file on shaped ski "detuning", and I presume that was bad practice even for a straight ski..

Does anyone bother to.....  stonegrind them?

I keep looking at my 210 SMs and think of hiting the base with the SkiVisions planer, sharpening the edges, 0:0 and do the ole stone on 3" or so of the tips and tails. After some mileage, start messing with one pair of edges just to see how they compare. The non-starter is the bindings.....

I think you should make them razor sharp and wax 'em. Take them out with a stone in your pocket, get them up to 90 and crank turns. If you catch an edge and create a yard sale, dull the tips and tails a little. Repeat until no more yard sale. Shoot video and report back
post #6 of 25
Quote:
Originally Posted by Alpinord View Post

. The non-starter is the bindings.....
 

I put Railflex plates on 5-6 of my pairs already.
post #7 of 25
The last pair of straight-era GS skis I had were 205cm Squadra Corses.  I ran them with a flat base (no base bevel) and a simple square edge (no acute edge angle).  Detuning was only done on the parts of shovel & tail that were outside of the contact surface.

The last pair of straight-era SL skis I had were 200cm TR4s.  These were run with a flat base and a 2 degree edge angle.  Again, detuning was only done on the parts of the shovel & tail that were outside the contact surface.

Even back with straight skis, detuning, although very common, was not universal.  Leaving the full edge sharp gave a good performance boost, as long as you paid attention to lateral balance.
post #8 of 25
Doug Coombs knows tuning

For many reasons this video by Doug is timeless and may put this discussion into a proper perspective.

Enjoy your retro day Tog. Don't forget to post the pictures.
post #9 of 25
I detune 15% of total length on the tip and 10% length of the tail by VERY lightly dragging a small file at a 45 degree angle using only the weight of the file to take the edge down a tad.
So for a 200 cm I would detune 30 cm of the tip starting just before it flattens out to touch the snow and then 20 cm from the tail up the same way.
post #10 of 25
Thread Starter 
Disagree with the detuning straight skis  = rocker assertion. Rocker is most definitely an advantage in heavy snow.  Remember "sit back"?
Really, if I posted that in a gear forum that people with those skis actually read, the flame throwers would be out in force! That's why I didn't quote you to protect you from...well...maybe a one-click flaming anyway. No ski with a rocker of course needs to be tuned apparently

Quote:
Originally Posted by Alpinord View Post
I think you should make them razor sharp and wax 'em. Take them out with a stone in your pocket, get them up to 90 and crank turns. If you catch an edge and create a yard sale, dull the tips and tails a little. Repeat until no more yard sale. Shoot video and report back
You mean 90 km/h ? or 90 degrees? Well, we know they go straight pretty well...
Quote:
Originally Posted by mogulmuncher View Post

The last pair of straight-era GS skis I had were 205cm Squadra Corses.  I ran them with a flat base (no base bevel) and a simple square edge (no acute edge angle).  Detuning was only done on the parts of shovel & tail that were outside of the contact surface.

The last pair of straight-era SL skis I had were 200cm TR4s.  These were run with a flat base and a 2 degree edge angle.  Again, detuning was only done on the parts of the shovel & tail that were outside the contact surface.

Even back with straight skis, detuning, although very common, was not universal.  Leaving the full edge sharp gave a good performance boost, as long as you paid attention to lateral balance.

Ah...forgot to ask about the base bevel! I'll probably run them flat also or maybe a half. Few shops can actually get a flat base anyway.

I knew the SkiVisions planer thing would come out! Well, if I had that Ruby stone I might consider it, but the stoneI have isn't worth much even in the garden for the snails. Plus, I'd love to see the guys face when I bring in the P20's for a stone grind. I think I'll go to the guy who's got the automatic one with the vaccuum hold downs for the skis, and the Lcd readout.

Originally Posted by crgildart View Post

I detune 15% of total length on the tip and 10% length of the tail by VERY lightly dragging a small file at a 45 degree angle using only the weight of the file to take the edge down a tad.
So for a 200 cm I would detune 30 cm of the tip starting just before it flattens out to touch the snow and then 20 cm from the tail up the same way.
30 cm of detuning! Good god man! That's quite the rocker you've got on those boys.
You ski them all the time right?
Question: Why not just ski a shorter ski?
post #11 of 25
Quote:
Originally Posted by Tog View PostQuote:
You mean 90 km/h ? or 90 degrees? Well, we know they go straight pretty well...
 
90 mph and use high speed film for your testing video.
post #12 of 25
Quote:
Originally Posted by Tog View Post

Ok, I'm goin' for a retro day...Talking 205cm Slalom skis here, Volkl P 20's.
So from last I remember, one had to "detune" the tips and tails of straight skis. Frankly, this should've been a clue that something was wrong with the design....

Now, are we talking hard gummi stone detune or something a little heavier? I know there's still butchers around that use a file on shaped ski "detuning", and I presume that was bad practice even for a straight ski..

Does anyone bother to.....  stonegrind them?

Tog....you gotta chill dude! File'm flat, 90 degrees on the side and throw some canning paraffin wax on the snow side 
post #13 of 25
Quote:
Originally Posted by Tog View Post

30 cm of detuning! Good god man! That's quite the rocker you've got on those boys.
You ski them all the time right?
Question: Why not just ski a shorter ski?
 
I haven't skied a straight ski in over a year.  .I'm talking 30 cm from the curve right before it flattens out, not just the running surface. Really closer to 20 when you take out the part that isn't on the snow.
It's really only the part right under your boot and about a foot fore and aft that REALLY matters on a straight ski edge.
post #14 of 25
I've skied a few straight skis nice and sharp with no detuning, old Fischer RC4 Vacuums, Dynastar GS skis, even a few recreational skis (Kästle. "special R" comes to mind).  I remember that special R because I spent so long getting it nice and sharp after finding it at a church yardsale.  I tuned it 0 base, 3 side, taking off a lot of sidewall.  I will admit that the ski didn't want to do anything other than ride like it was on rails, so if pivoting a flat ski is your game, then you might want to detune.  I on the other hand like the feeling that my skis are on rails, and don't mind putting some effort into shaping the ski and getting a little physical to push it out of it's groove if and when needed.

My only straight skis at present are 208 SGs from the early to mid 80's.  I like 'em razor sharp tip to tail. 1/2 a degree base, 2-side;  they work just fine that way.  I would gladly crank them up to 90 and make some turns, but I can't afford a ski holiday, and the biggest hill around home is too small to get up much past 60.  You can generally get up to cruising speed on the steep bit near the top, and then they're good for one good set up turn, a nice transition into a beautiful turn 2, turn a still acceptable turn 3 at an unexciting speed and then it's time to brake to the lift line.  60 is not as exciting as 90, but it's pretty exiting when you're headed 90 degrees from the fall line and the trail isn't too wide; you wouldn't want to botch that 2nd turn.  And there's usually a few mobile SG gates for whom you have to keep adjusting your line that make it interesting too.

Tried 1 base, 2 -side. Didn't like it that way.  A little base bevel makes a ski run faster, too much makes it sloppy.  
post #15 of 25
Base maintenance is the same regardless whether it's a shaped ski or a straight ski.  On my old straight skis I used a 0.5 degree base and 1.5 degree side bevel for GS (210 cm) and went with a flat base and 1 degree side bevel for slalom (207 cm).  Either way, I wanted to achieve an extra 1 degree bite.  That was my preference, anyway.  Too much side edge bevel will make a long straight ski difficult to turn and very grabby.  With a short shaped ski you can get away with pretty big bevels (I use 3 degree side bevel on my current 163 cm slaloms and 0.5 base)

I would 'mildly' detune about 6" of the tip and tail with a fibretex pad or soft stone so that they weren't as razor sharp as the rest of the edge, but were still sharp.
post #16 of 25
Thread Starter 
Thanks for the replies. Interesting on the bases. The shop tech where I took them, who has been around for a long time, said "no one skied a flat base bevel straight ski. Not even the world cup guys." He was pretty adamant that no one skied straights less than one degree.  I was pretty sure he was wrong then, and now I know he was wrong.
Such misconceptions drive me crazy.

He was right about one thing though. Everyone hand filing bases with tape wrapped around the files, and frequently filing the bases, probably gave them multiple degrees of base bevel.
post #17 of 25

Tog..I've got a tuning brochure put out by Olin skis back in the 70's.
I'll try and get a scan or two for ya to feast your eyes upon 

 

post #18 of 25
Quote:
Originally Posted by Tog View Post

Thanks for the replies. Interesting on the bases. The shop tech where I took them, who has been around for a long time, said "no one skied a flat base bevel straight ski. Not even the world cup guys." He was pretty adamant that no one skied straights less than one degree. 
He's completely wrong.  Straight skis were always skied completely flat (no base bevel) up until maybe 10 years (approx) before the advent of shaped skis.  It was around that time that technicians on the world cup started playing with different combinations of base and side beveling (base beveling tools and machines didn't even exist then, and we would simply wrap tape around a file to tip the file and create a base bevel angle).  It trickled down to non-WC racers, in general, and later on became the common way to tune skis once machines became available at shops that could accurately bevel the base.

I'm a bit sketchy on exact time frames when base and side edge bevels on race skis became common place (it was a long time ago), but by the time it became common for the general public, straight skis were pretty much gone (or almost gone) from the market place.  So basically the technician you talked to was wrong.  Although racers in the know were beveling the base edges on their straight skis (doing it themselves with adapted tools), most straight skis were still being tuned without a base bevel because shops didn't have the equipment to do it, and by the time they did the straight ski had disappeared from the market.
post #19 of 25
 Oh James, you have a retro angel looking out for you....





Edited by Trekchick - 12/8/09 at 7:08am
post #20 of 25
Also, take a look at the KUUSport website.  There's a section dedicated to modern tuning technique, with a downloadable pdf manual and video (free downloads).
http://www.kuu.com/how2tune.htm
post #21 of 25
The  Olin ski tuning pamphlet was from the early 70's so it's real old school tuning at it's very "best"

post #22 of 25

The Olin Care and Maintenance brochure was the best of its kind and even now, most of it still applies.  It was very well written and easy to understand for both the newbie and the accomplished tuner.  It was rewritten in the 80's. The newer version had a few updates based on newer tools and techniques that had come into being by that time.  Straight skis were beveled on the base, but it was done mostly by feel (or wraps of tape as described above).  Not very precise, but it did allow torsionally stiff straight skis to be coaxed into a turn a bit easier. 

post #23 of 25

Straight skis were not base beveled. They were skied 0/0. We called it FLAT FILING!!!! REMEMBER?????................................

 

At least throguh the 60's, 70's and most of the 80's.and early 90's.   Elan SCX in about 1993/94 The K2 Four was introduced in 1995. there were some increased sidecut race skis before this that the Mahres and Ingemar Stenmark were screwing around with but these were still full length skis.

 

When they really increased the shape and left the ski full length it skied like a tank. so they began to shorten.

 

Used to lay my skis on the steps of the lodge and file 'em flat with a 12" mill bastard file!

 

As the Olin brochure shows 3" detune and only beyond contact.

 

Some of us could actually carve a straight ski back then! th_dunno-1[1].gif

post #24 of 25

My SL skis were razor sharp - contact to contact. 0 base, 3 degree edge. For GS I backed off to a 1 degree edge. I knew guys who did what they call a "variable bevel", but I liked my skis very hooky.

post #25 of 25
Quote:
Originally Posted by Rossi Smash View Post



Tog....you gotta chill dude! File'm flat, 90 degrees on the side and throw some canning paraffin wax on the snow side 


Odd fact:  Gulf wax is harder than CH8.   

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