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Whatever happened to grooves in ski bases?

post #1 of 25
Thread Starter 

Back in the day, skis had a groove running down the middle of their bases lengthwise. I always surmised that this was to facillitate straight line tracking. First they were rounded, and then they became squared off and shallower. Then they disappeared altogether, I assume replaced by base structure. Anyway, I'm curious about this evolution. What were they for, and why were they discontinued? 

post #2 of 25

Pretty sure they were so the skis would track straight, which in retrospect doesn't make a lot of sense since those old skis were hard enough to turn as it is. Base structure is different--its purpose is to make the ski-snow interface faster by breaking up the suction created by the thin layer of water between the two. 

post #3 of 25
Thread Starter 

Thanks. Yes, that makes more sense. Jumping skis used to have 3 grooves, if I remember correctly. Do World Cup DH skis still have a groove? I doubt it.

post #4 of 25
Quote:
Originally Posted by Tominator View Post

. Do World Cup DH skis still have a groove? I doubt it.

No. They don't.
post #5 of 25

A XC racing skis have a groove, some have several.  We have experimented with adding two more grooves to the tail of some skis, and the improvement in flat ski tracking can be dramatic.  I'm sure it slows the glide some.

post #6 of 25
Quote:
Originally Posted by Tominator View Post
 

and why were they discontinued? 

 

The advent of sintered bases meant that grooves had to be milled or cut instead of moulded directly - so they became more expensive for a given provable (read: marketable) benefit to the skier.
 

The advent of torsonally stiff skis and big sidecuts meant that people were riding their edges more - so the net provable (read: marketable) benefit to skiers got insignificant.  

 

Quote:
Originally Posted by oldgoat View Post
 

Pretty sure they were so the skis would track straight, which in retrospect doesn't make a lot of sense since those old skis were hard enough to turn as it is.

 

It doesn't make sense because it's an incomplete picture.

 

An old *stiff* ski was hard to turn because it was stiff.   If the skier was able to completely decamber the ski  with only 1/2 body weight on the ski, then the groove wasn't really necessary because the ski would track by itself.           But if 1/2 body weight *doesn't* fully decamber the ski then the ski can't really track straight because it's not engaging the snow along its full length.  

How many times have you seen skiers buy old school straight 'race' skis because 'if it's good for racers it must be good for me'  and then only be able to ride the tails?   Yeh, the groove made tracking easier for people who did that.


An old soft ski was hard to turn because it was soft and the edges far out from the boot were hard to keep in proper engagement with the snow during turns.     It was also soft enough to bend into full reverse camber under the boot with 1/2 body weight or less - which meant you got the greasy underfoot feel of today's full-rocker skis without being able to trust the edges like you can on today's gear.     So the groove at least got rid of that greasy underfoot feel - when the snow was loose enough to play nice.

 

post #7 of 25

I don't think a modern ski would react well with a groove.  The bigger the side cut the more squirrelly the ski is when running flat,  These days the less time you spend on a flat ski the better your skiing experience tends to be.  Back in the 60s and earlier some followed a philosophy that the more time spent on a flat ski the faster the run would be.. so we had quick edge sets and longer straight runs between.  That changed to carving turns as the favored path to success in the 70s and 80s. 

 

Good question about downhill skis as that is the only remaining race discipline where a groove might still be helpful.  I see the cost and design problem tuna mentioned as the main reason that isn't still done.

 

Also, park skis might benefit some from a groove to help tracking straight towards the jumps and up the ramp.. But, most still do a quick edge set on the pop to start the spins.  Regardless, I'd like a groove under men while heading at the jump.  But, I don't want to pay 40% more for the ski to get that..

post #8 of 25
Quote:
Originally Posted by crgildart View Post
 

Good question about downhill skis as that is the only remaining race discipline where a groove might still be helpful.  I see the cost and design problem tuna mentioned as the main reason that isn't still done.

If you watch WC DH races, you'll see that the competitors have no problem with tracking -- what they're really looking for is glide speed.  This is probably why we don't see DH skis with grooves in them.   And for skis used on the WC, cost would not be a barrier.

post #9 of 25
Quote:
Originally Posted by chemist View Post
 

If you watch WC DH races, you'll see that the competitors have no problem with tracking -- what they're really looking for is glide speed.  This is probably why we don't see DH skis with grooves in them.   And for skis used on the WC, cost would not be a barrier.


They may have some pretty well laid structure that works in the same way one center groove was intended to.  That would enhance glide speed and straight tracking on a flat ski.

post #10 of 25
Thankfully I am still in the groove.
post #11 of 25
Quote:
Originally Posted by crgildart View Post
 


They may have some pretty well laid structure that works in the same way one center groove was intended to.  That would enhance glide speed and straight tracking on a flat ski.

I don't know if structure would have any effect on tracking.  

 

I do recall one ex-WC downhiller mentioning that the key to gliding was to keep the skis perfectly flat, and you could detect when you'd found that sweet spot when the skis acquired a "swimming" feeling. The fact that they seek out that swimming feeling suggests that they have no problems with tracking.

post #12 of 25
Quote:
Originally Posted by chemist View Post
 

I don't know if structure would have any effect on tracking.  

 

I do recall one ex-WC downhiller mentioning that the key to gliding was to keep the skis perfectly flat, and you could detect when you'd found that sweet spot when the skis acquired a "swimming" feeling. The fact that they seek out that swimming feeling suggests that they have no problems with tracking.

 

 

Bingo.  If a ski has a groove it is likely much more difficult to determine if the ski is flat since the groove resists 'squirrly' 'swimming'.    On a WC DH course there is very little loose snow these days.  Most of us would call it pure ice.  I don't suppose a groove does anything on 'ice' but can certainly see it being a detriment to speed when the groove fills to any degree.  

 

I have skied the Birds of Prey runs a week or so after the races...nearly impossible to ski with any sort of rhythm, even on well tuned skis.  Like trying to etch your initials in a granite wall with your fingernails.

post #13 of 25

The groove helped with straight line running, but did not interfere with turning, because the skis were tipped to turn.  Probably would still track better with the groove, but DH racers can put up with the lack of groove in exchange for faster gliding, imho.

 

BTW If anybody knows where I can get a scraper that still has a profile to scrape the wax out of my centre groove, please let me know.IMG_0773.jpg

post #14 of 25
How about buying a plastic putty knife of appropriate width at Home Depot and cutting the top to mate it with your ski bottom/groove.
Edited by jc-ski - 2/10/15 at 5:18pm
post #15 of 25
post #16 of 25
Quote:
Originally Posted by Ghost View Post
 

 

 

BTW If anybody knows where I can get a scraper that still has a profile to scrape the wax out of my centre groove, please let me know.

Copyright 2009 Backcountry.com

http://www.backcountry.com/swix-groove-all-purpose-scraper?ti=UExQIEJyYW5kOkNyb3NzIENvdW50cnkgU2tpaW5nOjE6NzoxMDAwMDAwNzBfYmNzQ2F0NTEwMDAwNTU&skid=SWI0091-OC-OS

post #17 of 25

^^^^^^close.

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

The groove helped with straight line running, but did not interfere with turning, because the skis were tipped to turn.  Probably would still track better with the groove, but DH racers can put up with the lack of groove in exchange for faster gliding, imho.

 

BTW If anybody knows where I can get a scraper that still has a profile to scrape the wax out of my centre groove, please let me know.

I make my own from scrap pieces of hard wood, pvc pipe or the edges of wax scrapers.  then I always finish with  my fingernails to get the last little bits.  yes wax gets under your nails but it makes them ooh so much faster;)

 

Royal

post #19 of 25

Sand the corner of a plastic scraper at a 45 degree angle just far enough to fit your groove.  The plastic and metal scrapers used to come with one corner notched like that.

post #20 of 25
Quote:
Originally Posted by crgildart View Post


They may have some pretty well laid structure that works in the same way one center groove was intended to.  That would enhance glide speed and straight tracking on a flat ski.

 


It was for release of snow and water under the ski, or so I have been told, and structure has taken it's place.
post #21 of 25
^^^

Well, newfydog is correct in saying that xc skis still have the groove, as well as structure, obviously. So it must do something useful in that context.
post #22 of 25
When ever I put deep structure into a ski.....I frequently rill my xc skis for spring snow....,there is a dramatic improvement in straight line tracking. Sometimes on the morning corn snow a rilled ski tracks so strongly it almost trips you skating. The rills lose their sharpness in a few kms. and the effect fades somewhat, but structure can definitely act like a groove.
post #23 of 25
Quote:
Originally Posted by newfydog View Post

When ever I put deep structure into a ski.....I frequently rill my xc skis for spring snow....,there is a dramatic improvement in straight line tracking. Sometimes on the morning corn snow a rilled ski tracks so strongly it almost trips you skating. The rills lose their sharpness in a few kms. and the effect fades somewhat, but structure can definitely act like a groove.


Yep, there are at least a half dozen threads on this forum where some skier was complaining that the tuning job ruined their skis so they don't turn easily anymore.  Almost always turns out to be the structure if it wasn't a hanging burr causing it.

post #24 of 25
Quote:
Originally Posted by qcanoe View Post

^^^

Well, newfydog is correct in saying that xc skis still have the groove, as well as structure, obviously. So it must do something useful in that context.

 

You will perceive that xc skis are specifically chosen to *not* decamber under 1/2 body weight of the skier, and therefore the situation is analogous to that for straight alpine skis that are too stiff for the skier. 

post #25 of 25
Quote:
Originally Posted by Ghost View Post
 

 

BTW If anybody knows where I can get a scraper that still has a profile to scrape the wax out of my centre groove, please let me know.

Or you could just leave the wax in the groove, which some racers were doing at the end of the groove era, because they felt it created faster gliding:

 

https://books.google.com/books?id=G6L3XAwFbI0C&pg=PA97&lpg=PA97&dq=why+do+skis+have+grooves?&source=bl&ots=nd5VUbnyRe&sig=mUQWlekJFiitBlnRb8OWWFr8ch8&hl=en&sa=X&ei=sprbVPbzAYaKyASI2YCYDA&ved=0CEMQ6AEwCA#v=onepage&q=why%20do%20skis%20have%20grooves%3F&f=false

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