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How flat is flat enough?

post #1 of 18
Thread Starter 

I just got new skis for my kids -- Dynastar "Team Speed" in 110 for the 7-year-old and 120 for the 9-year-old --  and gave them the once over with a true bar and found that they weren't flat.

 

Here is what the 110s look like (made in Taiwan):

ConvexBase.jpg

 

and here are the 120s (made in France):

ConcaveBase.jpg

 

I'm new to DIY ski tuning and have read a lot about the importance of making sure your bases are flat before doing anything else, but I'm not sure how flat is flat enough.  Is this something I should bring back to the shop?  Or is it no big deal?  Or should we just ski them then decide?

 

If I try to bevel the edges (wanted to try 1/2 for the 9-year-old) is this curvature going to screw up the tune?

 

Any tips or insight will be appreciated!

 

post #2 of 18

Unless you're a proud father of the next Mikaela Shiffrin http://www.youtube.com/watch?v=KmPOT1Imlyk you're over analyzing it.

The 110s, for your 7-year old are definitely not an issue.  Kids at this age are just developing fine motor control that - your kid will outgrow this ski before it becomes an issue.  The 120s for your 9-year could potentially be an issue if they're too railed, and hard to release.  But that only applies if your kid is a strong parallel skier.  It's hard to judge from the picture, because when the light bleeds under the straight edge, it tends to look bigger than it is.  I'd completely ignore anything less than 1/16th of an inch.

 

When you say 1/2 for the 9-year old, I'm assuming 1 degree base, 2 degree side bevel, which I don't think would be an issue.

I hope you're not thinking of a half-degree base bevel.

 

Lastly, since you're based in Seattle, you're mostly skiing in soft, forgiving snow.

post #3 of 18

As stated, probably not a big deal. But they're brand new skis. Why not bring them back to the shop, show them the problem and ask them to give them a very light tune - just enough to flatten the bases. They should be able to do the 1/2 thing too. I'd expect them to do it free of charge, but that's me.

post #4 of 18

The convex ski is an easy fix , just grind them flat by removing the high middle . The concave ski will necessitate the removal of edge metal in order to make them flat and you only have so much metal to work with.. I'd take them back 

 

post #5 of 18

If you are skiing soft snow it won't matter.  If you are on hard snow, the convex skis' edge engagement (first photo) would be problematic and I would grind them flat. 

 

The concave skis are fine if you like to ski with edges engaged, and for me they would work well, but for folks who like to pivot they could cause a problem.

post #6 of 18
Thread Starter 

Thanks for the input everyone.  

 

Yes, I tend to overanalyze things, especially when it comes to the kids. If I screw up my equipment, I'll figure out how to fix it. If I screw up theirs, they'll just say "this isn't fun". If I never got that true bar I never would have had doubts.  

 

My older boy (on the concave 120s) is a strong parallel skier (but not quite a Mikaela Shiffrin)  -- Level 7+ per his instructor last year -- needs to work on carving on steeper terrain.  Yes, I was planning to do a 1 degree base/2 degree side bevel.  The 6-year-old (on the convex 110s) is still stemming and likes to spend his time on the boxes at the terrain park on in bumps (where he survives, but is happy). I wasn't planning to play with his bevel angles until after I see how he is skiing.

 

I hope to get them out 50 days this year.  Most of it will be on soft snow, but we can get pretty icy now and then.

 

The concavity is less than a sixteenth of an inch.  The convexity bumps a bit over that near the tip.  So my take home message is this:  It's not such a big deal.  Worth seeing if the shop can make it better, but probably not worth a $40 stone grind.  

 

 

post #7 of 18

I posted in the general skiing forum about my wife's Atomic Cloud 7 skis, which are too railed from the toe peice to the shovel to fix according to the RIE tech, who seemed to know what he was talking about.  I brought them in to have them ground flat.  The comments range from that's the way they are supposed to be to it's the epoxy core that does not set quick enough while in the mold.  As it stands, they ground the ski flat under foot and improved the tail.  We'll see how it goes.

post #8 of 18

I would have the convex skis ground flat.

 

The concave skis are not a problem. As long as the base is flat about 10mm (1/2") in from each edge they will ski fine provided the edge has decent geometry and no hanging burr.  If you want to dramatically reduce the life of the ski have them ground flat.

 

Numerous skis are concave in the center of the skis and ski just find. Almost all atomic skis were like this for years. And the wider the ski the more chance they were concave in the center.

 

if the concavity were edge to ege they would skied like the were railed, but just in the center is no problem.

 

Another comment, you guys who thing all we get is soft powder snow out here on the West coast and aparticulalry around sSeattle obviously have nmot skied Alpental at night afte it has rained and then forzen and not snow for 6 weeks.

 

Trust me hwne I say we get some periods of icy boilerplate!

 

The other issue is when we do have softer snow it generally has a high water content and this can really be an issue if your bases or edges are out of whack!

 

post #9 of 18
Thread Starter 


Thanks Atomicman, I think I'll go ahead and do that.

 

Quote:
Originally Posted by Atomicman View Post

 

Another comment, you guys who thing all we get is soft powder snow out here on the West coast and aparticulalry around sSeattle obviously have nmot skied Alpental at night afte it has rained and then forzen and not snow for 6 weeks.

 

Trust me hwne I say we get some periods of icy boilerplate!

 

The other issue is when we do have softer snow it generally has a high water content and this can really be an issue if your bases or edges are out of whack!

 


Yep, that rain/freeze cycle we get sure can be fun.  Hopefully La Nina will minimize that this year (without a repeat of last January).

 

post #10 of 18

Sorry about my lousy typing!redface.gif

post #11 of 18
Quote:
Originally Posted by Atomicman View Post

Sorry about my lousy typing!redface.gif



I like crappy typing but it's the message that counts the most. icon14.gif

post #12 of 18
Thread Starter 

Just a follow up here.  I left both pairs of skis as they were to see how things went the first day.  I set the side edge angles to 92 degrees and left the base bevels alone.

 

The boy skiing the slightly concave, railed skis loved them.  He said they were fast, they grabbed the snow, they did what he wanted.  He and I were diving through trees in dodgy cover and I'd never seen him so confident.

 

The convex skis did not bring such happiness.  The poor boy was reduced to wedging at points trying to get enough of an edge angle, and he seemed less confident than he was at the end of last season.  He still had a fun day, but he said he'd rather have been on the season rentals he had last year.

 

So it's time for me to get to work fixing these things.  These are relatively cheap skis so paying for a stone grind is painful (but is better than leaving it as is).  Any thoughts on either

  1. Flattening it myself with sandpaper?
  2. Getting something like the SkiVisions base flattener?

 

I'm taking care of equipment for a family of 5, so a little investment in DIY equipment and knowledge goes a long way.

post #13 of 18


How old are the skis and where did you buy them?
 

Quote:
Originally Posted by Rolfe Schmidt View Post

Just a follow up here.  I left both pairs of skis as they were to see how things went the first day.  I set the side edge angles to 92 degrees and left the base bevels alone.

 

The boy skiing the slightly concave, railed skis loved them.  He said they were fast, they grabbed the snow, they did what he wanted.  He and I were diving through trees in dodgy cover and I'd never seen him so confident.

 

The convex skis did not bring such happiness.  The poor boy was reduced to wedging at points trying to get enough of an edge angle, and he seemed less confident than he was at the end of last season.  He still had a fun day, but he said he'd rather have been on the season rentals he had last year.

 

So it's time for me to get to work fixing these things.  These are relatively cheap skis so paying for a stone grind is painful (but is better than leaving it as is).  Any thoughts on either

  1. Flattening it myself with sandpaper?
  2. Getting something like the SkiVisions base flattener?

 

I'm taking care of equipment for a family of 5, so a little investment in DIY equipment and knowledge goes a long way.



 

post #14 of 18
Thread Starter 
Quote:
Originally Posted by Atomicman View Post


How old are the skis and where did you buy them?
 



 


They are new, so it's ironic that I bought them at Play it Again Sports.  

 

post #15 of 18


You may be able to get hem warrantied by the manufacturer.

 

Generally convexity is a manufacturing defect. The skis don't press together correctly when constructed.

 

We had a pair of Atomic Slaloms that were convex and were replace on warranty no questions asked once I sent the skis in for inspection.

 

The big issue here I think is that Play it Agin Sports imay not be an authorized dealer for the brand you bought, but you should be able to take them to an authrozed dealer and try to get them replaced.

 

The problem is going to be it is probalby not base itself that is convex, the base is being shaped by the actual structure of the ski beneath it and no amount of grinding is goin to get them flat. The base is not very damn thick. How much are they out of kilter?

Quote:
Originally Posted by Rolfe Schmidt View Post


They are new, so it's ironic that I bought them at Play it Again Sports.  

 



 

post #16 of 18
Thread Starter 


 

Quote:
Originally Posted by Atomicman View Post


You may be able to get hem warrantied by the manufacturer.

 

Generally convexity is a manufacturing defect. The skis don't press together correctly when constructed.

 

We had a pair of Atomic Slaloms that were convex and were replace on warranty no questions asked once I sent the skis in for inspection.

 

The big issue here I think is that Play it Agin Sports imay not be an authorized dealer for the brand you bought, but you should be able to take them to an authrozed dealer and try to get them replaced.

 

The problem is going to be it is probalby not base itself that is convex, the base is being shaped by the actual structure of the ski beneath it and no amount of grinding is goin to get them flat. The base is not very damn thick. How much are they out of kilter?



 



I saw this and brought them in to Play it Again Sports along with my true bar.  They said they hadn't seen ones that bad and were ready to do a warranty exchange but they were out of stock in the 110s.  To get us back on the snow -- we're planning to brave the rain Wednesday -- they ground them flat and said that if we can't get it right they'll take it up with Dynastar.  Per the fellow that tuned them, they had to take a lot of material off.

 

We'll see how things go in a couple of days, but I think it will be much better. 

 

 

post #17 of 18


That's great! Hope it works out for ya!

 

CW

Quote:
Originally Posted by Rolfe Schmidt View Post


 



I saw this and brought them in to Play it Again Sports along with my true bar.  They said they hadn't seen ones that bad and were ready to do a warranty exchange but they were out of stock in the 110s.  To get us back on the snow -- we're planning to brave the rain Wednesday -- they ground them flat and said that if we can't get it right they'll take it up with Dynastar.  Per the fellow that tuned them, they had to take a lot of material off.

 

We'll see how things go in a couple of days, but I think it will be much better. 

 

 



 

post #18 of 18
Thread Starter 

Well his journal entry today was just "I like my flattened bases!"

 

I'm glad we fixed it.

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