Tuning Volkl BMT 109

[mtb]

I just got a pair of BMT 109s, my first reverse camber skis. I understand the idea of "detune past the contact points" on skis with tip and tail rocker, but what's the recommendation on reverse camber skis like these?

[sruffian]

I ski bmt 94's - also full rocker.

The advice is the same - de-tune from the contact points to the tips. The bmt's have slightly less tip taper than the average ski these days, so there isn't that much distance from the widest point to the tips. When you lay a full-reverse ski on edge, it still flexes. You can think of the reverse camber as being 'pre flexed'

FWIW I keep my bmt's pretty sharp as they're my spring skiing / bc steeps ski, and I've never had an issue with them feeling hooky on the factory tune.

[mtb]

Thanks @sruffian, appreciate the advice.

[mattig]

Where is the contact point on a full rocker ski?

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[Jongle]

Where is the contact point on a full rocker ski?

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Lay the ski on a flat surface (e.g. the floor) and tilt it onto its edge. Its contact points are the points closest to its tips and tails where it's still touching the floor.

[1000-oaks]

Picked up a pair of 2019's in the 177 length and just mounted and waxed them. Found the bases are a bit concave under the binding area, can't wax the middle 2/3 of the base unless you only iron half of the ski at a time. They're fine toward the tips and tails, where the iron makes contact with the base all the way across. Volkl markets these as full rocker, but my pair is actually flat (maybe even 0.5mm of camber) from about 6" in front of the toe piece to just behind the heel piece.

Given that the flat section is so short, wonder if being railed is even much of a problem, other than being annoying to wax. If I took them to a shop that's a Volkl dealer, would they charge for a pass on the stone grinder, since they're brand new? Or could just wait a season and do it after the edges hit some rocks, and get more benefit from the grind.

[swissiphic]

Picked up a pair of 2019's in the 177 length and just mounted and waxed them. Found the bases are a bit concave under the binding area, can't wax the middle 2/3 of the base unless you only iron half of the ski at a time. They're fine toward the tips and tails, where the iron makes contact with the base all the way across. Volkl markets these as full rocker, but my pair is actually flat (maybe even 0.5mm of camber) from about 6" in front of the toe piece to just behind the heel piece.

Given that the flat section is so short, wonder if being railed is even much of a problem, other than being annoying to wax. If I took them to a shop that's a Volkl dealer, would they charge for a pass on the stone grinder, since they're brand new? Or could just wait a season and do it after the edges hit some rocks, and get more benefit from the grind.

This thread might provide some reference for dealing with that issue. Obviously it's a different ski and your results could be more auspicious using similar methods of attempts at healing.

https://www.tetongravity.com/forums/...g-gone-to-shit

If grinding doesn't get em flat, one measure might be hand filing or base planing so that approximately 1.5cms of base is flat inboard from each side edge. Atomic cap/foam skis in the REX era apparently had frequent issues of base concavity. A pro ski tech that worked on their race skis I talked to decades back suggested employing that process to tune skis with concave bases. Apparently this results in a ski that performs like one that has a completely flat base.

[sruffian]

I'd be pissed because of how thin they are. I have older 2016 bmt's, and I am certain I will get far fewer than normal base grinds out of them than I would a normal ski. Correct me if I'm wrong here, but there's just no way they used as much base material in these as you find in a moment or on3p.

Based on that and the fact you say they're 2019's, and showing camber, I'd see if volkl will replace them. Like if you place the bases together you can see light between them underfoot? Weird.

If you're gonna hold on to them, there's nothing to lose by trying to ski them and seeing how railed they are before base grinding them. My bet is that they'll still be twitchy if they're railed underfoot, it's not dependent on being railed on a cambered section

[1000-oaks]

Like if you place the bases together you can see light between them underfoot? Weird.

Yep, you can lay one ski on top of the other (base to base), and insert a piece of paper between and slide it forward and back to the contact points. I'm good with that though, and prefer it to being true full-rocker. The concave base thing is a little annoying though, have never had a ski with this issue.

[ACH]

^^^
Something is definitely off with those if that is the case. That ski is damn near perfect per what they should be. I've got well over 200 hundred days on mine and finally had a delam after years of abuse. Next to the Explosiv, they may be one my favorite skis ever, I will be getting another pair in the Fall.