BINDING PLACEMENT I Need Help!

[mtbakersnow]

My 23 year old son's new Dynastar Big Troubles were earlier taken into the local shop by me, and I asked them to be mounted 2 cm behind ... and this is where it gets dicey, either the center line or where they "normally" get mounted, I guess I forgot EXACTLY what I asked? They mounted them 2 cm behind center, and it is ridiculously forward, looks like there is no shovel at all, the son, being a pretty damn good skier, tried them for the first time yesterday, can barely ski with them - the binders are so far forward, and is MIFFED. We go back to the shop today.
FIRST, where should they be mounted?
Second, and even if I asked for 2 cm behind center - not sure that is exactly what I said, if that is so unusual - should, maybe the shop have asked if I was certain about the mount.
ALL SUCKS! I would appreciate your advice. Thanks!

[Speedfreak]

Ooooh, that sucks. Those sticks have a mount line that is pretty far forward anyway - couldn't imagine trying to ski them mounted 2 back from true center. When I had mine I mounted them 2cm back from the line, and ended up moving them to -3 because I kept burying the tips. Get em remounted -2cm from the line, then go ski.

[DropCliffsNotBombs]

Careful what you ask for with modified binding mounting! The manufacturer built the ski to be mounted in one specific spot on that ski. Others have a small "range" to mount within. 99% of skiers DO NOT need to screw with their mounting positions! There's nothing steezy about purposefully having your bindings mismounted.
In your case, just have them remounted correctly... and pay for it again. The shop didn't screw up in your case.

[Cirquerider]

mtbakerskier, the best way to get your son balanced on skis where you don't trust the factor mount markings is to determine the correct location for the ball of the foot (BOF). The first step is to determine where the true ski center is, obviously, on twin tips, this is farther forward than for squaretails. Just put the skis together base to base and mark where the skis contact each other at the front and rear, then use 1/2 that distance to find and mark the true ski center. For most freeskiers, having the ball of the foot directly over the ski center is ideal, while park skiers would generally benefit from having the boot center over that ski center.

Once the ski center is marked, you need to know how to line up the boot. There are a couple ways to find the BOF location in the boot. Pull out the boot liner and have your son put his foot in the liner (with the footbed/insole in it). Make sure the heel is all the way back. Now have him flex forward bending so that he weights the ball of his foot. Mark on the liner (with tape or a marker) where the center of the ball of the foot is. You can ususally feel the ball of foot because it is the location that protrudes, carries the most weight and flexes. You can even stand over a dowel or pencil and feel the ball of foot location through the liner. Mark the location on the liner.

If the shell is semi-transparent, you should be able to see the marked BOF location in order to mark the outside of the boot and sole. So, if this is the case, simply reinsert the liner being careful to fully seat it in the heel, and mark the boot.

If the boot is opaque, you may be able to transfer the mark onto the boot board (zeppa). Use a piece of tape or make a scratch in the zeppa you can feel, then insert the board into the boot and use finger pressure or tapping to locate the ball of foot location and mark it on the outside of the boot. There are lots of other ways to find this location, and a thread on Epic once suggested small magnets. Do your best to get it as accurate as possible.

Now that you have the BoF mark on the outside of the shell it can just be lined up with the BoF mark on the ski (running/contact length divided in half). Using a right-angle straight edge you can place a new midsole mark on the ski by carrying it down from the boot's midsole mark. Now mount the bindings according to the new midsole mark on the ski. Tell your shop to line up the marks.

[DropCliffsNotBombs]

Wow, all that and still no mention of the skis waist?! That is one important point to consider when figuring out where to put the boot on the ski. Wouldn't it be great if you could just stick the boot on there based purely on the overall length?
I do like your theory of BOF mounting though. You just need to consider more measurements into the equation than just the skis length I think. Cheers!

[Cirquerider]

I disagree. I have used the BoF method for lots of skis, and seems to result in ideal positioning. Somewhere around here I put into the official AK Rocket Swallowtail thread that I used this method, and it lined up perfectly with the revised marks on the 2006 ski. I used it on 05-06 Mantras, and it turns out BoF was 2-cm back of the factory mark; a location preferred by nearly all freeskiing maggots. I don't have reference to reverse sidecut or rockered skis, but I'd be surprised if it didn't line up.