"nnn" wrote:
Well, I've read that pilot bindings should be:

a) mounted 1cm *forward* of the balance point to move the ski's balance
point between the two bars on the boot.

b) not mounted forward of the balance point, but at the balance point
because the weight of the binding moves the balance point of the combined
ski+binding backwards to a spot between the two bars.

c) and now you say pilot bindings should be mounted 1cm behind the balance
point for an unknown reason.

I'm surprised there is no consensus.

thanks, tom

I'll take a stab at this. The Pilot binding is tail heavy. A ski with
Pilot bindings mounted at the balance point will have the combined balance
point shifted about 1.5 cm behind the original balance point - a bit tail
heavy, but the secondary bar provides another (sprung) vertical lift point,
so the ski will be lifted level to the ground more or less. A ski with
Profil bindings will retain the original balance point, and will be lifted
from that balance point. Both types of bindings will ski the same in that
you will be pressuring the ski from the same position (retaining the ski's
pressure distribution). Both types will both be more or less level to the
ground in the return phase too.

Mounting bindings away from the balance point requires more consideration
because it changes the pressure distribution of the ski. Skis are designed
so that they work best with bindings mounted at the balance point, but this
ideal may not happen all the time. There are manufacturing variations and
flexes that are all over the place, it's easy to see that maybe the balance
point is not the ideal location for every ski. The NIS system with moveable
binding locations seems like a way to finally address this (for NNN). Zach
Caldwell had a little write up on this system on his website a couple of
weeks back, and I think he found that most of the Madshus that he had on the
system skied best at the balance point, but some skied best with the
bindings farther back, including on that skied best at 1.5 cm back. I
imagine that without adjustable bindings, that ski would have been called a
dud (you know, like the skis you and I buy at retail for $400-500 that are
just plain slow!).

I moved the Pilot bindings on a pair of Madshus back 1.8 cm (to the combined
ski/binding balance point) and turned a pair of bad skis into decent skis
because it improved the pressure distribution on the snow. This ski was
mounted at the balance point originally, with the combined balance point 1.5
cm behind the front pin. It now balances like a Profil binding ski, with
the main bar taking the load of the ski. The return spring doesn't have to
do as much work as it was intended to, so I bottomed out the spring a couple
of times to loosen it up and it balances/skis fine.

So going back to your choices, I would say go with the balance point because
most skis are designed for that, at least theoretically, unless the
manufacturer recommends otherwise. Mounting 1 cm in front of the balance
point would make the ski tail heavy (yes, balance is still between the
bars), but maybe not enough to matter. Going just from my minimal
experience, I would rather mount a binding farther back than forward (seems
to make the ski faster). Note that mounting the bindings 1 cm back would
also result in a combined balance point still between the two bars (maybe
0.7 cm behind the main bar) because of the tail heaviness of the binding.
Maybe this is considered better balanced than mounting at the balance point
(where the combined balance is 1.5 cm behind the main bar) - it makes the
main bar take up more weight, a bit more like the Profil binding in terms of
balance. Atomic's recommendations seem to take this line of reasoning,
though they vary the location by ski length (mount 1 cm behind for 190 cm
skis, 0.5 cm behind for 184 cm skis, and at balance point for 178 cm). I
think Fischer recommends the balance point.