I would like to discuss the fore/aft binding placement issue and seek your feedback and opinions. I suggest that you read an excellent series of articles on this subject published by Peter Keelty on the RealSkiers WEB site.
In brief, the maximum ski bending sensitivity would exist when your body weight is applied to the ?bending? center of the ski. As the article mentions, different manufacturers place the bindings in different spots in respect to fore/aft alignment even for the similarly shaped skis. The binding placement is also similar to the boot alignment process since every person is different in respect to their fore/aft ?neutral point? location. Of course you may correct fore/aft position by moving your legs or body but the best initial condition exist when you are centered on the ski in the first place. Otherwise you would have to apply muscle efforts to continuously offset your ?neutral? position to the match the ski ?neutral? position.
Peter mentions few methods allowing for correct fore/aft binding placement. I don?t want to re-type all this information here (you can look it up yourself). He mentions the traditional ?ball of the foot? method and alternatively using the Campbell Balancer device. Honestly, I don?t understand the physics behind the ?ball of the foot? method. I feel that it might be OK for the straight skis, but modern shaped skis have different width for the tip and tail so the middle of the ski is not necessarily the actual ?bending center? point. Since the stiffness and the bending characteristics of the skis do vary a lot I am willing to trust the manufacturers ?middle mark? point on the ski.
The individual skier fore/aft ?neutral? point is of more interest. I studied the info on the Campbell Balancer including the patent which covers it. In essence, it?s a tipping board. So I decided to use the tipping board which I made for balancing exercises to measure where my fore/aft balance point is. Instead of lateral balancing on the board while standing on one foot (normal usage) I stand on it with both feet and balance in the fore/aft direction. I use a small mirror which I place on the floor next to the board to see where my boots are in respect to the center mark line on the tipping board after I assume the "skiing" body position and try to find a balance point.
I think that ideally the boot ?center mark? should match the center mark on the tipping board when you are assuming correct posture and reach the balance. I found that my balance point is reached with the middle mark on the boot approximately 20 mm ahead of the center mark on the board. I was constantly in the back seat. Since I am using Atomic bindings which are really easy to move fore/aft, I moved them 20mm forward. If you decide to repeat my experiment, I also suggest that you try to move the binding fore/aft a little bit (like 5 mm) around the new ?measured? point in order to find the exact binding position. The tipping board measurement method is not as precise as the Campbell Balancer but I believe that it will give you a pretty good idea in our particular situation.
I am very happy with the results and feel a big difference this adjustment made in my skiing. I think that fore/aft binding placement is especially important for PMTS ? based skiing since we rely mostly on tipping and edging, which in the end results in bending the ski.