Originally Posted by allan o'neil
I am a shade over 5'10" and weight 205lb. generally quite fit...very strong calf muscles. My boots are 310mm sole length. I have numerous skis...all with different bindings...however I think I would give my Fischer AMC 79's with Railflex bindings a try first as I use them most often. I find they ski best when I force my weight to stay over my arches.
There are four parameters that I look at in the fore/aft plane:
1) boot board ramp angle - affects location of cm. and is one aspect of "net forward lean" equation. This angle can be changed to better match your ankle range of dorsiflexion. (less dorsiflexion needs a more open ankle joint or less "net forward lean", while a hypermobil r.o.m. needs less ramp and more forward lean to create a greater "net" forward lean.
2) forward lean of shaft - affects amount of ankle and knee flexion (more fwd lean equals more flexed joints, less equals less. This angle also affects where the knee plumbs over the ski. Contrary to popular belief, changing forward lean does not move your com forward or back. Forward lean is the other half of the formula which determines "net" forward lean (fwd lean less ramp angle = net forward lean).
3) Delta angle - is created by the stand height differential of the heel and toe pieces of the bindings. Different binding manufacturers and models create different angles which need to be considered in the whole fore/aft scenerio. Your boot sole length also has an affect on this angle because the smaller the boot sole the steeper the angle, and the longer the boot sole the shallower the angle, created by the same binding. The delta angle affects where the knee plumbs as well as the amount of flexion and the location of the com. It does not change the net forward lean at all.
4) Binding placement is the fourth consideration which noticeable affects where the sweet spot of the ski is located under the boot which in turn determines where you need to stand on the ski to affect the best turning. This is not easily experimented with unless you have demo bindings which allow independant heel and toe placement along the ski. In general the most universally accepted positioning tends to be placement of the ball of your foot on the center of the running surface as a good starting position.
SOOOoo. when considering all these parameters and systematically adjusting them, one can find their optimum position over the skis. In your situation, "muscular calves" (may create more forward lean), 310mm boot sole (medium), and Tyrolia Railflex bindings (medium stand height differential) it is difficult to say there is anything grossly out of the norm but I would suggest experimenting with a piece of 3mm thick bontex insole shim placed between your toe AFD and boot toe. This will pull your whole boot more upright creating a slightly taller stance and more shin to tongue pressure on the boot. Try skiing this way for a few runs then try the shim between your boot heel and binding. you should notice a marked difference and perhaps prefer one way vs. the other. If you prefer the way this lift feels a boot lifter can be permanently affixed to your boot sole and the toe or heel lug routed accordingly to return the boot to DIN specs.
hope this helps your understanding of what is possible.