Here is a better image that shows the Triangles that are formed and calculated (providing I have this correct. Steve?).

Note the base of the orange triangle is measured from the horizontal position of the instep to the big toe. The height of the triangle is 95% of the belly button height(true height not pictured here). The D line is 7/10 back from the metatarsal as described earlier in this thread. Then ramp the angle of the new triangle until the top point is horizontally over the D line. That is the desired ramp angle for that size of foot and COM height(according to this theory anyway).

The math I brought earlier uses 1/3 instead of 70% for the D line. So adjust accordingly, IF it even turns out to be the correct math.

Hope the images help

I think the fundamental theory here is that the instep point noted with a circle is the natural balance point of our body to provide BOS for the COM when standing evenly centered on the foot, regardless of where the knees are or the flex in the ankles. Tilting the ramp forward a bit moves that BOS balance point to a place that may be more effective for skiing, just behind the balls of our feet.

Also note that there is something else not depicted in this image which is a triangle showing how the heel is related. Its confusing for the purpose of calculating ramp angle. But imagine a triangle connecting C to B to a new point F under the heel. That is the natural standing tripod supporting our BOS with the balance point at the instep. I say tripod because there are also three points on the bottom of the foot(heel, big toe side, little toe side).

Note the base of the orange triangle is measured from the horizontal position of the instep to the big toe. The height of the triangle is 95% of the belly button height(true height not pictured here). The D line is 7/10 back from the metatarsal as described earlier in this thread. Then ramp the angle of the new triangle until the top point is horizontally over the D line. That is the desired ramp angle for that size of foot and COM height(according to this theory anyway).

The math I brought earlier uses 1/3 instead of 70% for the D line. So adjust accordingly, IF it even turns out to be the correct math.

Hope the images help

I think the fundamental theory here is that the instep point noted with a circle is the natural balance point of our body to provide BOS for the COM when standing evenly centered on the foot, regardless of where the knees are or the flex in the ankles. Tilting the ramp forward a bit moves that BOS balance point to a place that may be more effective for skiing, just behind the balls of our feet.

Also note that there is something else not depicted in this image which is a triangle showing how the heel is related. Its confusing for the purpose of calculating ramp angle. But imagine a triangle connecting C to B to a new point F under the heel. That is the natural standing tripod supporting our BOS with the balance point at the instep. I say tripod because there are also three points on the bottom of the foot(heel, big toe side, little toe side).

*(note the ramp angle is exaggerated in this image because the height of C is not the true height of the belly button. If the triangle were its true height, it would require much less ramp angle to hover the tip of the triangle over the D line.)*