"In any case, Price and Donne measured minimal and maximal ankle angle as a function of seat tube angle (over the range of 68 to 80 deg) and found very little difference. "
That was my question. Would the steeper TT/Tri position effect the foot position relative to the ground, as opposed the the body? So, by ankle angle you mean foot/shoe to tibia? And that is what stays the same?
To determine the angle of the ankle with respect to horizontal, Price and Donne placed reflective markers on the lateral malleolus and the lateral aspect of the fifth metatarsal-phalangeal joint. With the saddle set at 100% of trochanteric height, changing the seat tube angle from 74 deg to 80 deg only increased the ankle angle by 4.5 deg.