"Keep the heel down." Good
advice? Within a small range, it is possible to change the length of the
"Shin" (See Figure 1) by pedaling with the heel up or down.
The following plot shows Power for changes to a rider's "Shin Length".
This plot shows that the power is less for longer shin
lengths. "Keep the heel down" would seem to be good advice.
However, results based on your data may be very different.
Note: The Power vs. Shin Length Plot assumes that the distance
from the point of rotation of the hips, point d in Figure 1,
is at its maximum distance from the center of the bottom bracket. Thus the
position of point d must change in order to maintain a feasible geometry
(to keep the feet touching the pedals)