True bipedalism in nature is very rare. We are the only mammals that decided to stand up out the primordial soup to walk upright around the planet, and over millions of years our feet have evolved to allow us to walk, run and jump. Then the bicycle is invented 150 years ago and the heel-to-toe movement phases the foot naturally moves through are suddenly superfluous, unhelpful even.
In walking and running, the foot goes through a dynamic phase of motion from heel-strike to
