This was one of my most fun challenges. I wanted the boy on the unicycle to look realistic and unsteady, but tweaking (and revising) so many keyframes was turning out to be a chore. So instead, I rigged the unicycle wheel's rotation to it's speed and distance across the width the comp. The expression came from a Creative Cow tutorial by Carl Larsen that I can no longer find, however the technique is well described in this post from Once I had the rotation down, I rigged the boy with Duik and connected the legs, pedals and crank shafts to the unicycle wheel.