I made the original Satyr Legs feet with bicycle tires bolted over the steel feet. The problem with using real tires is they have a lot of grooves and very little gripping surface; this reduces friction on the road. I needed a lot more contact with the ground.

To solve this, I used perforated steel and poured rubber to cast directly onto the steel feet. This is a tough rubber called VytaFlex 60. It is critical you first abrade the steel surface to remove surface oils before casting.

A closeup of the foot after the jump.

After my initial test with the legs, I decided to make quite a few changes. The legs need to be longer. (You can see in the picture where the old foot was cut off and the new, longer version welded in.) The joints are a bit wide and need to be trimmed, and there should be more movement in the foot. The satyr feet are spring-loaded, but not enough to hide the actual foot during movement. I’ll need longer springs and bolts.