Armature deforms when using follow path

I simply can’t get around this.

I create a leg rig from a tutorial.
I take the controlling bone and set it follow a path.
The entire Armature flips out and goes everywhere.

Is there a way to get a Leg rig to follow a path in a circle?

Can anybody explain this bizarre behavior?


Pedal StrokeV01-03.blend (494 KB)