The mechanical odometer with the star-shaped wheel was made by Lucas. (or at least mine was) You had to buy a unit specific to you tire size. They were made of metal and worked forever or until the strike pin on the spokes wore through the teeth on the wheel. Mine disappeared during an overhaul at a LBS. Anyway with the Lucas on your front fork, a second hand on your watch, and a gear chart taped to your bars, you could do anything computationally. Accurate? Probably not.
Paul Patzkowsky more snow in Longmont, Colorado