I would have responded to you eariler but I got myself trapped in this boxcar program.
I started from defaults and went 925 in 10 generations with a two-wheeled thing where the rear wheel was smaller (by half) then the front (until it flipped over of course).
Restarted and went 905 in 15 generations with a pretty good looking roadster with two-even wheels on a short wheel base.
Restarted again and when 966 in 15 generations with the most god-awfull ugly thing that looked like a bike with a small third wheel half-way between 2 larger wheels and it had one spike out the back end and a larger spike over the front wheel. Seems to have kept it balanced as this one never flipped.
Anyway, I've wasted a number of hours on this sillyness now so "THANK YOU VERY MUCH, JACK!"
Nice find.