Way back when, there weren't any mountain bikes! There were only "ten speeds" and "cruisers". Most of the nitro cars were pan chassis without suspensions (and we used model airplane engines!). Some had springs on the front wheels (no shock absorbers); a very basic suspension. The cutout, in the chassis (pan), for the flywheel was made large enough to allow starting with an upturned bicycle wheel. Many times the cutout went right through the edge of the pan. There was plenty of room for the bicycle tire.