I did a search and had no luck. So why do bikes have different sized wheels, in particular why is the the rear wheel smaller? Is there a technical reason or is it legacy left over from old bikes with 2 rear shocks? I come from a mountain biking background and mountain bikes with smaller rear wheels have been tried but are not prevalent because they have disadvantages. The main one is that they turn/corner like crap because of the different wheel radii when leaning in a corner. Wouldn't dirt bikes corner better if they had the same diameter in front and back?