Bicycles are generally more of a logistical factor in a campaign rather than something one would ride in battle or under fire. In military terms, bicycles are most useful in extremely rough terrain (like Malaya, New Guinea or Vietnam) where motorized transport isn't practical. One example that springs to mind is Vietnam and Dien Bien Phu in particular, where a sophisticated system of bicycle logistics was developed in order to surprise the French (and later American) forces by the unexpected staying power of Vietnamese forces in remote locations. http://www.historynet.com/pedal-power-bicycles-in-wartime-vietnam.htm