A simple engine system propels a bicycle by applying power directly to the wheel through a roller. This roller, typically driven by a small gasoline or electric motor, makes contact with the tire’s tread, transferring rotational energy and driving the bike forward. A common example is a small, gasoline-powered unit mounted above the rear wheel, with the roller engaging the tire’s top surface.
This method of propulsion offers a relatively straightforward and inexpensive way to motorize a bicycle. Historically, such systems provided accessible motorized transport when other options were limited. The adaptability to various bicycle frames and the generally simpler mechanics compared to integrated drive systems remain advantageous. These systems can provide an efficient means of short-distance travel or assistance on hills, broadening accessibility for riders.