An Unusual Design
The Megola had a unique design: it boasted a Monosoupape rotary engine mounted within the front wheel. The engine contained five cylinders with side-mounted valves and it displaced 640 cc (39 cu in), a total size equivalent to many modern bikes. The crankshaft was the front axle, which remained stationary while the cylinders rotated with the wheel. A hand-controlled butterfly valve was located in the hollow crankshaft to regulate throttle. Power output was a meagre 14 bhp (10 kW) but was applied directly to the wheel. This arrangement produced a very low centre of gravity and provided for excellent handling.
"The 5 cylinder star-engine was mounted in the front wheel, and the wheel turned around six times slower than the crankshaft did." 
The engine was very flexible, lacking both a clutch and a transmission. Starting it required a person to either spin the front wheel while the bike was on its stand, or to push-start. The cylinders could be disassembled without having to remove the wheel spokes in order to service the engine. The tires were tubed with the front inner-tube being a circular sausage shape rather than a complete doughnut-like torus shape, so that it could be changed without removing the wheel and engine. The box section frame contained the main fuel tank which fed by gravity a smaller tank mounted on the axle. The front suspension consisted of semi-elliptical springs.
The top speed was 85 km/h (52 mph) resulting in a win at the German Championship in 1924, while later, sportier models were said to be capable of 140 km/h (88 mph). A total of 2000 Megolas were built and only 10 rideable examples remain, with one existing in the Guggenheim Museum in New York, USA.
Killinger and Freund