Abstract: A motor cycle which is suitable both for use as a trail machine and as road bike has an engine and gear box assembly which forms an integral part of the monocoque frame of the motor cycle. The gear box has an input shaft, an intermediate shaft and an output shaft and a chain driving sprocket mounted on the output shaft. The rear wheel of the motor cycle is mounted in a swing arm, the pivot axis of which is coincident with the axis of the gear box output shaft and the rear wheel is driven by a chain passing over the sprocket on the output shaft and a sprocket attached to the rear. Since the swing arm axis and output shaft axis are coincident, the swing arm and rear wheel are able to accommodate large suspension movements without affecting the chain tension because of these movements.