Abstract
This investigation has been made to see how far a mathematical analysis will enable design to be either modified or kept on the right lines in machines in which stability and ease of steering are of the first importance. It is apparent that a cycle may be ridden "hands off" along a good road, that is, without human will being applied to the steering. Under this condition any small wobble that may occur may disappear again, the machine naturally returning to a straight ahead motion, or the wobble may increase and cause trouble. The first condition is here called stability, and the second instability.