Abstract
A mathematical model of a rigid-framed motorcycle running freely is extended to include the effects of torsional flexibility between the rear wheel and the frame. It is found that the effect of fork flexibility on capsizing is negligible and on wobble slight, particularly in comparison with the effect of steering damping. Furthermore, it is concluded that torsional flexibility in the rear fork of the motorcycle will reduce the damping of weaving at medium and high speeds, while affecting the capsize and wobble modes very little.