What do steering dampers do?

Under some operating conditions, motorcycles suffer from oscillation problems. This has been established through usage and through measurement programmes. Corresponding theory is well established. The main lateral oscillations are weave and wobble. In straight running, the weave mode is well damped at moderate
speeds, but becomes less so as the speed increases. Motorcycle natural frequency rises from zero at very low speed to somewhere in the range 2−4Hz, depending on the mass and size of the bike, the lowest frequencies corresponding
to the heaviest motorcycles. The only properly documented wobble oscillations involve moderate speeds, although there are many anecdotal accounts of wobble at high speeds. Theoretical results indicate that the torsional stiffness of the
motorcycle frame at the steering head determines whether a machine will be prone to wobbling at medium speeds (compliant frame), or at high speeds (stiff frame). The frequency of the mode does not vary much with speed, being governed primarily by the mechanical trail, the front tyre cornering stiffness and the front frame steer inertia.It is normally in the range 6 − 9Hz. Stiff framed machines, being prone to wobbling at high speed, often depend on
a steering damper for satisfactory wobble mode damping.
Normally, however, a steering damper will destabilize 

the

high speed weave. In cornering, the above lateral modes