Motorcycle Instrument Clusters for Collision Reconstruction

The behaviour of the instrument cluster of passenger cars during a collision is reasonably well understood, following a number of studies over the past decade. However, one of the frequent questions asked is if motorcycle instruments can be considered in the same way as passenger cars. Motorcycle instruments work in the same way as passenger car instruments. The older models use a Bowden cable to drive a spinning magnetic cup, which drags an instrument needle against a hair spring. Newer models (typically post 2000) use a stepper motor which requires power to drive the needle to any indicated position, including returning it to zero. Hence if power to the instrument is lost as a result of a collision, there is no electrical power to the motor to move the needle, and it should be left at its last position before the power was lost. However, the accelerations experienced by a motorcycle instrument during a collision are significantly different from those of an instrument cluster housed within the dash of a passenger car. Over the past few years a number of crash tests involving motorcycles have been carried out in the USA and UK and the behaviour of the instruments were analysed to see how they perform at holding any residual reading.