bicycle speedometer

The novel feature of this bicycle speedometer is that it switches itself on when the bicycle starts to move and switches off when the bicycle stops, thus prolonging battery life without the need for a manual on/off switch. Speed sensing is carried out by a reed switch attached to the bicycle frame, which is actuated by a magnet or magnets fixed to the wheel spokes. Electronics purists who scoff at `unreliable` electromechanical switches need have no fears for the long-term serviceability of this arrangement. The life of~ reed switch is typically I 08 operations. Even with a small ( I O inch) wheel biclcle this gives a life of