Bicycle computers and speedometers
A speedometer measures the current speed and displays it graphically. The term comes from the ancient Greek and is composed of "tachýs" (fast) and "métron" (measure, scale). In most cases, the speed is displayed analogously with a speedometer needle or a digital display. Many speedometers nowadays also include many other functions such as odometer, time, altimeter or calorie counter. For cyclists who travel a lot on unknown terrain, a navigation device in tachometer format is also available.