Bicycle computers, or cyclocomputers, are popular electronic devices that
can monitor distance travelled and travel time, as well as instantaneous
and average speeds. Some units are equipped with GPS locators, heart
rate monitors, and altimeters as well. The display unit of a bicycle
computer is mounted on the handlebars. Sensors attached to the frame, fork, wheel hub, and/or
crankarm, measure wheel rotations and crank arm rotations. Some
bicycle computers use wired connections between the display unit and the
sensors, while others use wireless connections.
A bicycle computer measures the distance traveled, by means of a magnet
located on a wheel spoke. Every time the magnet passes a sensor in
the wheel fork, it increments a counter, and multiplies its value by the
circumference of the wheel. Bicycle computers are calibrated to
individual bicycles and must be set up accordingly, but they provide
valuable information for both the avid and casual cyclist.