The web site at Bicycle Computer.org has been set up to give you lots of information and advice on the large range of bicycle computers on the market today. With such a large variety of different prices and types of computer available you might find it hard to decide what you need, so we are here to help.
What is a Bicycle Computer?
A bicycle computer (also called a cyclocomputer or cyclometer) is a device mounted on a bicycle that calculates and displays cycle trip information, similar to the instruments in the dashboard of a car. The cycle computer with display, or head unit is usually attached to the handlebars for easy viewing by the cyclist.
History of Bicycle Computers
Curtis Hussey Veeder invented the Cyclometer all the way back in 1895 . The Cyclometer was a simple mechanical device that counted the number of rotations of a bicycle wheel. A cable then transmitted the number of rotations of the wheel to an analog odometer visible to the rider, which converted the wheel rotations into the number of miles traveled according to a predetermined formula. After founding the Veeder Manufacturing Company, Veeder promoted the Cyclometer with the slogan, It’s Nice to Know How Far You Go. The Cyclometer’s success led to many other competing types of mechanical computing devices. Eventually, cyclometers were developed that could measure speed as well as distance traveled.
Modern Bicycle Computers
A modern basic cyclocomputer might display information such as current speed, maximum speed, trip distance, trip time, total distance traveled, and the current time. More advanced models also might also display altitude, incline (inclinometer), heart rate, power output (measured in watt) and temperature as well as offer additional functions such as average speed, pedaling cadence, a stopwatch and even GPS navigation. They have become useful accessories in both recreational cycling as well as road racing and mountain biking.
The head unit usually has a liquid crystal display, and it may show one or more values at once. Many current models display one value, such as current speed, with large numbers, and other factors which the user may select, such as time, distance, average speed, etc, with smaller numbers.
The head unit usually has one or more buttons that the user can push to switch the displayed values, reset items such as time and trip distance, calibrate the unit, and on some units, turn on a back light for riding at night.
Bicycle Computer Wheel Sensor
Traditional sensors use a magnet attached to a spoke of either the front or rear wheel. A sensor based either on the Hall effect, or on a magnetic reed switch, is attached to the fork or the rear of the frame. The sensor detects when the magnet passes once per rotation of the wheel. In alternative systems, a sensor may be attached to the wheel hub instead. Distance is determined by counting the number of rotations, which translates into the number of wheel circumferences passed. Speed is calculated from distance against lapsed time period.
More modern sensors use a magnetic field, created by a magnet attached to a spoke, to determine an angle of wheel rotation for a fixed time of several milliseconds. The sensor is mounted on a quick release and works like a compass pointing to a magnet like a north pole arrow. Magnetic field sensors provide higher accuracy of speed and acceleration measurement.
A further alternative is GPS based systems which do away with the wheel sensors altogether. The Garmin range of bike computers are examples of this type of computer.
Bicycle Computer Cadence Sensor
To measure cadence, a magnet is mounted to the crankarm, with an accompanying sensor mounted to the frame.
Bicycle Computer Heart Rate Monitor
A heart rate monitor can be integrated into the bicycle computer, using a chest strap sensor which is worn by the rider under their clothes.