They are no longer just odometers and speedometers: today's bicycle computers are also navigation devices, tour planners and fitness trackers all in one.
The classic bicycle computer measures speed, driving time and distance travelled. A magnetic sensor mounted on the bicycle wheel transmits the recorded data to the bicycle computer on the handlebar by cable or radio. Classic speedometers such as those offered by Sigma Sport, Ciclosport or VDO have simple LCD displays, are powered by batteries and operated via pushbuttons.
More modern are the bicycle computers with GPS. You do not need any additional mounting effort because the receiver is directly integrated in the device. A distinction must be made between GPS computers with and without routing function. By means of a barometric altimeter the altitude can be defined more precisely in the mountains.
The GPS computers without routing function from Wahoo Fitness, Bryton or Polar are somewhat cheaper, relatively small and can record additional training data. They are often equipped with Bluetooth and the radio standard ANT+ to be connected to cadence sensors or heart rate bands or pulse belts.
Navigation devices with routing functions from Garmin, Teasi or Lezyne are available with or without map display. Velonavigation devices, which work without map material, indicate the direction like a compass. You can load route data onto these cycle computers in advance in order to follow them.
GPS velocomputers with map display are full-fledged navigation devices that are comparable to car navigation devices. In most cases, a Europe-wide base map is pre-installed. For mountain bikers, devices with topographical maps are recommended in order to find the way safely in the terrain. Velo-Navis are often equipped with a colour display and a touch screen function. Depending on the range of functions, various fitness data can be recorded, smart notifications sent or routes planned. Among other things, you can create individual training plans with goals, analyze VO2-Max values or calculate calorie consumption. By integrating various apps such as Strava, Trailforks, TrainingPeaks or Komoot, the results can be shared via smartphone.