Cycle computers, or speedometers, are tools designed for the serious bicyclist. Speedometers allow a cyclist to gauge speed, travelling distance and even cadence or pedalling speed. With the wide variety of cycle computers available to today's cyclist, the installation process can be easily misconstrued as a difficult undertaking. Luckily, the task is much easier than it appears and often requires only a screwdriver and a pair of scissors. Robustly-featured systems, however, may require more detailed steps so familiarise yourself with the process by referring to the owner's manual before beginning.
Lay out the contents of the speedometer kit and take an inventory of its parts. Your kit should include a spoke-mounted magnet, speed sensor, a set of zip-ties, the speedometer and a mounting bracket.
Set up the speedometer to fit your bicycle. Most cycle computers have a "Reset" button on the back of the unit. Depress the "Reset" button with a short pin. Select the measurement units, using either miles or kilometres, and the circumference of the front tire. Refer to your speedometer's owner's manual for tire circumference conversion charts and information.
Select a position along the handlebar to mount the speedometer bracket. Place the rubber mounting pad, if supplied, onto the handlebar to protect the painted finish and mount the bracket over the pad. Secure the bracket to the handlebar with zip-ties, tightening the zip-ties sufficiently to prevent the bracket from moving. Slide the speedometer onto the bracket and press it downwards until the speedometer locks into place.
Mount the magnet onto one of the front tyre's spokes, securing it in place by tightening the clamp on the backside of the magnet with a screwdriver.
Mount the speed sensor to the front fork, securing the sensor with zip-ties. Select a location that is directly over the path of the magnet as it turns with the front wheel. The distance between the sensor and magnet should not be greater than 3mm to provide accurate speed readings.
Route and loosely secure the speed sensor's cable along the front fork and to the handlebars using zip-ties. Connect the cable to the speedometer and turn the handlebars completely to the left and right to ensure that you have enough cable slack. Tighten the zip-ties completely and trim away any excess with a pair of scissors.
Test the speedometer by spinning the front wheel by hand. Ensure that the sensor and magnet do not come into contact with each other and that the speed is displayed on the speedometer.