Cycle computers are a great training aid not just for professionals but for anyone who rides a bike regularly. Tracking your current speed, distance, time elapsed, average speed and total cumulative distance as well as a multitude of variables such as height gain, temperature, cadence and heart rate depending on model and functions is simple with details available at the touch of a button. Having all this information to hand is not only useful when riding but also for logging any training done and keeping an eye on your fitness levels over time.
Compatible for use on both road and mountain bikes, cycle computers are very small and unobtrusive, are easy to install and calibrate and once correctly set up there is no need to adjust again. They work by using a small magnet attached to the spoke which passes a transmitter on the frame or fork which delivers a signal to the display unit on the handlebars either wirelessly or with a tiny wire. If you want to use one on your indoor trainer please make sure you get a rear mounted model as the reading will be taken from the back wheel, if using rollers you can use either model.