Bicycle computers are useful addition to your bicycle. In their basic form, bike computers provide the ability to see how fast, how far and for how long you have been riding. They can be used on mountain bikes, road bikes and almost all types of bike with settings for the different wheel sizes. Wired are the cheaper version, with wireless becoming more prevalent as the technology increases. More advanced versions of bike computers come with cadence, altitute measurements and can even be coupled with a heart rate moniter or gps device.