Most bike riders will have some sort of “bike computer” which tracks how far and fast they have been riding. Very few bike riders, however, would have a good idea of how their bike computer works! If you fall into this category, or just like the idea of making your own bike computer, this project is for you. The Arduino powered bike computer uses a reed switch mounted on the frame of the bike which is triggered every time a magnet on the spoke of your bike passes it, the Arduino counts how many rotations have occurred and calculates the distance you have travelled and displays it on an LCD. This is a really great project, it is easy enough to complete in a few hours, but challenging and useful enough to keep you interested! If you want to find out more about this project, check out the instructions written by electroguyz.