Very easy to set up - simply attach the small, secure magnet to a wheel spoke, the sensor to a fork and the holder for the control/display unit to the handlebars. Clear instructions allow you to select preferences and input the circumference or your wheels (by either measurement and easy calculation or by selecting from a list of tyre sizes in the booklet). Works for any size of wheel or type of bike. Automatically detects motion and calculates speeds and distances. Only improvement I would like to see is easy toggling between kilometres and miles (this choice seems only to be made during initial setup - it can be changed but this entails "starting again"). In use the main unit clips on and off without difficulty and the whole thing seems unphased by a rough ride. I also have the next model up which is just as good, does toggle between imperial and metric and has a back-light. Oddly, I think I prefer this one! Many people will find that this does all they require of a cycle computer - think carefully before spending (a lot) more on e.g. a GPS based system.