Cateye Strada Wireless
There are almost as many bike computers as there are bikes. Some measure your heart rate and map your route using GPS, but if you just want to know how fast you're going and howfar, Cateye makes the simplest and most reliable models on the market. The Strada, which does away with tanglesome wires, is a cinch to fit, doesn't cut out in the rain, and has just one button (it's hidden behind the computer - the whole unit works as a switch to flick between modes).
Where: Wiggle (www.wiggle.co.uk)
How much: £40