I got a wireless bike computer from decathalon in UK, and it works fine. The only problem is that the instructions don;t specify how highut the magnet on the wheel, or the sensor on the fork. THere's a crude diagram that shows it roughly 2/3 up the fork (maybe, it's hardto tell), but I was talking to a guy who said he understood that sensors in genera should go at the centre of the fork.
Anyone know? I'm guessing it's critical, as if it's too high it'll go too fast, and too low it'll go too slow.