I've got that £12 one, had it for around 7 years and its been very good IMO. When the batteries start to go dead it tend to get interference from LED's etc (it stops recording every cycle, so you get a reading of 0-4mph when you freewheeling down hill) That isn't really a problem though as its just a hint to replace the battery. Its been a very rugged computer IME and has experienced all weathers and still come good :-)