Originally Posted by operator
Sounds like it's a battery issue or the magnet is going too fast for the detector to record speed. Try placing the magnet/detector closer to the hub.
Thanks, but I don't think it can be the sensor, as I can always fix the problem by wiggling the computer. Also, it's only just started playing up and the sensor's been in the same place for ages. The instructions say the battery should last 3 years at an hour a day. That's about 8 times as much use as I've had out of it. But I'll replace it and see what happens.
BTW, it's not cordless - in fact it's got a thick wire which is meant to stand up to mtb-style abuse.