Last couple of rides I've been out on my knees have begun to hurt after about 15 miles. Usually takes a couple of days to recover. I'm currently using Shimano SPDs on all my bikes, have done for about 18 months now but the problem has only just started in the last few months.
Do I need to get new pedals, or is it just a case of tinkering with cleat position? I'm going to try the latter, but don't have any real idea of whats a 'good' cleat position. Any suggestions would be much appreciated as I'm currently trying to ramp up the training and this is threatening to derail that somewhat.