Well, I hope nobody minds me starting a new thread on this one. I've done a search but can't seem to find an answer.
Can anyone throw any light on my knee problem? I get this feeling as though something is gradually tightening up round the knee; after a few revolutions it then "clicks" and feels normal again. This then repeats itself. It's not painful, just uncomfortable, only happens when I am on my bike and sometimes stops after about 20km. I warm up into my rides using a low gear and my pedals have plenty of float (look with the red cleats).
Am I missing some obvious thing that could cause this?

Basically, although it doesn't hurt, I don't want to wait until I have wrecked my knee.

Thanks, Bron