Originally Posted by Al1943
Two suggestions, if you haven't already tried these.
1) Raise your saddle until your leg is nearly straight when the pedal is at 6 O'clock.
2) Speedplay pedals.
Al
Can't speak to the Speedplays, although some of my friends love them. But the seat height is critical, regardless of pedal. The general rule of thumb is that if your knee hurts in the front, like you describe, raise the seat - if it hurts in the back, lower the seat. So raise that seat as suggested in the quoted post. If that doesn't work (and Speedplays or other floating pedal systems don't get it done), see the doctor - preferably a sports doc who won't just tell you to stop riding.
A cheap way to see if having pedal float will make a difference - get some rat trap pedals and toe clips and see if your knee problem abates. If so, a pedal system that allows some float will likely make a big difference. The dirty little secret of clipless pedals is that they introduced a whole new set of knee problems for some folks that never used to exist because the old clips-and-straps set-ups always allowed for some float naturally, even when using cleats and cinching the straps down. (Your foot would also go to sleep, demanding some relief from tight straps, long before your knees would complain.) Not everyone, not even most people, have knee problems related to float or lack thereof. (I'm one of the lucky ones.) But for some people, float is essential to knee health with clipless pedals. You may be one of them.