This sounds familiar to me [MENTION=564980]Tsch0e[/MENTION] , but, I have to caution, that even though my experience seems similar, it might not be the same root cause. When I started bike racing I did well with almost no training. Once I got off to a good start, training rides started to get more serious. As I trained more, I got slower. I thought the pain in my knees were just because I working so hard. I didn't think it was because of a problem. I finally went to the college clinic as the pain became constant and my knees would either lock up or give out. They diagnosed the problem as chondromalacia patellar. This condition is also known as "runners knees". I did some physical therapy, but things did not get improve.

Next stop, a orthopedic surgeon specializing in knees. They did an X-ray and had a machine to measure my knee muscle strength. This muscle strength machine measured an abnormal application of force that is typically seen when pain is involved. The doctor therefore came to the conclusion that I indeed had chondromalacia patellar. He explained that this condition is a result of a muscle imbalance. Normally they are in balance and the kneecap (patellar) tracks properly in it's groove. But when there is an imbalance the patella doesn't track right, this results the tissue on those rubbing surfaces becoming pilled like a sweater and pain.

He said there are two ways to improve this condition: We do an operation where we guess at how much this imbalance is and cut the stronger muscle just enough to try to achieve a balance or you can quit bike racing for now and do exercises to strengthen the weak muscles. Of course, for me it was the second option. I had already been doing physical therapy, so I continued to do it at home and the last thing is that by being sensitive to condition, I learned what activities helped and what made it worse. For me swimming, particularly breast stroke with frog kicks worked well. I also did resistance exercises that strengthen my inner muscles.

I think the next step is to see a Orthopedic surgeon. If you can find one that specializes in knees, that would be the best. They will probably set you up with physical therapy. You may need to spend some time off the bike. By the way, I tried all the fitting things, changing my petal stroke to pull up and none of these changes worked for me.

Please let us know what you find. This happens to some of us when we get more serious about doing more cycling.