Did you PT give you good exercises to strengthen the muscles supporting your knee? You might check out Jennifer Rhodes book, Peak Performance Fitness. She's a PT and that book helped me a lot when I was recovering from a muscle imbalance (helped me more than the PT who was treating me for the problem). I'm glad you're seeking a 3rd opinion---I've found that some (not all) male docs blow off females, especially those of us who are athletic. Maybe they are like that w/male athletes, too? In any case, have you thought about seeing an osteopath instead of a orthopedist? Definitely get another opinion. You're smart to listen to your body. I hope you are back on your bike soon.