Thanks for all of the great information, and good luck patentcad!

I'm 58, and managed to ruin my left knee. I was thinking it was all the hill climbing, but I also used an elliptical stair master for years. I think that may have helped with the deterioration.

I have the TKR scheduled in December. The surgeon and his staff claim that I won't be able to do hill climbing without pain if I put off the surgery. I can ride without pain now, and have started back riding hills. I'm going to start getting up our local mountain (Mt Diablo) his week, which is a 7 - 8% grade climb. If I find that there's no pain from this, I will be really confused! I can't go forever without that surgery, but putting it off another year will be attractive. I have no ACL, no cartilage, arthritis & bone spurs. I've been doing physical therapy to gradually strengthen the knee, and riding doesn't give me any trouble.