My wife had a knee replaced and has recovered far beyond what was predicted. She rides lots of miles when she wants, goes to spinning, and hikes. What made the difference between her and the normal person was her determination to heal and the willingness to do the painful pt that was needed. When she finished her pt, she went to the gym and hired a trainer to specifically work her legs and focus on building her leg back up after years of atrophy. All the effort and sweat and pain paid off. Oddly, I know quite a few people who have had knee replacements and none have had the same results as my wife, but none did the work she did. They mostly followed the pt plan then stopped when the prescription ended. She took it to another level in order to be able to do all the things she had given up, except soccer and skiing, which are no longer options. Good luck with the surgery. Then do the work and you'll be back touring. Just know that it doesn't come quickly.