I haven't had knee replacement, my mother did, but she doesn't ride, never learned and at 86 I don't think she will ever start. Success though does depend on a few things, first is how good a condition you are in pre-op. Second is how good are you at following instructions, the medical team will give you specific instructions and exercises to do, to get you back to as close to optimum as possible, if you follow the instructions then there shouldn't be any reason why you can't. If you think it's stupid or too painful and don't do it, then it's going to be a lot less successful. Third is your age, at 50 it's going to be easier then at 75.

Tell your PT your a cyclist and want to get back to riding 50+ miles per day, they will make sure to tailor your recovery process to try to achieve that. Chances are they will get you on a spin bike/trainer as quickly as possible, as it's a good exercise that is low impact for your knees.