The major reason for my recent surgery was to be able to cycle ... I reached a point where my rides were more painful than not and that tipped it for me. I had several LONG and DETAILED discussions with my surgeon about my plans to ride 150-200 miles a week (that was my pre-surgery mileage) and climb often. I also read what scientific literature I could find about the wear on protheses among athletes who resumed activity after surgery.
My surgeon assured me that my post-surgery plans were viable, but he would check the prothesis and my overall condition more often than he would a less active patient to identify any issues that might come up from my activity level. And, I found some minor reassurance in the literature that folks can be active after surgery without too much worry about prothesis wear causing problems (I will have to find that reference again, it was a year or so ago I located it).
Anyway, my guess is that you are fine as long as you keep tabs on how you are doing. There are lots of us aging folks who are returning to higher levels of activity after TKR and since cycling has among the lowest loads on the knee, we should be fine! Keep up the good work!