I am also a cyclist, but I am not a gonzo cyclist. I do pretty gentle riding, though I can do some long rides -- they just take longer at my speed
Here's my story -- I had a pretty easy recovery and did mostly walking until...
3 1/2 weeks after surgery did a gentle neighborhood ride to check myself out. Did about 2 miles and felt that the pedaling and leaning forward did not stress anything. Cool
Biking actually was easier than walking -- much smoother.
4 weeks after surgery we went to the shore and did a LOT of walking -- probably about 4 to 5 miles on each of 2 days. This was tiring, but did a lot of lying around on the hotel bed, too.
4 1/2 weeks after surgery did a flat bike ride of 35 miles. This was probably insane, but I really felt fine. I had a lot of support and felt that I could ask for a ride back at any time. The whole ride with breaks probably took about 5 hours. The biking was on smooth roads and paths -- no bumps.
5 weeks -- I was back at work 1/2 time and at 6 weeks full time.
I am not a mountain biker, but even if I were, I would not have felt comfortable to do that kind of riding, since jostling was still a bit uncomfortable for several months.
My surgery was exactly one year prior to yours. By the end of May last year, I took a long weekend and enjoyed day rides with my friends. I think I did a 35 mile ride, a 22, and a 37 mile ride.
The rest of my summer, I was pretty much OK, though I think I needed more rest stops and early bed-times.
I think I was lucky to recover so well -- listen to your doctor and your own body. You'll know when you're ready.
Good luck and enjoy your bike.