Note: Of course the answer is "ask your doctor"
I have, many times. 10 days ago I had arthroscopic surgery, partial meniscus removal, from playing tennis. He's very clear that it will be 6-8 weeks for tennis, due to the side to side torque.
When I ask about getting back on the bike, I get no real answer. He says bikeing is good for the knee, but falling isn't. I don't feel ready yet..but close. Do any of you have any experience as to how long it takes to get back to riding, and at what intensity?