If iam bone on bone in my knee, is it alright to ride my recumbant bike and exercise?

Yes. With osteoarthritis, exercise that maintains the motion and strength of your knee can actually be beneficial in maintaining your function and decreasing your pain. This should include low stress aerobic exercise such as biking and progressive weight training for strength.
Good choice. Aslong as it dosent increase the pain or swelling, domt execise on a swollen knee if you have night pain at rest. A joint replacement will help.