I want to second (or third) the suggestion about the recumbent bike. One of my friends here, a woman, was injured while running (by a car) and rides a single as well as a double with her husband. They are incredibly fast on that thing! If you would like me to put you in touch with her, let me know privately and I'm sure she'd be happy to talk to you about it.
The bicycle is the most civilized conveyance known to man. Other forms of transport grow daily more nightmarish. Only the bicycle remains pure in heart. ~Iris Murdoch, The Red and the Green