FWIW I found biking terribly aggravating for RSI. It really is not an ergonomic position. I'd recommend nearly anything other than biking. Swimming, weight lifting, basketball, etc. Anything where you aren't still sitting.
General gym workouts help, so long as I use weights and machines with care. But I have gone back biking after forgetting about the wrist pain, only for it all to come back and become chronic again.