I find that spin class or spin on my own is a great sub for outdoors. Elliptical bothers my back (bikes don't) and other stationary bikes are boring to me. Rowing is a GREAT cardio and if done properly, you'll really work your legs. I'm impressed with your drive to get out riding so often; by the time I get home from work, I don't have enough daylight left! weights don't beckon me and I have to force myself to lift at least once/week