You probably are fit enough. However, from my experience, most indoor cycling instructors are just aerobic instructors on a spin bike. This is why I don't go to spin class very often; doing jumps and push ups on a bike in no way simulates outdoor riding, and right now, the gym I go to doesn't have a lot of instructors that are riders. So, I guess what I'm saying is that there are probably other people like me, who avoid classes that don't in some way replicate outdoor riding: hills, intervals, warm ups, cool downs. You can educate yourself without riding outside, but really, what is your husband scared of if this is something you want to do? Life is too short.