Originally Posted by
TrojanHorse
The quality of your cardio workout is related to the HR you attain and the length of time you keep it there, which you can do on any bike. 99.9% of your cycling is probably aerobic, ergo - good cardio.
Nonetheless, your reasons for getting a road bike are solid.
I agree with the HR thing. I mash my pedals and turn it into a power workout. Cardio benefit isn't what it could be if I slowed down and spun. Maybe I could train myself to get my mph back up there but I've been a power guy my whole life and that's what comes natural. I'll have to fight that urge.