Generally speaking, I agree with what Phate's saying, but in my personal experience, I prefer the stationary bike.
Biking outdoors introduces all sorts of other elements. Suddenly you gotta have a trail to ride on, and pay attention to everything, so you're not falling headfirst down a hill or getting hit by a car. Weather becomes a factor (and maybe even an excuse
). Variables such as intensity, duration, etc. are harder to control and/or track. You also can't, say, watch a movie or occasionally check on your children while on a real bike, outdoors.
