How does bicycling compare to stationary bike for cardio purposes? I usually do the bicyling once a week if I can over various loops in my area of between 10 and 20 miles. The loops I do are a lot like hiit in that there are hills spaced fairly evenly and which take no more than a minute or two to climb. Then there is a short downhill where you can gear up and keep pedaling to the next hill, generally a couple of minutes away. One thing I do notice, I get a tremendous leg pump from this as well as a fore arm pump.

How does bicycling compare to stationary bike for cardio purposes? Your heart rate is what matters the most -- that's why people say to use whatever machine you want: skiing, stairs, bike, treadmill, etc.

Where I live (next to SDSU) there are lots of crazy drivers, so I ride the bikes indoors where it's safer :)

I like what Shawn Phillips ('http://www.musclemedia.com/training/hiit.asp') has to say
Of course, if you're content to do it the old-fashioned way and spend the better part of the day getting intimate with a bike seat and the rest of the day spreading baby powder on your chafed thighs, go ahead. Somehow, the idea of sitting on a bike and going nowhere is a little weird to me. It's like going into the garage and getting behind the wheel and pretending you're going for a Sunday drive....