http://stanford.wellsphere.com/bikin...alories/236678

There is a link to an interesting article comparing the difference in calories burned between running and cycling. They say running burns 110 calories per mile no matter what speed they run, and that the calories burned cycling varies but is based on the riders speed. There are a lot of factors that go into cycling, no real way to quantify them all but if you are on flats with no real tail/head wind the article gives you a good idea.