For example, the following activity charts says a person of 190 pounds who bicycles at 12-13.9 mph burns 690 calories per hour, at 14-15.9 mph 863 calories per hour, and 16-19 mph 1035 calories per hour. I pedal in the range of 14-19 mph, depending upon all of the variables, and I can tell you on a good day with a brisk wind and a lot of steep hills I might, just might, burn 500 calories an hour. That is how huge the difference is for me and what the charts say.
http://www.nutristrategy.com/activitylist.htm
Darcy