I work out equally hard on the fancy LifeCycle in the gym as I do while road cycling. The LifeCycle machine says I'm burning more than 900 calories an hour. That's close to Cycling Magazine's formula which says I'm burning about 1077. But when I enter my stuff into FitLinxx, it coughs up a paltry 604.
Stats: 204 lbs, 18 mph sustained, altitude 940 ft.