Originally Posted by
FrenchFit
It depends on your weight and other variables, but most calculators will probably tell you it's more than 1400 for two hours @ 12-15mph. Spin class is typically advertised at avg. 1000 calories per hour, but you are doing intervals there. But..it's not as much burned as it may sound. To lose a pound they say you need to burn something like 3500 over your daily maintenance, ..that's alot. That's why lowering intake is essential.
Just exercise won't be enough - plan each day for a calorie deficit, using your riding to provide part of the deficit and trimming meals a bit as the other part. However, be careful lest you go the other direction - riding making you hungry so you eat more. I find protein right after the ride helps kill my appetite.