2 hours of stationary biking = how many calories?

[Ns1]

So I'm trying to do some planning for the year and I had this question:

I'm looking at this chart and the calorie counts seem VERY high
http://www.nutristrategy.com/caloriesburnedcycling.htm

If I sit on a stationary bike and bike 30-40 miles in 2 hours @ 0 resistance, is that really 800+ calories burned?

 

[RichieZ]

edit: at zero resistance on an stationary bike as used in a spin class then the answer is no. most of the indoor bikes have a power meter or an approximation of a power meter based on the known characteristics of the flywheel attached to the bike, so you can directly measure output

its not unreasonable to burn that many calories if you are acutally biking at a decent clip. ex my ride to work:

and if you are doing intervals on an indoor trainer you can burn a fair amount of calories:

 

[_Rick_]

It all depends on how many Watts you can put out via the legs in that time.
And whether the stationary cycle can take those Watts.
A spinning bike is really only good to work on form and short intervals. Same for rollers without brakes.
A decent trainer will be able to take a few hundred Watts though, and currently in the flat, I'm able to put in around 200W average over 90 minutes, if strava's calculation is to be trusted. Know your power output, and you can estimate your required calorie input to maintain it.