If you work out, you know how powerful carb cravings can be. Anything from ten hard minutes of lugging furniture up stairs to your new apartment to a solid ninety minutes of riding your mountain bike through the backwoods and trails of the hinterlands can trigger a chemical reaction in the body that makes you have carb cravings.
For me personally, I prefer the sit down exercise bike to any other type of cardio work out. It's actually not as effective or efficient as other work outs like jogging, swimming, and any kind of cross training, but it's low impact and easy to get to every day. If I want to jog or do a cardio kick boxing routine, or go swimming, then that's what I have to be doing. I need to pick up and go to the pool, or put a video on the tv and work out to that, or go for a bike ride. I can't just sit on my ass in front of the television and peddle til I get my heart rate going, then keep it there for a half an hour.
And that's what's great about the sit down exercise bike. I can watch television while I'm doing it. If I have a favorite show that I've tivo'd and want to watch, I can make it coincide with my cardio workout time. If I want to read a book, I can do that instead and make it coincide with cardio work out time. It's the lazy man's work out, no question about that, but it is, still, a work out, and one that I'm better off doing (or you're better off doing) than nothing.
And just like any other work out, it burns energy. And carbs are your body's fuel, which means you need to replenish when your work out is done. If you don't, you'll suffer from carb cravings and probably end up eating twice the amount of calories as what you've just burned.
For me personally, I find that I need to eat something containing both carbs and protein within thirty minutes of my work out or I'll get terrible carb cravings. Rice and beans are a good choice, since they combine to form a full protein, they have "good" fats instead of "bad" fats (saturated fats), and they'll provide you with both energy in the form of carbs as well as proteins which will help you build muscle. And as you probably know, even when they're dormant, muscles actually build energy. So it's a self-fulfilling prophecy, in that the more you work out, the more muscle you build, then the more energy you'll burn just by having said muscle.
So be aware of what your carb cravings are signalling to you in terms of what your body needs to fuel itself.