I agree that it's just part of it, and not the most pleasant part by any means. The thing about cycling is that you're breathing from the belly and NOT using the abs for rotation the way you do with running or swimming - on the bike, your abs are pretty much completely relaxed, and that's not necessarily the prettiest sight from the side. Look at pictures of the pros some time. Body fat around 12% (women), and their bellies are still sticking out, because that's where their diaphragms are.

I think the bottom line is that you need to understand that you, looking at your pictures, are the only one looking at your belly from that angle. Everyone else is admiring your powerful legs.