One thing I've found that works well for dropping weight is building muscle. There are lots of scientific explanations as to how muscle requires more calories (energy) to maintain than fat, but you'll feel it as you do it.
So, related to cycling, you'll want to do some hill work. It'll build your quads and glutes (your biggest muscles) and that'll require more calories to maintain. So, as long as you eat a healthy diet and don't over compensate for the increased burn, you'll drop weight.
Getting rid of your gut might be tough. You need to attack it from more than one angle. So, along with cycling, add some stretching, walking, and increase the quality of your diet (I've heard that's at least 70% of the results.)
See Tim Ferriss' blog about dropping fat:
http://www.fourhourworkweek.com/blog/2007/04/06/how-to-lose-20-lbs-of-fat-in-30-days-without-doing-any-exercise/
It's inspiring.