+1 to sstorkel and others above who advocate a calorie-counting approach. If what you're doing isn't causing you to lose weight, then you need to get a little more scientific about it. Make a best estimate of your daily calorie needs for maintaining weight based on formulas/calculators online, plan to consume say 500 fewer per day, then track what you actually ate to make sure you stay under that number. As someone noted above, a deficit of 500 calories a day translates to 1 pound per week.
Try to estimate how many calories you are consuming through cycling and other exercise through formulas/calculators online, but be conservative (you want to underestimate rather than overestimate), and remember to subtract your base metabolism rate from what you burned (i.e. you don't get to take credit for what your body would have been using anyway during that time).
I found that my 9-mile round-trip commute was burning maybe 325 calories per day. When I learned that a typical donut has around 400 calories, I realized that giving myself permission to eat a donut after cycling was only going to cause me to gain weight. I think a lot of people fall into that trap. Exercise is great, but we need to be realistic about it. Now, cycling makes me want to eat less, because I don't want to negate what took me time and effort to achieve.
Some of these calorie estimates (what you ate and what you burn) will be scientific guesses, ballpark guesses, or even wild-ass guesses. Once you do it for a while, you'll figure out what you can eat and how much you need to exercise to lose weight. Maybe you'll lose a bit faster than you think you will, or maybe you'll have to aim for, say, a 700-calorie deficit.
I've lost about 17 - 18 pounds in a little over a year. I'm close to my target weight, so I'll be shifting to maintaining....