Well, as said above to lose a pound of fat, one needs to burn up 3500 calories.
Diet and exercise works well for me. Some people if they diet, their body responds by lowering its metabolic rate with the result of very little weight loss.
Another thing that happens in diets is people lose muscle mass and not fat or both together.
If you diet and exercise, you are more likely to sustain your muscle mass and lose fat. You can even get an impressive difference in your looks without losing much weight at all. Muscle is a lot firmer and better looking than fat.
Do not expect to burn all that much in the way of calories riding though. Bicycling is one of the best activities for burning calories known but even so it takes a lot of miles. It takes something like 70 miles for someone your size to burn off 3500 calories and that is assuming you don't eat a whole bunch after doing it. It is natural to eat a bunch after a long ride so that even sets things back some.
Now a rule of thumb on weight loss is that losing any more than a oound a week is not a good thing. The notion is that you want a lifestyle change that keeps you from gaining everything back. You are not really going on a diet as much as changing your lifestyle.
One thing to do is examine your diet carefully. Cut out as much of the junk and fat as you can. A good way to do that is to get a reference which tells you the calories and grams of fat, protein and carbo in everything you eat. You will learn to avoid certain things as just not being worth the calories. A little indulgance is fine but it is far to easy to kid ourselves about the calories we are consuming.
Remember our culture is against you. We live in a sedantary society and we also live in the land of the Big Mac (lots of high calorie foods which are yummy and readily available).
Good luck to you