Nathan...I was also 260lbs about 2yrs ago, now 175lbs. The reason for my weight loss is about 12000 miles of cycling in those 2yrs. Initially you will find the cycling hard and tire easily, try not to get disheartened, you will find increased energy quite quickly. The weight will start to drop off rapidly at first then slow. Sometimes you will plateau and not seem to be able to loose more, but usually it takes a big effort or a special goal (like doing a long sportive) to kick start the descent below. Do set yourself goals and challenges as it gives something to work towards like riding a metric century (100km), then going for an imperial century (100miles).
I would advise not going mad on the diet, as most people fail at diets as they feel cheated of the nice things they like. Just eat sensibly, with enough to fuel you for the rides. Portion control is the key to loosing the weight. Have the stuff you like, but try and make it healthier (like having lean turkey instead of beef, cutting the fat off, not having full sugar soft drinks, but diet one's instead etc...) but just have slightly smaller portions. One thing that really worked for me was having a well stocked fruit bowl, so that when I got hungry and was tempted to snack in the biscuit barrel, I would have a piece of fruit instead, or drink a pint of water.
Well done for getting out there and making the change.......apart from marring my wife and the birth of my children, my weight loss is the single thing I'm most proud of in my life, as I've struggled with being overweight all my life......wel not any more.
