If you're cycling, you should probably eat more than just one banana in a day. Even if you are not cycling, you should eat more than just one banana per day!
Best thing is to follow the USDA food pyramid and try to eat primarily carbohydrates with a modest amount of protein and minimal fats. Try to eat plenty of fruits and vegetables so you get your vitamins. For cycling, if you are cycling for less than an hour, you don't need to eat anything special before or during your ride. For longer rides, you will probably want some sort of carbohydrates like fruit, energy bars, Fig Newtons, trail mix, gatorade, etc. Eat something that you like to eat.