I'd add that you don't really need to stress too much about what you're bringing unless there are no places to stop along your route. Even on long rides, I usually just carry enough food to carry me to a place to stop. But I don't usually eat much at all during a ride unless it's more than 40 miles, as I prefer to eat what I will need before I go. An electrolyte drink and water will take care of most of your body's basic needs if you eat properly beforehand. You might also want to carry some sliced bananas, as they're great not only for energy, but to prevent muscle pain following the ride.