Multi hour ride nutrition
Informally, I find that on long rides, your body will simply know what it needs. You pull off at a stop; the trail mix and pickles look delicious, so you eat them.

More scientifically though, your body can process about two servings (e.g., bottles of gatorade, gel packs, etc.) of carbohydrate per hour. Any more than this, and you can experience gastrointestinal distress (politely put) as the excess carbohydrates back up in your gut. For this reason, I prefer to drink water on long rides, and use food or gel packs to replenish salt and sugar. This way I can decouple hydration from my carbohydrate intake — if I'm parched, I'm not stuck with the choice of getting dehydrated versus consuming too many carbs.

But first and foremost, listen to what your body tells you it wants. Drink plenty of water and try to spread out your consumption of food and drink evenly. Lots of small snacks will be easier on your digestive system and keep your energy level even, as opposed to a few large binges.