A common number might be 200-300 calories per hour. How much you really need depends on the duration of the event, how well your body was "charged" with glycogen going into the event, how much food was left in your gut, and personal variations in how much glycogen you body can store. Only trial and error in both the quantity and type of calories will determine what works for any given person.oroy38 said:How many calories you take in is up to you. I've heard calculations like 2 calories per pound of bodyweight on the bike per hour with 1g of protein per 10lbs of bodyweight per hour in the early and middle segments of the bike leg. I've also heard of people sticking to a solid number.