Proper nutrition is the key to accomplishing the Dolomites Bike Day, where the 51km loop requires an average of 1,500 kcal.
Your breakfast before the event needs to be rich in carbohydrates, but do not overdo it if you're not used to big breakfasts, and plan to eat on the go in order to supply your body with adequate fuel throughout the day (bars, gels, electrolytes, and 'proper food' too!).