Greg's right. Most important thing is eating during the ride: don't get depleted in the first place. Second is carb replenishment after the ride. You're training for a race, but don't give us any idea how strong you are. However, you might assume that eating at Greg's suggested rate will replenish about half your calories. So that's your starting point. You want to eat pretty much pure carbs with a little protein during a ride, and then eat carb heavy after it too, including a little protein and fat. You can buy recovery drink powder for a good start. Read the label and then make your own if you don't want the expense. After maybe 300 calories of recovery drink, eat a good balanced, but carb heavy meal. Vegetables can also be carbs.

I rode a hard 66 miles in the rain on my single yesterday, and then today rode another 50 on our tandem. My legs felt tired when we started today, but we had plenty of go and were able to do high cadence hill accelerations, so I had something in the tank again. Yesterday, I ate 300 cal. for breakfast, 750 cal. on the course and recovery drinks and food for about a 1600 calorie total before dinner. Today I ate 400 for breakfast, 500 on the course and recovery drink and sandwich for about 1300 calorie total before dinner. I should lose a little weight at those rates. If you eat carb heavy, your weight is how you tell if you're eating enough to keep your power up in the long term. If you're also trying to drop weight but want to ride fast, don't drop more than a pound a week.