I'm not an expert on cycling, but I've been playing roller derby for a decent amount of time (and it's a fairly intense endurance sport, thankyouverymuch). I try to eat as close to the earth as possible and throw vegetables into everything. If you cook already, try to incorporate vegetables into meals you already make. Spaghetti with meat sauce is easily kicked up with spinach, mushrooms, onions, and whole wheat pasta or spaghetti squash for a base. My recent mission is figuring out homemade energy snacks for the road. Gels / gummy junk / etc. don't do much for me and are expensive. I like almonds and a box of raisins, but it'd be nice to have a few more road-stable options (something that won't explode / leak everywhere when I'm riding).