The body has enough stored glycogen for about an hour and a half (maybe 2) if you are riding at a spirited clip. How much energy ou use will depend on how hard you ride. As long as you have a nice meal a couple hours before you start, and If you ride very slowly, you may just need water. If you ride a bit faster, you will probably want to have some snacks or energy bars/gels on hand just in case. Bananas, fig bars, some small sandwiches (no mayo unless refrigerated), or whatever you prefer. Running out of fuel 30 minutes from your destination will be no fun at all. Better to arrive having not used the snacks than to not arrive at all. Have fun!