My longer rides aren't usually longer than 40 miles(just started biking regularly this year), and I usually eat a good size breakfast a couple hours beforehand so I never have a hungry sensation on the bike. However, I do ensure I always have a small bag of trail mix in my handlebar bag just in case. On the rare occasion I plan on riding further (50+ once), I brought along a couple granola bars, but didn't touch them until the 35 mile mark. Again, it's better to have something just in case than to be stuck in the middle of nowhere, hungry as a bear, and not have any kind of munchies.