I eat a bowl of cereal for breakfast whether I ride or not. I try to get the breakfast down at least 30 minutes before I leave or I sometimes get a bit of indigestion. Luckily my 13 mile (21 km) 50 minute ride doesn't have any major uphills in the first 25 minutes. I'm often ready for a snack by 10:30, but sometimes I make it til 11:30 and lunch. There is nowhere around my office to buy food, so I wouldn't want to have to carry breakfast and lunch on my bike.