I just read a whole shpiel on pre-event eating by Hammer Nutrition, in which they said: The first best thing would be to eat about three hours before the event. The second best thing, if you can't do that, is to eat about an hour after you start riding. They said, try not to eat just before you go. This is them, not me--but it was interesting reading. I'll try to find the "why" later and post that here too. They did have an explanation for it.