I'm okay on just breakfast (or whatever) until the 25-30+ range (depending on what I've eaten, wind, etc). I definitely eat during rides--if it's 40 or less, I get by on a Clif bar (in cool weather) or Shot Bloks or those Honey Stinger waffles (those are good!). Above 40, I start needing more fat/protein than a Clif bar can supply, so I stop for real food, or I take almonds or beef jerky with me. I try to remember to eat every hour on longer rides. Doesn't always work, but I try.