It shouldn't take more than 15-20 minutes to get warmed up and operating at full capacity. It seems like the simple answer is to try some different preride food that's higher in carbs, then see how it works. I need some caffeine to get rolling. Coffee and a Cliff bar would be my choice, plus some Accelerade during the first half of the ride. Rather than believe in what other people say and what they've heard, experiment on your own and see what works.