HI! this article might help http://www.ethiopianreview.com/health/201002/?p=146049

Total YES on learning how to energy yourself in endurance efforts. I can't drink straight Gatorade or something like gu when riding, my guts turn to mush. I only have water in my camelback(and start out well hydrated, this begins a few days/week before and you can't do this right before the event to "catch up"), I sip it all along the way and avoid dumping a large amount of water in my stomach at one time, which I hate the sloshing feeling too. I take dense/high calorie food--dried fruit(cut up into bits), nuts, PBJ sandwich I eat by the bite, and a Snickers bar for bonking(emergency). I like the dense food, it's small volume doesn't feel like anything in my stomach, and I nibble all along the way so there's never a lot of stuff in my stomach that sucks energy for digestion and I have a steady trickle of stuff going through to keep energy up. The trail mix combo also has carb/fat/protein--you need that balance.

How I eat in the morning and supper(after, during recovery) makes a difference too. Best breakfast is yogurt(1 cup) with granola(1/3 cup) and a cup of oj. At least an hour before leaving. If I haven't pooped(sorry) a cup of strong coffee to get that over with. At the end of the day I first either drink a big glass of milk or a hunk of meat and a big cold drink, then dinner has a nice hunk of protein and carbs like beans, big salad, lots of water. Then I have all night to absorb that, digest it, store it, recover for the next day.

This is what works for me, your mileage might vary. THis is what I've done both riding the dirt bike 90-100 miles of trail a day over several days, and several days of 75+ miles of bike touring(which I don't like to stop and fart around during).

Keeping the brain sharp and focused so you can make good technical decisions is something people kinda forget about too, while they focus on power. Keeping your brain alert also makes a huge difference in attitude, if you keep up your grrrr you're able to pull stuff out of nowhere when you think you've got nothing left to give.

But all of this is not at peak effectiveness unless you've done the homework to teach your body to burn the energy more efficiently--ie your cardio is fit as possible, more volume per stroke.