I am not a dietitian. If you have special dietary restrictions, ESPECIALLY related to sugar, don't listen to me. Talk to your doctor.
I'm going to make the case for eating more carbs before and during a long ride. Not hiking food, or backpacking food - riding food, which is high in carbs. The rule of thumb on a ride is "drink before you're thirsty, eat before you're hungry." I'm posting some useful links below, but as a rule of thumb: Don't eat to the point of discomfort. We're talking normal portions.
Dinner the night before: whatever you have, add carbs - pasta, potatoes, etc. Breakfast the morning of: a bagel, a pancake or two, some oatmeal or a muffin, etc. On the ride: raisin bagels, leftover pancakes, fig newtons, energy bars. To drink: plenty of liquid (a bottle an hour), both water and sports energy drink.
Before I joined the Stanford team I'd never ridden a real bike, so on my first long rides I didn't eat well, and I bonked repeatedly. "Bonking" is when your body doesn't have enough fuel to feed your brain in real-time. Your brain starts shutting down - you get sleepy, light-headed, feint, etc. It's misery. Your body has two calorie-rich sources of fuel - fat and carbs. Fat has the most calories, but your body can't burn it fast enough to fuel your brain on fat alone. You need at least some carbs. On average, you have enough carbs in your body (without eating) to ride for 1.5 hours. Eat carbs the night before and you get a boost. Eat carbs for breakfast the morning of, you get more. Eat carbs during the ride, even better.
The theme is, easy-to-digest fuel. Breads, energy bars, fig newtons ... easy to digest. Course multi-grain bread, raw vegetables, nuts ... not so easy. Be kind to your body on a ride. Give it what it wants. It wants carbohydrates, believe me. What about fruit? Fructose needs to be absorbed through the blood, which takes longer than simple sugars which go through the stomach wall. So eating fruit makes your body wait for the fuel it wants. And fruit is high in fiber. Your body is stressed. It's pedaling a bike for hours at a time. If you force your body to choose between riding your bike and digesting fiber, it will abandon the digestive process. And you will be racing for the nearest bathroom in extreme discomfort.
What about protein? Protein takes a lot of energy and water to digest. Eat protein the night before (with your carbs) and grab some protein during lunch. But you could skip protein and eat pure carbs and you'd be fine. Eating pure protein and skipping carbs is a recipe for disaster.
If you find yourself bonking, and you can't pedal another minute, do what every cyclist does - eat a snickers and drink a Mountain Dew. I can't tell you how many times this year riders have gotten to the half-way point of a ride, and not had enough energy to get back. I have them eat some sugar and drink caffeine, and they recover miraculously. This isn't in keeping with Hazon's general dietary recommendation, but if your body is shutting down, you do what you need to do.
But Hue, you say, we're not racing. That makes eating even more important. Our bodies aren't used to long exertion like racers are, and we haven't trained ourselves to burn fat at higher heart rates. So we need carbs even more.
Food for bikes redux
I have written before about my favorite energy bars for cycling. I thought I would share here another great training tip from Hue Rhodes who is an outstanding leader in the Hazon NY Ride executive committee with deep previous cycling experience. I love Hue's comment about "Hazon's general dietary recommendation", referring (I assume) to the generally negative press processed foods and sugars get on Hazon's jCarrot blog.