I just recently started mixing in G2 Gatorade (grape flavor is the best for me) with my water in my camelback on a 1:1 ratio and I can't believe how it has helped on the 15+ mile rides. Training helps as well, but I am finding that nutrition is so important. I was always afraid to make my stomach upset and puke. I just avoid eating 1-2 hours before the ride and not stuff my self. The more fatty and high acid content the food is, the worse it is for me. I avoid spicy suaces, fatty foods like potato chips, mexican food, etc. The best I have found is a well balanced sammich like mentioned above. If I ate pizza right before a ride, everyeone would see what I had for lunch.
One of the things I learned from a fitness instructor is that it is important to recognize glycogen stores. I am no expert, but from what I remember, she said that the average person can store like 90 minutes of stores and people in shape can store up to 115minutes. It takes about 2-3months of regular exercise to get the body to increase storage. She said that these stores are good for normal activity, not continuous strenuous activity. As activity increases, the time can go down for many people. She explained this is why so many out of shape people "bonk" on longer events like half marathons, longer distance cycling, etc. Basically anything over 1-1.5hours and you need to replenish your body and fill those stores or burning and cramping will set in. If you aren't eating properly to start with, your stores of glycogen probably aren't full to begin with. Maybe I have it all wrong, but I think that is what she was explaining.
