I've been looking into nutrition because as I've been doing longer rides, on bike nutrition and after ride recovery nutrition have become increasingly important. I'm just beginning to get a handle on aerobic and anaerobic energy systems. gdhillars's post reminded me of this. I'm not to conversant on this topic and we have an entire area devoted to training and nutrition. When I know more about what I'm talking about I am going to ask some questions over there. In the meantime, not depleting glycogen during the ride seems to be the key to endurance.