On rides longer than 2 hours, I've had only water in my bottles and I eat Shot Bloks or similar products while riding; at rest stops I might eat 1/2 a banana and/or food bar (favorite is Trader Joe's "This Fig Walked into a Bar", or the apple version) depending on how I feel and what I've eaten so far. These have been fine for me at moderate paces in moderate temperatures, but I tend to run out of steam on the second half of group rides approaching 50 miles or longer --- which I've blamed on my being off the bike for all of 2011 and having not enough base miles this year. I'm working on building my aerobic and muscle endurance, and I'm wondering if I need to have a sports/electrolyte drink in one of the bottles on longer rides, especially group rides that are not self-paced when temps are warm.
So, my question isn't how but when do I drink it? Do I alternate between the water and electrolyte drink for the duration of the ride? Or, do I switch to the electrolyte drink in the second half of the ride, and drink just water w/food at rest stops?
Do you go by how you feel, or do you schedule your intake of these drinks at specific points in the ride?