I strongly prefer Mountain Dew to Gatorade. When my two water bottles are empty (typically after around 50 miles, sooner if it's hot out), I'll stop at a gas station and fill the bottles with ice and pour a 20oz Mountain Dew into the bottles to top them off. It's watered down, obviously, and not very carbonated due to the sloshing that goes on--but MAN OH MAN is it better than sports drink.

I've been doing this for some time now and it works extremely well for me. I think the advice against carbonated beverages on long rides is a bunch of hooey marketing by the sports drink vendors.

--Steve