Water and lots of it of course but only other drink supplement when riding for me on longer rides is Cytomax. Didn't do the science, just know it keeps me going and makes the post ride better too....all that matters to me. Cliff bars and edible stuff better suited for discussion about ride food, not sports drink. With a bottle of Cytomax and 70oz of water in the camelbak, I'm good for 5 hrs of riding of whatever type in whatever weather or conditions which is longer than my ass wants to be on the seat but that's another thread too.