Hammer Perpetuem. Quality ingredients and easily digestible. I simply would not take in enough calories otherwise. And for me, on endurance rides that include overnight riding, I DEFINITELY did not eat enough after the sun went down before I started using Perpeturm. Without calories in my bottles I would not be consuming enough.

I also like Gu Brew if I want carb-only drinks. (Perpetuem has some protein, which I prefer over an all carb drink on endurance rides.)