IMO riders should get some protein, but more carbs, for rides over 1.5hrs. Don't forget electrolytes. I used to drink Gatorade but it just made me more thirsty and I would get sugar rushes, then crashes. Screw that. I then tried Accelorade, then Cytomax's stuff...I forget the name.. then tried Hammer's HEED and have been using that ever since. For post-rides I use Hammer's Recoverite within 5 minutes of getting off the bike. I gotta admit, the sh*t works. OK, where's my damn endorsement goodies!
I hate paying the asking price for Recoverite but it works for me. HEED's pretty cheap in comparison to the other brands. Sometimes I get tired of the flavor, but a little white-grape juice added in takes care of that.