I take on for every 100Km ride and will consume is at about the half way point. Unless I feel I need 2 or, feel I need a kick in the pants.

I always eat a bagel with peanut butter before I head out, and then I'll eat a Cliff bar somewhere along the way, a GU pack, and probably down a Gator aid while at a stop. That's my general routine, however everyone is different.