Supposedly, if you've been doing Paleo long enough, your body adapts to doing endurance exercise on limited carbs, running strictly on fat.

Not me! My body never adapted well. I had epic bonks an hour into any ride. That horrible feeling of wanting to yak half-way up a climb. Having to lean over the handlebars and breathe heavily for five minutes while the stars swirling around my head subside.

I had better results with carbing up near the ride and going strict the rest of the time:
http://www.amazon.com/The-Paleo-Diet.../dp/1594860890
http://www.trainingbible.com/pdf/Pal...liff_Notes.pdf

-- gnat! (Gotta really like sweet potatoes, tho!)