Hmmm,what was the outside temperature? Did you weigh yourself before & after the ride to see if you were dehydrated? I suspect you weren't.

Yah, sounds like electrolytes, bars don't have enough. You sweat away 600-1000mg of sodium per hour, eating around 500mg/hr should be enough to keep yourself stocked up. There's also potassium and magnesium to maintain as well.