I get a headache about an hour or so after completing a hard 2-3 hour ride. I suspect it is from a low blood sugar level. About an hour before an early morning ride I eat a good breakfast and at completion, I eat a couple of PP&J sandwiches with a 32oz. gatoraide. This seams to work for sub 2 hour rides but not the long ones. I am going to continue the above and in addition, eat an energy bar right before the start of the ride. Maybe it will enter my blood system by mid-ride and not allow my sugar to drop causing a headache. Does anyone share this problem and is my theory correct?