The most your stomach can empty in an hour is 750ml +/- depending on what you drink. A 24-280z water bottle holds about that amount, so emptying a bottle during the ride is about as much as is feasible. If this is not enough it will take you a few more hours to make up the deficit. Calories should not be a problem in that short a ride assuming you have eaten reasonably in the several hours prior to the ride. Rides in higher temps (above 90F) can result in sweat loss that exceeds your ability to keep up but this would rarely be a problem in an hour. The over hydration hullabaloo has occurred in slow marathoners who take 4-5hrs to finish the run and drink "to excess" whatever that means. I suspect an adequate exam would show most of these people had some abnormality in their physiology which predisposed them to hyponatremia which is what caused their demise. As andygates says, most people just urinate off the excess in very dilute urine but will drop their sodium level to some degree, but not enough to get into a lot of trouble just from that alone. Steve