Several times i wonder if my fluid uptake is sufficient and what are the standards of the proper hydration. Normally i drink 200ml of isotonic drink in 20mins of ride in a cool air and more often in the summertime. Only rarely does it happen that i need to urinate after 2-3 hours of cycling though i don't feel thirsty. Does not feeling thirsty is a reliable sign of good hydration or a good fluid loading should send me behind the bushes every hour? In times when i have been compulsively drinking too much in order to fill my bladder i would feel an unpleasant balloning at my stomach that made my breathing more shallow..What about my riding buddy who is a lion on the saddle and refuses to sip a drop until we stop for rest-say 90 mins on-and even carries his bottle in his backbag!