magrat22,

Probably you passed out because of a sudden drop in your blood pressure. You were working so hard and then you just stopped. Stopped cold without any chance for your body to recover gradually. When you are pedaling, your legs going round and round, the pumping motion of your legs is assisting your heart in pumping the blood through your body. When you quit suddenly, your heart doesn't have time to take over, your blood pressure drops precipitously and you black out. Did you ever see stars or feel dizzy when you stood up very quickly? Similar things, you just went beyond that point. What bounceswoosh suggested would keep you moving and let you recover bit by bit. In almost any sport, after a hard effort, you will see people cool down before they quit what they were doing. There's definitely a reason for that.

Don't let the hill get to you. Keep riding and eventually, you'll be able to conquer it.

annie