Originally Posted by
deep_sky
If you aren't feeling light-headed or faint, it could just be muscle fatigue. I did a ride yesterday and the last 5 miles of light rollers I pushed as hard on as I was capable of doing. When I got back to the parking lot, I got off my bike, and I had to do the bent legged thing for a few seconds before I could stand upright and start putting my bike and gear away. Were you working really hard on the ride or just moderate exertion?
I was working pretty hard (for me) and I did not have access to water for 30 minutes prior to event in question. I felt pretty thirsty.