50-55 mph? We rode into a bit of headwind touring across Wyoming a few years ago. It took us five hours to ride 20 miles, including a top speed of 6 mph, pedaling, down a 6% grade. I didn't want to estimate the wind speed because no one would believe me, so I asked one of the hosts where we camped how strong the wind was. He estimated 50-55 mph. Since he had just come the other way with a trailer, I figure he had a good idea of how fast he was going. It took us a few days to recover after that!