My husband and I were dropped by a skater today, during the flattest portion of our 36 mile ride. There were a few hills in this part, but it's not as hilly as the rest of our route was today.
I was using the skater as a carrot, but didn't get close. I maintained 20-21 mph for a little while.
The guy had impressive speed. He wasn't in focusing range very long for me to read roadskater.net on his jersey!