On a ride last week, I'd been pulling at 24 for a bit over 2 miles when one of the guys sling-shotted past me for the final sign sprint. That's OK, I was leading them out on purpose, but I expected several guys to go for it. Since there was just one, I decided it was up to me to give him a challenge. He was doing 34 mph when I coasted up alongside him, made a show of hitting the brakes, and asked him if he had any Grey Poupon. He lost the sprint. They hate it when I do that!
I don't think I quite hit 40, though. I'll never know for sure because my speedo wasn't working. I just know my 53/12 was red lined.
Holding 40 mph, even in a group, is very impressive. Maybe they're running 56T or 58T chainrings?