When I lived in Regina, Sask. (flat prairies) in the 1970s, there was a strong West wind.
So I got my wife to ferry me to Moose Jaw to the west (about 50 miles away) and I rode back with that tailwind. I had no speedo, but I arrived home only minutes after my wife.
In those days, I didn't wear a helmet -- just a ball cap.
The wind blew it off and I chased it for a couple miles before retrieving it.