It may or may not be known by a more elegant name Bike Rodeo. :-) This creation from Cyclecide allows two riders to spin the merry-go-round by pedaling the bikes. "The riders must be within 20 pounds of each others' weight!" warns a sign. "Rider assumes all risk!"
A 25-second video clip of children pedaling the merry-go-round can be found here on YouTube.