Allo Diavolo and the trick to riding a bike upside down

From today's "Strange but true" in The Plain Dealer:

Q: What's the trick to riding your bicycling upside down? A: Lots of centrifugal force along a loop-the-loop track, as performed by Allo "Dare Devil" Diavolo in a 1901 circus stunt, say David Halliday and others in"Fundamentals of Physics." Diavolo coasted down a long runway, building up speed until he hit the approximately 8.8-foot-radius loop, then up and over he went. Based on elementary physics, this figures to a minimum necessary speed for Diavolo of 16.8 feet per second, or about 11.4 mph, to prevent his losing contact with the upper loop and falling. This speed requirement was independent of the weight of Diavolo and the bicycle. "Had he feasted on, say, pierogies before his performance, he still would have had to exceed only 11.4 mph," the authors say.

Devil horn costumes obviously don't factor in, then -- or DO they...???