Plot: Set the sedan’s safety brake and hop on your “hog” for a 2-hour high-speed history of the motorcycle–from the 1868 “steam velocipede” to the early 20th century, when they were a low-cost alternative to automobiles; from Harley-Davidsons preferred by Hell’s Angels and police to motocross riders who take bikes into the air and onto the dirt. We also look to the motorcycle’s future, featuring Jay Leno’s jet-propelled Y2K sportbike and Erik Buell’s bike-without-a-gas-tank creation