Tom Cruise in the classic film 'Top Gun' may have had "the need for speed," but so have generations of motorists, particularly the ones known as bikers. Indeed, the motorcycle has evolved into the vicious, powerful, and awesome two-wheeled vehicle we all know and love today, but where exactly did it originate? What fuel sources did it rely upon prior to gasoline? And what exactly defines a motorbike? Find out in this week's truly sick episode!