Ropers steam-powered bicycle still exists in the National Museum of the Smithsonian Institute of American History. As two extra wheels were used on this bike as stabilizers, the more pedantic amongst you will disqualify this vehicle as being a four-wheeler, but let's be fair; he didn't have a lot to go on did he?So that's it then..

There's a dispute, for eighteen years earlier in 1867 an American, Sylvester Howard Roper invented a two-cylinder steam driven motorcycle.However…