Take your pick. If you are not adverse to steam power, then Sylvester Howard Roper’s 1867 steam powered two wheeler is the world’s first motorcycle.

Otherwise Gotlieb Damiler gets the honor with his 1885 internal combustion engine powered vehicle—even though with outriggers it is not strictly two wheeled.

Frankly, I don’t care much either way. I’m just thankful we have advanced a bit beyond those early models. Hell, I’m glad as all get out that we are far beyond 1950’s technology which is when I was first wowed by motorcycles. Here are some links about the early pioneers: Motorcycle.com, uh.edu, Steve’s pages