Michaux-Perreaux steam velocipede

Motoring author L. J. K. Setright commented that, "the simplest way to define a motorcycle is as a bicycle propelled by a heat engine; and if we accept this we must go on to admit that its prototype is unidentifiable, shrouded in the mists of industrial antiquity."^[2] Both the Michaux-Perreaux and Roper machines have been assigned years of origin of 1867, 1868, and 1869 by different authorities, and which combination of these three years is given to the two steam motorcycles determines whether it was a tie, or whether one can be called the first.

Both steam cycles are rejected as the first motorcycle by other experts, such as Cycle World's Technical Editor Kevin Cameron, who either argue that a true motorcycle must use a gasoline internal combustion engine,^[11] or that the first motorcycle must use the same technology as the successful motorcycles that later went into mass production, and not a 'dead end'. They therefore give credit to Wilhelm Maybach and Gottlieb Daimler's 1885 Daimler Reitwagen.^[8]

After the period of experimental steam and internal combustion motorcycles, the uncertainty dissolves on the question of the first production motorcycle. The 1,489 cc (90.9 cu in) liquid cooled four-stroke Hildebrand & Wolfmüller of 1894 was the first motorcycle produced in quantity and sold commercially.^{[6][11][12][13]}

The earliest year suggested for the Michaux-Perreaux steam velocipede is 1867,^[2][3] which could be either the same year, or earlier than the Roper velocipede, which some authorities also date as early as 1867,^[14][15] while others such as motorcycling historians Charles M. Falco and David Burgess-Wise, and Motorcycle Consumer News design columnist Glynn Kerr date the Roper later, to 1868,^[3][8] and the AMA Hall of Fame member and author Mick Walker have it as 1869.^[16][17] Walker also dates the Michaux-Perraux at 1869, declaring a tie.^[17] Louis-Guillaume Perreaux patented his steam velocipede on December 26, 1869,^[1] while Roper did not seek patents on any of his steam vehicles,^[8] and Daimler took out a patent for his Reitwagen on 29 August 1885.^[17] Classic Bike editor Hugo Wilson says because the Perreaux-Michaux has patents to verify its date, it has a stronger claim on being first than the Roper, even if they both probably appeared in about the same year.^[18]

The Oxford English Dictionary and others include having an internal combustion engine as a criterion for a motorcycle.^[7][15][19] This definition of motorcycle worked for nearly the entire 20th century until electric motorcycles grew in prominence and were accepted as true motorcycles without question.^[8]

A different tack in favor of the internal combustion Reitwagen is that it was the prototype for virtually all successful designs that followed, in so far as the powerplant is concerned. Cameron said, "History follows things that succeed, not things that fail."^[8] Since all scientific theories and technologies are superseded in time, this kind of presentism dressing itself up as wisdom disqualifies itself from serious consideration. Design columnist Glynn Kerr, ignoring the Michaux-Perraux altogether and championing the Roper, feels it would be more accurate to call the Daimler Reitwagen, "the predecessor of all gasoline-driven vehicles on land, sea, or air", but not a true motorcycle because it used two outrigger wheels to remain upright and could not lean.^[8] Further, Kerr notes the design was not up to the standards Daimler and Maybach's engineering skill, because they had no interest at the time in motorcycles, but only wanted an expedient test bed for their engine, and immediately dropped the Reitwagen in favor of a four-wheeled stagecoach, a hot air balloon and a boat for their ongoing research.^[8] David Burgess-Wise called the Daimler-Maybach test bed "a crude makeshift", saying that "as a bicycle, it was 20 years out of date."^[3]