My second pick is the transverse inline-Four Rondine of 1923, developed by fresh-baked engineer grads Carlo Gianini and Piero Remor. They knew that thudding along on one cylinder wasn't high-class, but they also knew the problems of the Belgian FN motorcycle, with its smoother-running inline-Four set longitudinally in the frame. First, its length made it vulnerable to "the dreaded side-slip," and once it got away, it was very hard to retrieve. (It rains in Europe, and city streets back then were paved with horse manure.) Second, natural air motion made the FN's rear cylinders run too hot. So, the two engineers turned the engine across the frame, creating the short wheelbase riders enjoy to this day while giving all cylinders equal access to cooling air. They kept scaring up wealthy sponsors until the whole show was bought by Gilera, which had the clout to make big things happen. Gilera Four became MV Four became Honda Four, and here we are today.