:The OED  gives this quote: "1970 Cycle World Oct. 34 Suzuki's entry in the ‘*Superbike’ field just happens to be an excellent touring bike."  Over at  google books the term pops up all over the place after between 69 and 71.  Here  and here are examples of sources saying the era of the superbike began with the CB750 four.  It would be nice to find out exactly which magazine first use the term applied to a motorcycle; it seems to have been commonplace by 1970.The Kawasaki Mach III was introduced a month earlier than the CB750, and could have (but wasn't, apparently, for whatever reason) called "the first superbike."  The Triumph Trident and BSA Rocket III also went on sale before the CB750.  Yet the British machines, for all their performance and good sales, are seen now as the last gasp of a dying industry, seeming to be a 1937-era Triumph twin with another cylinder grafted on, while the Honda was at the vanguard of a new era that has remained with us to this day.It wasn't that the CB750 was the fastest ever, or the first four, or even the first transverse four, but that it was practical, reliable, cheap and could be delivered to the public on a massive scale.  The disc brakes were a production bike first. (See Classic Japanese Motorcycle Guide pages 76-79).