The 1937 Zundapp K800
Before the Honda Goldwing was made, there was the horizontally-opposed 4-cylinder engine motorcycle brought to life by the german company called Zündapp.
After the 1921 war, the company branched away from machine tool and armaments production, towards motorcycles. The Z22, also known as the "Motorrad für Jedermann", was the first motorcycle produced by the German manufacturer. By 1933, Zündapp had began making K-series bikes. These were significantly larger and considered ahead of their time because of the enclosed shaft drive.
The Zündapp K800 then appeared shortly after, and was a joy to drive due to its 798cc engine. At the time, thanks to its power, steel frames, and rugged grinder forks, it was the best motorcycle to have a sidecar along for the ride.