Hildebrand & Wolfmuller motorcycle books include the history of this German motorcycle which was the first powered two-wheeler to enter series production.
In 1894, the Hildebrand & Wolfmüller was the first production motorcycle that was available for purchase. In 1889 the Hildebrand brothers started by making a prototype motorcycle using with a small steam engine before joining Wolfmuller. Together they designed a twin cylinder, water cooled, four stroke motorcycle.
Die Braunschweiger Hildebrand & Wolfmüller: Das Erste Serienmotorrad Der Welt by Jan Spies (1988) German text