Services for Owners of Classic Motorcycles and Automobiles in Germany
The GTÜ classic car service is a public information and archive system for classic vehicles which includes listings for all major and a good many more obscure German motorcycle marques. There are similar pages available for other European brands.
GTÜ Gesellschaft für Technische Überwachung mbH
Vor dem Lauch 25
Sadly, the gtue-oldtimerservice.de site is no longer online. Portions of the motorcycle section are available at the Wayback Machine.