A Brief History of the Marque
Manufactured in Mühlhausen, the bicycle factory built motorcycles using Fafnir engines of 3.5 hp and 5 hp.
The owner's name was Claes Pfeil and possibly machines were also marketed under the Pfeil brand, as were the bicycles.
The original firm named Claes & Flentje was established in 1869 by Franz Theodor Flentje and Ernst Bernhard Claes, building sewing machines. Bicycle production began in 1889 and they built their first stationary engines around 1900, at which time the factory had over 1000 employees.
Bicycle production reached 300,000 pa by 1930.
Sources: Tragatsch p104, de.wikipedia.org, fahrradsammler.de.
N.B. In the 1950s there was a Pfeil by Sudbrack