Maybe it was a quality GECO or Habicht??? I've also noticed that at some point the position of the smaller crown on the underside of the right tube is occupied by the script intertwined "SuS". Another note is that Sauer tubes sourced by Carl Grundig, Ernst Steigledger, etc. typicall have the words "FLUSSSTAHL - KRUPP - ESSEN" followed by a vertical "Caveman" with a "Club" in a type of oval stamp.

The above example has the initial "M"(maybe mechanic's last name) adjacent to the "Caveman" with a "Staff".

Kind Regards,

Raimey
rse