Interesting bike!

Hmmm, I checked out the listing on that auction site and saw the engraving on the cranks of "Ken Winkie" and "Eisenmann"

A quick google led me to this page: https://www.sfomuseum.org/exhibition...-1950s/gallery, some of the text of which reads, "Ken Winkie (far right, wearing a hat) imported Dürkopp bikes and was very active in the San Francisco Bay Area bicycle-racing community in the 1920s–1940s"

Further searching on Durkopp bikes, revealed this post right here on BikeForums that seems to have the same distinctive headtube lugs as your specimen (though many of the other details are different).

https://www.bikeforums.net/classic-v...-duerkopp.html