Anker was a producer of vintage motorcycles from Germany. They’ve been known under different names (such as PAMAG and Bielefeld), but the brand itself has always been called Anker. The real bike production began in 1949, and it ceased in 1976 when the company was discontinued.
This brand’s history may be confusing, seeing how they changed names and the specter of work so often. Before their bike enterprise, they’ve been a bicycle producer and a sewing equipment manufacturer. That’s why they are now often confused with Anker Rotterdam – a lighting company. But they are not the same thing.
Anker’s logo history is very obscure. You won’t find any solidly official logos before 1949, and even after that your search won’t be very fruitful.
During this period, the company used several one-offs until they decided upon the final design used till their death. It was a simple ship anchor (the brand’s name is ‘anchor’ in German) surrounded by a circle. The color might change, but most of the time it would be either black or blue.
They most likely chose it somewhere in the 50s, but it can’t be proven.
The logo used by Anker Rotterdam usually appears when you Google Anker’s logo, but it was never theirs. The brand in question is German and never had any property in the Netherlands.
There’s much more info on bike emblems, however. The logo used by the majority of their moto-products was a big golden medal with an anchor symbol in the middle. Various words (mostly ‘Anker) were usually located on the rims. There is evidence it was even used sporadically as an official logo, maybe as a predecessor to the last design.