I was visiting central Germany [then it was West Germany]in 1952-3 and bought a Sigurd Kassel at a bicycle shop in Frankfurt. I rode it for exercise to balance my office job with the U S Army. I don't know anything about the company but it is a good road bike with a large frame that fits me better than the domestic brands, so I brought it home in 1953. The emblem is almost exactly the same as your picture