Daniel,
There are a number of members who have Sieber track bikes. I just
restored one and also went through the process of trying to date it. It
seemed to me that the only clue (unless you have Sieber parts) is the
lugs which seemed to get quite a bit fancier in the post war models. I
have pics from about 4 list members bikes soe if you send me a close up
of your head lugs I might be able to give you a ball park date. Ted
Earnst, however, I think is our Sieber expert.
Edward Albert
Chappaqua, NY