Having been armed with the info on how to date my Rotrax I finally decided there was only one way to find the frame number. The bottom bracket shell now has a large ammount of the paint removed, courtesy of a 3/4" wood chisel, and I have a 1950 rotrax, frame number 50514. The number is stamped on the underside, round the shell next to the lockring on the left hand side of the bike. All I need now is to find out what model it is.
Any help welcome.
Russell Mowat