just beginning to put together a single speed using a Super Course frame (year unknown but the almost gone decal says 531 plain gauge, frame is "coffee" and SN on left dropout is 204500). No previous parts to use as "templates".
The seat post ID measures 1.05 inches (thanks to my new Mitutoyo calipers). So, should the seatpost be 26.6mm or 26.4mm? Thank you for any experience and/or wisdom. Oh, and is the SN significant?