Supposing you have a frame without any Reynolds decals (transfers). No chrome on the frame. You know it's made of either Reynolds 753 (you're pretty sure it is) or 531. How do you tell the difference? The seatpost diameter is 27.2 which indicates 753, but I've been told 531 frames had 27.2 seatposts too. Or is the difference in weight and ride only? Or is it really visually different? Thinner I know but visually that much thinner to distinguish?
And when, exactly, was 753 introduced?? Many sources say 1975 but the Reynolds website says 1976 which seems later than even I remember it.
Peter Kohler
Washington DC USA