All the big names had the equivalent of Bianchi Formula Columbus tubing - butted frames of unknown specification.

While you can't tell SL from Champion 2 with a caliper, you can tell the center and butt thickness difference between SL and Cromor. The water bottle holes give us access the the center wall of the down tube once you account for paint. And you may get some okay butt dimensions from the inside of the BB or head tube.

Has anyone tried this?.