Originally Posted by Richard Cranium
Wow, sounds like an "old-timer" discussion. Hey, I wonder if any custom-frame builders ever "mixed" different tubesets for certain sizes and types of bicycles?
I wonder what the numbers "8 5 3" mean on newer tubing?
At one time, I thought "tube numbering" had something to do with ANSI steel/alloy identification standards.
In the past makers used to mix tube sets all the time. The most common was the use of Columbus SP downtubes (heavier wall thickness) in larger frames of otherwise SL tubes. I suppose there was nothing to prevent using a mix of Columbus and Reynolds tubing in one frame but I don't recall hearing of anyone who did.
I'm pretty sure the tubing set numbers, 531, 725, 853, etc. are contrived labels having no relationship to the ANSI/AISI alloy family numbering system.