Originally Posted by mud
No, you were clear.
My answer is the first one. To tell if a specific tubeset is 531, cut it apart and destructively test the tubes..... You can figure out if it is columbus by show it to an old school builder. As stated above.
The pictures were to help if it was a production frame, we could figure it out.
Thanks. I'm very curious how one might tell from a few photos what type of tubing is used. Are there any links to this process? Here's one.
Has anyone here actually seen bare 531DB main tubes??