Originally Posted by
Chuckk
One of the frame building books I've read suggested rolling the top tube to see if it was arched, and marking the high side if it was, so that you could miter so the arch would be up.
(Maybe Paterek, but not certain) So, arched tubes may be more common than we think.
First generation Cannondales were famous for it.
yes, not all tubes are true. With a bike that one acquires well into its life, there can be any number of things.
custom by crash. ( check the “as built” geometry ) here I would look for a very slightly steeper Seat tube and slightly shallower headtube.
think roof rack mounted bike meets garage header.
as built condition, at least the bow in not lateral.
Steel is quite tolerable of... enduring stress and still working.