Edit: 30.6mm= 1.2047244094488 Inches
as per notification below..
kind of weird then .. OP might check their accuracy of measurements ..
seems Bike frame tube diameters are traditionally fractional.. 1", 1.125". 1.25" etc
[French exceptionalism not withstanding]
though the threads and such are usually metric.
Last edited by fietsbob; 07-17-13 at 04:11 PM.