Originally Posted by
JohnDThompson
Octagonal, perhaps? If it is a Stronglight bottom bracket behind that Stronglight crank, an octagonal fixed cup would indicate Italian thread:
Source: Sutherland's 4th Edition
Aha! I think octagonal is more accurate description (vs "regular nut"). Once crankset is off tomorrow - I'll inspect cups again closely and see if there are any indication outside.
I also think actual serial number is right behind seat post on BB, hidden by cable guide plate at the moment. I am still going trough all Bianchi CDI threads and one has very similar looking Bianchi (mostly frankenbuild but same looking RD, etc) and S/N is hidden by cable guide at the bottom of BB