Originally Posted by
Chuckk
Since everybody is guessing, I'd propose that the root main cause of failure was an overshift.
The chain went over the big gear, dragging the derailleur into the wheel, where it hung up on the spoke long enough to stop the rear wheel and peel the tread before it popped the spoke out of the wheel and bent the hanger.
I've had similar things happen twice to me in the last humpteen years. Once on a bike I was test riding (seller had not set the inner stop screw on the derailleur he installed) and one that I built and just messed up.
Great observation. Also - of all of the components on a vintage bike, rims are the one that can be swapped without in my opinion on taking away from the bike. Lots of aluminum rims from Mavic, Ambrosia, or Velo Orange can be purchased without IMHO causing the look of the bike to be altered to a state where I would no longer consider it vintage. Except for brake pads, cables and bar tape, rims are the next item on things on a bike you should plan on replacing a few times in the life of a good bike.