P.S.: I forgot to mention: The best bikes of Jo Routens used relatively beefy twin-plate crowns in conjunction with brazed-on brake pivots well into the 1960s, with no record of numerous failures despite many of these being ridden in the mountains. (Of course, to be devil's advocate, Routens built many less top-of-the-line bikes than Herse or Singer, so maybe the few failures just haven't been recorded.) Maybe it is just that some twin-plate designs fare better than others...
A lot of the best tandems in the 1930s also used twin-plate crowns
(see "Image Archive" on the VBQ web site) and cantilever or Jeay
"roller-cam" brakes with brazed-on pivots. I don't know how well
these lasted.
--
Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
http://www.mindspring.com/