It was something called a "retro-direct" system and many Hirondelle bikes used it from 1924 to just before WWII. A couple other French manufacturers produced similar derailleur and chain systems including one named "Le Crack" (yes, really). They are mentioned only very briefly in "The Dancing Chain", but I can't figure out how they work. In the book it shows a double pulley device mounted just behind a crankset which had TWO chainrings - though I see only one on the PBP bike. So, I guess you'd have two speeds in the back and two more up front... that is, unless the chain routing somehow multiplied the possible number of different gears you might achieve?
I'd sure love to see that Rube Goldberg chain routing in action!
Bob Hanson, Albuquerque, NM, USA
usazorro@yahoo.com writes: Wow! Now could someone explain what's happening with that chain? I've never seen that routing employed before.
Curiously,
John Barry
Mechanicsburg, PA, USA
> Joel Metz took this photo.
>
(http://www.blackbirdsf.org/randonneuring/2007_pbp/2007_pbp_13.jpg )
>
> Here is a great example of an UN-restored bike still
> being put to demanding
> use. In this case, a 1920s Hirondelle. You have to
> admire the spirit of the
> British cyclist who entered the PBP with this one.
>
> Bob Hanson, Albuquerque, New Mexico, USA
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