Assuming it has an RD mount incorporated into the DO, which would usually be the case with a 531 frame, the Simplex RD will have a threaded nut or collar which fits into the DO from the inside. The nut usually has a recess for an allen wrench as does the top pivot bolt on the RD. If the wheel has been removed, you can easily remove the nut/collar from the inside of the DO. Simplex RD's of this era did not engage the threads of the DO, so when the collar is removed, the top pivot bolt will simply slide out of the DO. In fact Simplex DO's were not even threaded. Huret and Campy DO's were threaded, but the thread diameter was a bit larger, to match the thread of a Campy upper pivot bolt. So a Simplex RD mounted on Campy or Huret DO's in the same manner as on a Simplex DO. The slightly smaller Simplex upper pivot bolt slid through the larger DO thread and engaged the collar inserted into the DO from the inside.. Note that on some models the piece inserted inside the DO was male threaded rather than female, so it was a bolt rather than a nut. The female thead on these would be on the backside of the RD upper pivot. This made no difference in the mounting/removal procedure.
Regards,
Jerry Moos Big Spring, TX
MICHAEL FLYNN <michael.flynn7@btopenworld.com> wrote:
Having found a complete pink late 1960's Mercier in a skip in France I have stripped it down for renovation. Can anyone advise me on how to remove a rear derailleur from a French frame of this age? I have read about the old French rear derailleur mount but it didn't explain how to remove the thing!
For those who like detail it's a 531 throughout frame with half chrome ends. The kit is Simplex, Mafac, Stronglight (great star shaped crank spider), Atom, 3ttt and Berelli. Not bad for a skip find!
There is a very similar one shown on one of the classic bike sites. The main differences seem to be the photos show an earlier chainset and no chrome.
Thanks.
Mike Flynn, Heathfield, E Sussex, England,