I'm here in Tuscaloosa, AL, just haven't had a lot of time for email of late. One of the many reasons Simplex is my favorite RD is that Simplex is "universal" in that it fits Simplex, Campy or Huret ends. Most classic Simplex RD's had a nut inside the DO that that threaded onto the upper pivot bolt. The OD of the nut fit nicely in a Campy or Huret threaded DO, although it did not use or need the DO threads.
Some later Simplex RD's used a male-threaded bolt inside the DO that engaged female thread in the upper pivot. But the bolt had a sholder that fit inside the DO, so this version still fit all common DO's. One reason for the versaltility of Simpex RD's was that they used a spring-loaded upper pivot which meant they did not need a hard stop to limit the rotation of the RD. That's why Simplex DO's did not have the notch seen on Campy and Huret DO's. Since a Simplex RD does not use the stop notches, it is indifferent to the different placement of these on Huret vs Campy DO's and happily ignores this issue.
Other advantanges of the sprung upper pivot are greater range and smoother shifting than a Campy or Huret RD of the same cage length. It's no coincidence that virtually all modern RD's incorporate the Simplex sprung upper pivot. They also incorporate the SunTour slant parallelogram, but that's another story.
In The Day, it was common for at least US riders to file a notch in the Simpex DO on their PX-10 or similar French bike to provide a stop for Campy NR. Truth was, this was totally unnecessary, as even the plastic Simplex Criterium shifted better than the Campy NR, and the alloy SLJ, which was introduced in the early 70's, was IMHO as elegant as the Campy NR and nearly as durable.
Tuscaloosa, Alabama, USA
From: Ben Kamenjas <firstname.lastname@example.org> Subject: [CR] Simplex rear derailleurs on Campy dropouts? To: email@example.com Date: Thursday, July 8, 2010, 1:35 AM
Being that all the talk is sounding like the yearly Masi-fest, in honour of Jerry Moos (where are ya Jerry?) I thought to bring discussion back to French (yes, I know he owns a Masi) and to be more specific: Simplex !!!
I don't have a Simplex derailleur at hand but I have an itch for French and am wondering if there's any issues to fitting SIMPLEX rear derailleurs to Campagnolo 1010 type dropouts with threaded hangers? I don't wish to use a hanger or "claw" and I'm thinking of mid 70's and early 80's Simplex derailleurs like the SLJ or 610. It might be a non-issue ... I just don't know.
To keep our resident Leporid from beating on his well worn keyboard I did search the archives and IntraWebs but didn't find anything specefic to answer my basic question.