Yes, it will fit just fine. Not counting the hanger plates for DO's without a hanger, their were, AFAIK, two types of attachment for Simplex RD's. Most or all of the RD's in the 60's and early 70/s had a male threaded pivot bolt which engaged a nut/collar inserted into the backside of the DO hanger. Later, some like the one in your photo had a male threaded collar, and the pivot bolt was female thread. In neither case did the pivot bolt or collar engage any threads in the DO, which is why classic Simpex DO's did not have or need threads. But the Campy pivot bolt, rather conveniently, had a thread diameter just enough larger that a Simplex collar would slide smoothly into a Campy DO, neither too snug nor excessively loose. So the Simplex did not use the DO thread, but was not hampered by it. The Simplex RD also did not need the notch in Campy DO's used as a rotation stop by a Campy RD. But again, the notch did not hamper operation of the Simplex.
So while a Simplex RD can be used on a Campy DO with no adaptation needed, a Campy RD could only be used on a classic unthreaded Simplex DO if one tapped Campy thread into the DO and notched it to provide the rotation stop. Quite a few Peugeot PX-10's did get modified in this way to allow use of a Campy NR, which was prettier, probably more durable, and to a lot of people "cooler" than the original Simplex Criterium, even though the Criterium actually shifted better.
I think it was sometime in the mid to late 70's that Simplex DO's began to appear notched and threaded for Campy RD's. This made the Simplex DO's more "universal", as they would now take either Campy or Simplex RD's and most others. But as someone pointed out earlier, this may have cost Simplex sales of RD's in the replacement marked, as it was now easy for someone to replace a Simplex RD with Campy or Suntour or Shimano on a French bike.
I've no idea why Simplex changed from a female threaded nut/collar inside the DO to a male threaded bolt/collar, as it really does not seem to matter in terms of mounting or operation. And I'm not sure if they made this change on the whole line or only some models.
Regards,
Jerry Moos
Big Spring, Texas, USA
> From: mitch harris <mitch.harris531@gmail.com>
\r?\n> Subject: Re: [CR] Simplex CX630 Rear derailleur
\r?\n> To: john@os2.dhs.org
\r?\n> Cc: "CR List" <classicrendezvous@bikelist.org>
\r?\n> Date: Wednesday, May 13, 2009, 1:50 PM
\r?\n> On Wed, May 13, 2009 at 11:39 AM, John Thompson
\r?\n> <johndthompson@gmail.com> wrote:
\r?\n>
\r?\n> > ...Whoa, hang on! I just found an SX-630 (long cage)
\r?\n> in my Big Pile o'
\r?\n> > Derailleurs! Feast yer eyes on this:
\r?\n> >
\r?\n> > http://os2.dhs.org/
\r?\n> > http://os2.dhs.org/
\r?\n> >
\r?\n>
\r?\n> Can the fixing bolt shown in the second .jpg be made to fit
\r?\n> a standard
\r?\n> drop out? How were these supposed to work? The nut
\r?\n> threaded into the
\r?\n> drop out from the backside of the dropout into the fixing
\r?\n> bolt? Did
\r?\n> the fixing bolt also thread into the drop or was it just
\r?\n> this
\r?\n> rear-side nut that threaded into the drop?
\r?\n>
\r?\n> Thanks, I have a Simplex der with a fixing bolt like this
\r?\n> and want to
\r?\n> know what it will take to mount it to a regular Campagnlo
\r?\n> style drop.
\r?\n>
\r?\n> Mitch Harris
\r?\n> Little Rock Canyon, Utah, USA