I was on the way to town this morning, and when I downshifted to 1st, I heard this terrible crunching noise and my rear wheel locked up. No fault of the derailleur, mind you, just my poor memory to replace that derailleur wheel bolt when I temporized a fix, or, to not shift into 1st before I did so.

Anyway, I'd like to stick with a better version of what would be period correct for this '75 Peugeot PX-50, does the derailleur on a PX-10 work well? Any recommendations? (Anything other that a plastic-bodied one, that is.)

I don't remember anything other than the standard plastic simplex on Peugeots of that era, from the cheapest to the most expensive. I'm impressed that plastic worked this long, the front derailleurs were dying contemporaneously because the plastic isn't strong enough

See:Simplex derailleurs

Finding a good quality bolt-on Simplex rear derailleur for a Peugeot is not going to be easy or economical.

Just go for a Campy NR instead........
Pretty much the same performance than any Simplex RD you can get from that era, but it will look so much better and also be more reliable because of the all metal construction.

It'll buff out.

So it seems the premature (40 year) failure of this rear derailleur was due to an extenuating circumstance. You have plenty of options now, virtually anything you can hang there with a claw, but I wouldn't hesitate to install another Prestige (this time with some stronger (Suntour) pulley wheels).

I think Simplex rear plastic derailleurs suffer by association with the Simplex front plastic derailleurs, which truly are the bane of man's existence on this planet.

And they shift better than Nuovo Record.

simplex rear derailleur | eBay

Simplex LJ and SLJ would be period correct but pricey. Suntour V-Luxe shifts well but would require notching the derailleur hanger for it to work. I cannot tell from your photo if you have a hanger or claw so that may not be an issue for you.

You proved my point.

+ 1. Those are crazy prices. I wouldn't overthink this. Get an old school suntour rear derailleur with a claw. It will work better than the simplex did.

I have a few simplex RDs I think I need to put on evilbay to finance my retirement!

Looks like a claw. Easy to find a Suntour or Shimano which will work. A Huret/Sachs-Huret could also be an option if you wanted to stay all Frenchy.

A super LJ would be expensive, but there is nothing special about an LJ. Lucien Juy's initials are on every Simplex derailer I've ever seen.

I'd look for an SX610 with a claw mount. Prices have gone up, but I have five and I didn't pay more than $20 for any of them. You have to be patient to get a good price.

Kind of funny the OP neglected the old plastic fantastic and finally killed it. Who would ever expect them to last this long? If anything it proves their worth. Bonus is when the jockey screw/nut went into the wheel, the plastic snaps saving the spokes and dropout.

I probably would scout a LBS and the junk bins for any old derailleur with a claw. Thinking a shop would feel bad for you and give it to you freely.

That would be the "quality" part of "Finding a good quality bolt-on Simplex rear derailleur for a Peugeot", right?

I've got my power buffer attached to my chainsaw at the moment.

You might need a little more speed and a little less torque.

Yeah, I looked at ebay only long enough to see 2 or 3 prices, geez, one guy wanted like $40 just for the jockey wheels. The only part that was salvageable on mine was the chrome front cage part for the jockey wheels. Anybody want it for $20, plus shipping? Actually, I saved the "Simplex" metal badge and glued it onto the Shimano derailleur that's now on it, just to mess with the know-it-alls.



Mine has a claw that has the hole to act as a hanger, for the record. I can attach whatever to it. Anything would be an improvement in the appearance department to the Shimano I stuck on it.

The little foil badge kept falling off my FD- I used shoo goo to re-seat it- but I sort of bent the foil. It looks like a pretty common problem- a lot of those SLJ FDs don't have the badges.

Your new "Simplex" looks allsome!

Uh-huh, (hiding face in shame). But, when you think about it, it lasted for 40 years, so can the plastic Simplex be all that bad? A good side of it was that had the derailleur been all-metal, it would have ripped out a bunch of spokes, instead of bending only 2 of them.

Well, after this, I'm absolutely not ever touching that Simplex front plastic derailleur, I'm telling you. The rear one was just fine for over 40 years, until I messed with it.

Yeah, exactly what I was saying above. KIND OF funny, huh? What kind? Irony? Sick humor?

I had an old Shimano that will work for the moment. Mind you, I fine-tuned the derailleur stops so that it won't go anywhere NEAR the spokes....

So that would in reality be a Shimplex. You might want to consider flipping the QR skewer end for end so that the closure is on the non-drive side.

Glad to hear you weren't hurt in that episode. When I saw your note about this RD event in your home-made rack thread I thought to myself that's why engineering something is a better idea than just making it and seeing what happens. But then I figured one would have thought Simplex might have engineered them better. At least that one last a long time, Prestige or not. Failure Mode Analysis doesn't seem to have been part of the deal back then. Where is ISO when you need them?

A Sunplex might shift better.

Yes, I wish a could find an almost all metal or nearly NOS plastic Simplex at a good price.