Just finished putting together a Peugeot with the plastic Simplex derailleurs. Getting the rear to work was the worst multispeed experience since my Varsity in the '70s. The bike is a 12 speed, getting all 6 sprockets to work reliably took a lot of tweaking. No B screw? One of the few times I really needed it. I suspect the stem shift levers don't have quite enough throw for the job as well.

I won't even go into the front derailleur sinking and twisting at every attempted shift. It's a clamp-on that is about 1/2 a millimeter too big. Waxed the frame while the bike was apart making it too slippery to hold. A beer can shim and a dab of silicone did the trick.

Depends on which derailleur. While the SuperLJ is often regarded as even better than the Campagnolo Super Record, this of course isn't true for the cheapest bottom-of-the-line derailleurs they sold - some of them are indeed quite bad.

But apart from that, as problematic as the Delrin plastic may be (especially when it ages), back then it was a great invention in lightweight building. E.g. the Simplex Criterium is a quite nice derailleur. Basically, the Delrin plastic idea is the same as with carbon bicycles nowadays. Biggest problem was, derailleurs with plastic parts didn't look that good, and a lot of people disliked them. Yet, the quality was quite good, and I wonder how many carbon bicycles from today will still be around in 40 years...

Which one are you using - Prestige?



This one is on my gas pipe Peugeot and after switching in the jockey wheels from another Prestige derailleur it set up really nice and shifts very well. The only thing I really don't like is the lack of a barrel adjuster to work with cable tension. The plastic eventually cracks but this one is in excellent shape and I'm enjoying it while I can.

Fine working derailleurs, I think. The fragility of the plastic seems to be their weak point. It does seem your adjustment issues stem (pun intended) from the choice of shifter and a ill fitting clamp.

Penance? Go place a vigil candle before your Simplex components.......lest a worse fate befalls your Peugeot

Like I mentioned in a recent thread, Simplex just did not use plastic properly, as in not in the right areas of the derailleurs. Why they used it on high stress areas is puzzling as it not only negatively affects the reliability/life of the derailleur, but the resulting flex also affected their performance on the bike....
I just cringed when you mentioned that you had problems making that front derailleur stay put on the seat tube. as I suspect that it's one of those with a clamp that is half plastic which most people had cracking apart on them after they also tightened it as much as they can on their bikes just to make it stay put on the seat tube....
Do yourself a favor and get the later Simplex SX 610 and the all metal front derailleur that was usually matched up to it. There's sitll a couple of Delrin parts on the SX610, but Simplex figured out how to use the material properly on the derailleur by that time.

Chombi

Additive to everything above, I think a lot of the flex is in the plastic levers, provided the derailleurs are in good shape and properly set up. Replacing the levers alone will likely improve the entire system.

I had Simplex on my old Grand Prix... When it worked, it worked fine. After about 10 years of use on a 30-40 year old plastic part things started wearing out and cracking. I suppose that's a fairly good amount of time for existence, but I have older bits made of steel and alloy and they're still working as reliably as the day they where made... I won't touch the Simplex stuff anymore.

sja 102

Definitely

I think the bigger problem with the Prestige was the flexy plastic levers they came with. I cleaned up the SImplex on my UO-8/9/10 really thoroughly, gave it new biscuits and a set of metal levers, and it works quite well. I don't know how long it will continue to do so, but it really is very nice now.

Simplex derailleurs have a sprung upper pivot, so the B-screw is superfluous.

Are these the plastic shifters? If so, they're not worth struggling with. Replace them with something more solid.

Perhaps a English-diameter (28.6mm) clamp on a French diameter (28.0mm) seat tube?

Some versions of the Simplex shift levers incorporated a barrel adjuster at the shift lever instead of the derailleur, but this requires full housing on the cable:

1. Still a pain to set up. I'm a boring Shimano type guy.

2. These are metal shifters. They go through the full throw to shift the rear sprockets. Cable pull just seems a little short.

3. Might be. The bike came with two left hand brake levers, so the mistake isn't inconceivable. Seem that's the amount by which it's too big.

This bike was bought from a guy who bought it at an estate sale 20 years ago. Original buyer got it for his wife to lose weight. Bike didn't get ridden. 2nd owner bought it for the same reason. Wife suggested he ride it. Bike hung for 20 years in the garage. I'm not mentioning that my wife rides it. The curse ends here. I boogied around the block on it. Other than the absurd BMX/apehanger aftermarket bars, this thing is a plush cruiser. Hard to keep up my rugged masculine image on a silver French Mixte.

rubbing some tri-flow into Delrin, I have found, keeps them from going brittle. So long as they aren't cracked to begin with.

Also, I have a cat named Delrin

My SLJ 6000 isn't bad at all.



It handles the 14-28 7 speed freewheel even though it's only rated for 24 teeth. It even has a barrel adjuster, not that it's a big deal for a friction derailer.

The levers that came with the Criterium on my TdF are actually quite nice. All metal with plastic caps. Work fine.