upon further inspection of my Peugeot mixte, the simplex front derailleur is split at the usual place, what would be an economical solution? for replacement.

Pretty much anything will work.

I'm replaced the Simplex front derailleur on my UO-8 with a Suntour Compe-V and it's been working flawlessly. Among many others that should work, the Suntour Spirt is another cheap and plentiful option.

If you want to try keeping things original, I still have that front derailleur from my UO-8. It's intact and I'd be happy to give it to you.

These derailleurs crack me up:-(

Yep, pretty much anything. I've gone Suntour to replace mine

Suntour all the way...and...does not need to be one of the "best" Suntours either...

Huret! Keep it French!

I've been running a Simplex front derailleur repaired with tubular tire rim cement for 8 months. Seems to be a permanent repair.

Never ever give up on a Delrin Simplex derailleur.

I would be looking for an adhesive that bonds acetyl type plastics, usually a two part system.

I have one that has typically cracked, I was going to bond it then bore two holes and run a long 00-90 brass machine screws into it (decent hobby store item), if I recall there is room to the inside of the M5 fastener.

I have a mid 70's AO-8 and found a Simplex FD on Ebay for $10 from a guy in France.Another $10 for shipping and it is good as new. Of course it will eventually crack like the others.

I'm starting to re-think my practice of running these derailers into the ground, as the unwanted failure could occur at any time, which could actually be dangerous or at least damaging to other parts of the bike, depending on circumstances. Think about it...

If a crack is repaired, how strong is the repair? Wouldn't it be cool if there was some way to run a threaded metal repair though the cracked area?

One thing about replacements is that sometimes the clamp diameter is actually 28.6mm instead of 28.0mm, so make sure the clamp closes with some discernable gap present where the clamp pinches shut. A little filing will fix this if needed, as will a thin shim of (preferably) metal. A plastic Simplex replacement could also be 28.6mm, which should not be clamped on a 28mm seat tube without shimming first (to prevent unwanted flexing stress).

I would think that a Campagnolo Velox derailer would make a suitable replacement, but the Simplex and Campagnolo cages may not be interchangeable because the Campag derailer's push-rod is tilted on some or all of those.

I scored a pair of 1961 Simplex "Export 61" derailers, which are near-copies of the plastic ones, for possible use on my Steyr Clubman when the time comes (any day now, cracks showing!).

I've had much better luck with the plastic rear derailers myself, but have seen the limit screw bosses crack and even break off. I'm currently still using cable tension to control the hi-limit travel since the boss broke off during a tip-over 20 months ago.

It may look as good as new, but I have no idea if it is even half as good/strong as new. I have a NOS one that I also don't really know about for actual use, so likely will save it for a real collectible bike or sell it in box.

I've seen LOTS of Simplex front derailers crack over the last 10 years, seems that the Delrin has age limits, at least once they are installed.

We need a fly on the wall who was there when Juy and Co. perhaps first discussed how long that this material had to survive in service!
Surely they would laugh at those of us still using these old derailers!

I have a pair of (as yet) uncracked Simplex derailleurs and intend to remove and store them. As others have said, Suntour would be a good substitute. However on this bike current plans are to change to a wide-range touring set-up with parts already in hand: A Campagnolo Daytona triple chainset, Daytona triple front mech, Capagnolo Record 8 speed barcons, Shimano 105 long-cage rear derailleur, Shimano 14-28 7 speed freewheel, KMC gold 9 speed chain. I believe these will all play nicely together, will report back when it's done. Anyone see any problems likely with this mix?

I'm using some old very thick Panaracer stuff. Has worked well for over two years now, securing some loose floor tile in my bathroom.

Simplex made very nice, all metal front derailleurs as well. Why not consider one of those?

SJA-102

I currently have a Nuovo era Record derailleur on my previously Delrin equipped bike. Looks and works nice.

Yes they did and you can easily find them with the housing stop required to make them a direct replacement.

Yes they did and you can easily find them with the housing stop required to make them a direct replacement. The SJA 102 shown has it. I'm using a couple of them.

My delrin derailleur

Difficult to see the crack with black plastic on a black frame.

Immediately visible when removed. Just a few mm, or a little turn of the screw, away from failure.
My replacement a Super LJ, a little pricey, but the pretty girls always are.

Bad enough when they crack. Even worse when the derailleur feeds itself into the crank rings. No real ring damage, on this example, but the potential is there...

I'm wondering too if Delrin does not really like oil, like some other plastics don't??

Hmmm... maybe there's a way to run a threaded reinforcement (or two) through there before it cracks? I've got a couple of these things, still intact, in my parts bin. Perhaps it's time to drag one out and do a little exploratory drilling.

All you need is some copper wire or, as others have mentioned, glue and voila, an invisible repair..:-(

David,

Peugeot was behind the whole thing!

In 1961 Lucien Juy introduced the Simplex Juy Export 61 rear derailleur which was superior in design to most others on the market for the next 10+ years

Simplex Juy Export 61 derailleur

Shortly afterwards Simplex started making variants of the design using DuPont Delrin plastic parts in cooperation with Peugeot.

The "match box" style front derailleur whether Simplex or Campy was another poor design that never worked very well!

I had a parallelogram Huret front derailleur on my 1964 Bridgestone randonneur bike and it worked without any problems.

The Jubilee front derailleurs with the aluminum clamps are delicate and fragile but the all steel Huret front derailleurs are sturdy, reliable and easy to shift. You can find them dirt cheap on eBay.

Original Alvit



Later Challenger model




Addendum: Several people have mentioned using an all metal Simplex front derailleur. Besides the "silk stocking on a rooster" notion, the OP may run into problems because the old Simplex FDs required a piece of cable housing between the BB cable stop and the derailleur arm.

The newer all metal Simplex FDs came both ways - with a front cable housing mount in the clamp hinge or an arm on the rear for use without the housing but with a wrap around or under the BB cable guide.

For use with cable housing





The early Hurets used the same method of running the shift cable through a housing... That's why I recommended a Huret.


BTW, Daniel Rebour warned Lucien Juy and the rest of the French bicycle industry that they were forever condemning themselves to the image of producing cheap, fussy products. His warnings fell on deaf ears!



Remember, these were the folks who created the Maginot line before WW2!

verktyg

Chas.