I'm cleaning up and old Gitane Grand Sport beater to make it a clean beater
Repainted it in the same color, ordered stickers (more expensive than the whole bike was worth when i got it!), cleaned up rust electrolytically, replacing some parts on budget, gonna put on it a Brooks B67 honey color saddle and white perforated Deda bar tape for now

So i need to replace a Simplex rear derailleur for an all metallic one, no black plastic, and not requiring any modification/fabrication work.
Which derailleur should i get? Are there any moderns ones that fit?

If there is no hanger I would look for a nice early '80s Suntour with a claw.

I can understand the desire to change out the Simplex - I had a chain jam in one the other day and the whole thing kind of "exploded".

I just went to my parts bin and chose the cleanest Shimano SIS off of some big box bike I stripped and had it adjusted and running in about half an hour - though interestingly the Shimano seems to need more cable travel to reach all the gears than the Simplex did. I am still using the Simplex friction shifters. Shift much better.

I should think, that for a quick and dirty period correct all metal look, an old Shimano Tourney would look good, and I would expect an improvement in action over any of the later plastic Simplex units, eh? I seem I see those Shimano Tourneys on about half of the lower end bikes from "the correct" period - the other half have ... something else. I have a couple in my life now that came on bikes I got for 10 bucks at the ReStore.

Then - you have a good looking rider while you shop for a period correct upgrade unit - or modern unit that looks right ... if you must ....

looks like the chain is routed wrong around your pulley wheels.



if there's nothing wrong with the rd, i would try to use it. complely overhaul it first.

if you do overhaul it and haven't done so before with a simplex rd, take detailed notes all along the way and take photos so you can reassemble it easily. it can be tricky.

but if set on changing it, and you're not set on keeping it french or matching the fd, suntour is a good choice.

I've had good luck with the cheap Shimano SIS adapters ($3 or so) and any ol' Shimano rear derailleur:



Shifts so much nicer than the Sachs piece of **** that was on it before.

Thats a nice classic french bike. Huret Svelto would be my first choice. Although the Simplex you have if set up properly would be the way to go. I think I'm the only one on the forum that likes the Simplex Prestige. I have never had a problem with the many examples I have owned. They shift darn nice.

I used one for many years back in the late 60's. My wifes Gran Prix has them. A little spongy, but they work. Suntour V Lux works well too. Keep them out of the sun. Delrin will "dry" up over time.

That is because of the slant parallelogram design shipmano started using as soon as Suntour's paten expired.

It is setup that way to reduce pulley friction.

Thanks everyone for replies!
Quick question, can you ID the exact year/model of my bike? I thought it's early 1970's but that Simplex rear derailleur that came with it looks too "modern" for the early 1970s - black plastic...?
Bike full pic https://i.imgur.com/muahGSg.jpg

Simplex started monkeying around with "plastic", actually Delrin, a relative of Nylon, in the mid to late 60's, I believe. Plenty of French bike boom bikes came with those plastic derailleurs. Though some models were slightly better than others. I had the Criterium model on my Gitane, and it is a fairly serviceable design.

This would sure look nice on that bike. A definite upgrade.

Simplex Super L J Prestige Made in France Road Bicycle Bike Rear Derailleur | eBay

Would it need some modifications? Or can a bike noob with a pair of hand tools unscrew the old one and put on this one without any adjustments?
Is the price not too expensive? Could i find an identical or similar one for less?...

No mods required -- just unbolt your Simplex with its claw and bolt in the claw-mounted substitute of your choice. The Huret Svelto suggested by big chainring would be a superb choice and country-correct, but any of the suggested Japanese derailleurs would work well, and there is ample precedence for European bikes with factory-installed Japanese derailleurs, most of which will require a somewhat longer cable housing.

If the end of your shift cable is frayed, or if there are any broken strands anywhere along its length (particularly at the shift lever), just do what the pros do and replace the cable instead of trying to salvage it.

i've never heard of this before. i thought there was only one way to route a chain around rd pulley wheels to ensure proper operation.

edit: i can't tell by the photo if it's routed wrong or if the pulley cage is mounted wrong. either way, if the rd works, why not just fix it. it also looks like the derailleur is sitting too far back.

The last year for those foil decals was 1973. That's as far as I can narrow it down for you. It's hard to date Gitanes. I've never been able to narrow my Tour de France down more than to early seventies.

There's nothing modern about that Simplex Prestige! Big chanring is right, they shift well if they're in good condition. The pulleys often fail, but they're easy to replace.

I would keep it all French if it were mine, but it's not.

I've been reading through the 'Danching Chain' chain again. back in the early days racers eschewed pulleys because it was believed they caused drag. Several single pulley designs, including one two pulley that on swung up out of the chain route, after it was all but proved that two worked better at shifting and drag was a non issue.