The 122 BCD 37T inner ring I mentioned earlier also fits the Stronglight 49 chainset you posted. And the good news is that you can buy those new:

https://www.redclovercomponents.com/..._37_Teeth.html

A smart and practical solution to keep in mind, still unsure if want to do this to a nice Campy
Excellent, very useful !!!

Ok, enough reading and researching over the past days.
I had a “go” from my friend for a potential switch to a Simplex rd, provided it’s a nice one with no or minimal delrin. If I understand correctly the Simplex range, this basically narrows down to the SX410-610-810 and the SLJ models.
Among the SX, the 410 seems the most available (but not the GT version).
Concerning the SLJ, among the different posts, I read verktyg impressive tests on these models and how they might not clear on some >24t fw if cogs are too close (e.g. 7s fws). Also interesting were some comments on how it could possibly be hard to wrap chain if a large triple crankset is used, and on how it is not easy to recognize Simplex models (the latter point being reassuring as I was starting to doubt about my cognitive skills when going through the Simplex catalogues )
Given my project would require a triple crank and an up to 24-28t fw, it is important to identify the proper Simplex rd model and mounting before spending money to purchase it.

Here below some SX410 photos from ads on ebay, I’ll post some SLJ asap.

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And here a couple of SLJ found on local ads. The second one has black bolts, maybe a later and higher capacity derailleur? It also has a hanger, not sure if it can be direct mounted to the frame with its bolt.

Any suggestions welcome on these Simplex solutions as to whether they might work with the targeted setup. Thanks !!!

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I've used the 4/6/810 RD on a triple crank (52/42/28) with a 13-25 7 block successfully. Granted, the 28 was a bail-out used only with the 25t rear cog.
If you go with a Simplex RD, remember that they mount in a very different manner.











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Excellent, thanks top506 , this is the kind of combinations I’m targeting, so good to know. Although the Simplex mount in a “very different manner” seems scaring… More seriously, is there any particularly setup detail to be aware of? I was looking for a direct mount derailleur to simply bolt on the Simplex dropout hole, am I missing something?

The actual attachment is from the rear of the RD. The Allen socket on the front is only to adjust spring tension. There's a pretty good blow by blow procedure here on the forums somewhere.

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I'm running the Simplex SX 410 RD on my 1982 Peugeot PXN 10. It came stock on the bike. It can handle an impressive amount of chain for a short cage RD. In fact, that's true with a number of simplex RDs. Plus they have upper and lower pivots and shift better than a campy.

Here's a good description:

https://mariposabicycles.ca/2016/01/...ng-derailleur/

I'm running 50/36 rings and a 14-28 freewheel on the PXN 10; the SX 410 handles that nicely.

Velobase has it handling a max cog of 30 with 30 teeth of chain wrap. I have used that RD with a 30 tooth in the back. It worked fine.

VeloBase.com - Component: Simplex SX410 T

Personally I wouldn't run a triple. I'd go with a stronglight 86 bcd crank (or the TA if you prefer) and run it with smaller rings (say for example a 48/32). If you get a 13-28 6 speed suntour ultra freewheel, you'll end up with pretty decent gear ratios. Think about cutting out the top and the bottom a bit and focus on the middle gears. There are always trade offs in building an old bike. I reckon that's part of their charm.

I have a 70s Mercier 300 I need to build up and that's more or less what I'm going to do. I want to be able to climb some hills on that bike.

On my 1971 Jeunet, I went with a Campy Victory crank that offered 116 bcd. That way, I could use a 47-36T combination. On the rear, I have 14-24 with a NR. This yields 89 gear inches on the top end and 40 gear inches on the low end. This range fits the purpose of this bike and matches my abilities perfectly. True, I spin out at 32 mph or so. Who cares?

Also, I'll confess that the Victory crankset isn't period correct at all, but it doesn't look harshly out of place either. So...

a key point to note, when using a “short” cage rear derailleur, note the comment about “bailout” - to get error proof and no damage shifting with a wide range triple and pretty wide range rear freewheel, a long cage rear derailleur is what is needed

Ok, I see
Thanks for the tips, the SX410 seems the one providing the most flexibility and solutions. A double crank would be ok if, as in your case, you have a small enough inner chainring and a large FW, I didn't think old front derailleurs could handle a double 50-36, interesting. By "cutting" do you mean avoid extreme crossing like big-big or small-small when installing a triple?

Interesting, thanks for sharing, admittedly my friend needs slightly higher gear ratios...
Yes definitely right, unfortunately I couldn't manage to find long cage Simplex RDs yet, but it seems the SX410 could be a nice compromise, doesn't it?

Anyway, the picture is getting clearer thanks to all of you. The only remaining doubts concern SLJ derailleurs which would be the nicest Simplex solution: I admit still struggling to understand if and which one might be suitable for this project given verktyg comments and tests in a specific thread on these derailleurs. Any suggestion is more than welcome...

I'm suggesting cutting out the high and the low gears. There are always trade offs with gearing on old bikes. A compact double with a decent size freewheels gets you a lot of very usable gears. The stronglight 99 has an 86 bcd crank. It can go as low as 28. The TA cyclotourist can go as low as 26.

Triples will give you more gears but you may not be happy with the shifting performance running old school derailleurs.

There is a 5 pin GS crank, rare but out there. Has the Record look.
When I was racing it was 47x15 (44x14 was allowed too) to stay with the cat 1's it was hummingbird legs.

After a few months the Mercier restoration is finally over.
I finally opted for a triple Stronglight 99 crank (found one with a drilled small chainring) to work with a Simplex SX410 rd, shifting is fine and they can handle a wide gear range. A new bottom bracket was necessary, luckily the chosen spindle length was fine and the chainline came up quite right. The Campagnolo fd can handle the triple, although it uses all the possible extension on the outside to reach the big chainring. I left the original brake shoes, but braking is not optimal. I will probably need to make an exception to the vintage rule and use modern ones. Indeed, the bike is all period correct from the end of the ‘60s, excepting the wheels which are a few years younger. Final weight at around 24.5lbs is fine, not the lightest but still light for a 58-size Reynolds 3-tubes.
Here’s a picture of the “bijou”, hope you like it, and thanks again for all the advices.

The bike looks great! I am glad you went with the Simplex rather than modify the hanger, and kept it mostly French.

Love the hard ano rims too, not everyone does, but they’re my favorite.

thanks, yes, French components on a French bike was the best solution! We had long discussions around black anodized rims and eventually decided they would have been nice with the bike colors, glad you like them.