I know lots of people drew Simplex hangers to fit Campy RDs, but what about the other way around? How direct of a bolt-up is it for a Simplex RD going onto a Campy hanger? Will the derailleur stop rest in the proper position? I know the bolt is narrower than a Campy bolt and fastens with a nut, will this cause wobble?

I have a nice set of SLJ mechs that I've had for a couple of years... I'm itching to get on a bike, but no more Frenchie frames in my stable for the foreseeable future.

I haven't tried it, but I don't see why not. The only possible problem I foresee is that the mounting bolt might be too short. Simplex hangers are much thinner in that area. There's only one way to find out for sure.....

Really interesting question. You may be the first one I've ever heard post this query. Interested to hear the answers. I've gone the other way, with my custom turned bolt. Wondering if a custom bolt would work here too. Not suggesting I can make one though. It would require a lathe that cuts metric threads.

Yes, I've seen your custom bolt for going the other way around... genius! Alas, I've got the reciprocal problem. I agree with GB, I think the flanged Simplex bolt might not be long enough. It will probably thread just fine into the RD from behind the hanger, but will sandwich the hanger too tightly and disallow free rotation of the RD.

I was thinking about using my SLJ5500 set on my soon to arrive Jack Taylor frame, they sure are purdy, but I think it might be time to just ditch all my French parts pr0n to help fund a more conventional set of comps. You saw my other thread, right?

I don't think so.

I didn't see your other thread SouthpawB. I like a challenge like this. But I'm hard-pressed to envision how this would work.
What is the diameter and threading on the end of the Simplex bolt? And how far does it protrude past the locator plate on the
rear of the upper pivot?

Never seen a Simplex derailer?

A picture would be worth a lot more than my attempt to explain here with words, but the Simplex hanger attachment system differs from Campy in that there is a threaded bolt (not sure of the threading, but it's significantly smaller than M10) that threads into the upper pivot of the RD from behind. The bolt has a non-threaded step-up (for lack of the proper term?) between the head and the threads which is wider than the threads (but still slightly narrower than 10mm), and when installed, this segment of the bolt is situated inside the non-threaded bore of the hanger, like a bushing. The step-up seats the bolt fully against the pivot body when tightened and is just slightly longer than the hanger is thick, such that the bolt can't compress the hanger between the bolt head and the locator plate, so the pivot can rotate freely. It's basically the reverse of a Campy arrangement. And yes, a bolt with a longer step-up segment would have to be machined to fit properly in a Campy hanger, otherwise the RD wouldn't be able to pivot freely with the bolt tightened. Making a bolt that would work universally would also assume that all campy hangers have the same thickness, which I don't think they do? Because differences in Campy hanger thickness are inconsequential to mounting a Campy unit to a Campy hanger.

You'll totally get it with one photo. I'll try to take a picture tonight.

EDIT: On second thought, it might be easier to just machine a bushing (or find an appropriately sized one) that's just slightly longer than the thickness of the hanger, and use a generic shallow button-head bolt in place of a proprietary bolt with step-up. I'm thinking something like a jockey wheel bushing would be a starting point...

Oh yeah, I can envision it Anton. But was just wondering about dimensions to see if it might be possible to machine a flanged "nut" that would sit in the Campy 10 mm hole, from the back, and thread on to the Simplex bolt. But there might not be enough room to do that. But if the Simplex bolt threaded section is much smaller than 10 x 1, it might work.

Hi Southpaw. I'm in the same boat as you. I have a NOS LJ 6600 in my parts box that I'm thinking about using on a non-French frame. I like the idea of machining some sort of bushing for the bolt. But, I was also wondering if you knew whether the derailleur tang on the LJs will have any issues when used on a Campy style dropout?

Thanks for any info.

If you're referring to the locator plate, I *think* it will work fine on a Campy hanger. The Simplex tang sits at about 1:00, in the nook where the hanger joins the dropout, so it should locate the derailleur roughly the same whether on a Campy or Simplex hanger.

Thanks, Southpaw. I was hoping this would be the case. I look forward to seeing if you give your project a go. Also congrats on the Jack Taylor.

I was thinking that a stack of narrow washers on the Simplex bolt can extend the step-up shoulder on the bolt?

I haven't actually done this, but you should be able to dial in any amount of top-pivot spring tension with a correct bolt setup in any case.

I think you might be right, but the step-up is not much wider in diameter than the threads, so the washers would have to have to be like very slim sleeves.

I finally got around to taking a picture:

This is absolutley correct.

Simplex derailleurs were designed to work with either type of hanger. The smooth shoulder on the mounting bolt is the same size as the threaded hole on standard dropouts, so they mount without any slop. It's a direct bolt-up - no extra washers required. Tighten the bolt all you want, it's not going to have any effect on the free movement of the derailleur.

Bertin used Simplex derailleurs extensively on their bikes in the 70's. Mine and every other Simplex-equipped Bertin I've ever seen has a standard threaded (Milremo) dropout.



SLJ 5500 T/SP derailleur. The cable housing was later shortened - promise.

I just went down to the garage and pulled the mounting bolt off a spare SLJ 5500 derailleur. Unless it's different than what you have, I can't see what all the fuss is about.

It's an M6 bolt and its overall length is 18mm, so plenty long enough to tighten up in a dropout of any width. The smooth shoulder section is 9mm in diameter & 3mm wide. The bolt fits very snuggly in a standard threaded 10mm hanger - I just tried it to make sure. (The 1mm difference is the threads on the bolt, i.e. a M10 bolt theads into a hole ~9mm in diameter.)

Is this the same as the mounting bolt you guys have? The 5000, 5500, and 6600's I've had are all from the late 70's - early 80's. Did earlier Simplex derailleurs use a different bolt maybe? I could post a photo if it would help.

That's what should have been done in the first place, like I hinted at in post #2.

SuperLJ, thanks for chiming in! I suppose that's what happens when one tries to over-analyze everything before experimenting-- you create hypothetical problems that don't exist in reality, and I am guilty as charged. I was actually thinking the shouldered bolt would be an issue since Grand Bois mentioned the Simplex hanger is thinner, but I should have just pulled a Campy RD off of one of my current bikes and tried it before posting here! And yes, GB, I should have taken the "only one way to find out..." approach.

I just looked closer at the photo you posted and that's exactly the same as the mounting bolt I have. Your derailleur will function perfectly on a standard 10mm threaded hanger with no modifications to the bolt or the hanger. I funny part is that I've been using these derailleurs for 30+ years and I've never even seen a Simplex dropout (with the derailleur removed that is) in person.

In my opinion, SLJ's are not only beautiful, they're also some of the nicest shifting of all vintage derailleurs - certainly better than anything Campy offered in the 70's. It's hard to tell from your photo of the back, but I think yours is a 5500 "T", which is the medium-cage model. It will handle up to a 30t cog with ease. A Jack Taylor with metal Simplex derailleurs sounds super yummy! You'll have to post pictures when you're done. Get busy...

Works fine here on a Roto dropout:

Just mount the sucker it will be fine worste case you need to add one washer. Yet I can't see why with a perfectly good campy type hanger one opt of Simplex if it wasn't already hanging on the bike.

Well, you're certainly not alone there, amigo. I'm renown for doing this.

Well, I happen to be getting a frame that doesn't have Campy mechs pre-hung, it needs period-correct mechs and I happen to have a period-correct Simplex set, hence this thread.

Aw...just send me that French crap, Southpaw and I'll provide you with some nice Italian stuff that will fit.

Ooh, what a pivotal decision that would be.