I found a nice 60's Olmo abandoned at work, built up with 80s touring parts. (I got in touch with a previous owner who said he sold it to an intern, who probably abandoned it when he left).

I've been rebuilding it. But getting the Duopar set up right after putting it back on is confusing me since it's not like other derailleurs I'm used to with the pivot at the hanger. Just tightening it down doesn't seem to work since it'll come loose in certain gear combinations.

So how do I bolt it onto the hanger correctly?

Photos? What kind of dropouts? Is there a tabbed washer on the attachment bolt? I have one, but have never mounted it. I believe that some were for Campy dropouts and some were for Huret....

It should naturally pull forward until the tab catches the stop on the hanger. It should be at approximately 45 degrees to the ground.

What exactly is coming loose? The cage is mounted on a second parallellogram (Duo-par, ya know!). And it moves freely, it's supposed to. The mounting bolt is the same as any other one.

This is where pictures become very helpful.

The one on the blue bike looks right.

The one on the red bike shifts better.

Wow, I forgot about this thread for a while. Here's my photo:


Pastorbob, do you tighten the bolt going into the derailleur hanger all the way tight? And does that part of the derailleur stay static, unlike how a standard modern derailleur pivots there?

I'll try locking mine forward as on the red bike.

For the record, I'm nearly positive Bob has a Duopar made for Campagnolo dropouts mounted to a Huret-stop hanger on Sporty. Given the design of the Duopar though, it's operating quite similar to a dropped parallelogram derailer; hence the better (though purely by luck) performance.

-Kurt

So... Does the main body pivot on the hangar or not? And is there anything I should be aware of when installing the chain, like tensioning for cage position or whatever?

Hmm, a little more experimentation and it seems to me the crux of the issue is that there's a lot of slack in the chain when I have a lot to wrap, and that the parallelogram pivot seems less springy than it ought to be. This derailleur is on a bike I found abandoned, so the elements may have caused that pivot to not be quite as springy?

Yes, you tighten it all the way to the dropout or hanger.

Kurt, I actually think it is the reverse, but I would need to check. Sporty's EcoDuopar is for a Huret claw, but I had a Campagnolo claw, which worked in my case.

It is supposed to be able to pivot around the upper pivot, don't lock it. The derailleur hangar bolt (upper pivot) needs to be tight, otherwise the whole derailleur can fall off. If that does not allow the derailleur to pivot, some kind of washer or spacer is missing in the pivot. There's no spring in that pivot. The vertical parallelogram does not have its own spring, it's "driven" by the cage spring. There needs to be tension on the chain.

What does yours look like with gravity working the correct way? You might have your chain too long or need to wind up the cage spring.

The attitude of the derailleur should be as Pastor Bob's is on his blue bike. If he doesn't have good shifting that way, I don't know what is wrong, but something is.

No, see if the cage can be wound up one turn, and if there's a rotation stop in there somewhere. I do not believe that spring has sagged.

I was going to post this exact same thread. My duopar def does not mount like all other mechs I've ever installed. I'll post pics of the small parts but basically it seemed like it should have more tension at the dropout pivot. Something wasn't right. This was on a simplex dropout that a prestige was mounted to prior.... Pics in a bit.

Also see if the spring is installed correctly.

This duopar is set up with the Campy hanger adapter tab resting on the pivot stop:

here's the dropout



and here's what I'm working with.






will this work? What's it supposed to look like? Is this setup meant for another kind of dropout? Why is the pivot bolt keyed and which position should it go in?

If the tabbed washer is against the stop on the derailleur hanger, I suspect you have a Huret-style tabbed washer on a Campy-style dropout.

There is no spring on the Duopar pivot. In use, the derailleur body is pulled to the fully forward position (as in Pastorbob's pictures) by chain tension. The derailleur body can pivot back to facilitate wheel changes.

Huret used a couple different mounting bolts as well. Most of the Eco models I've seen have a simple bolt with or without a locknut on the back of the bolt inboard of the hanger. Some of the titanium ones have a split mounting bolt with internal threads and a small allen head bolt installed from the inboard side of the dropout to lock it in place.

I think I've gotten this figured out-- I pulled the derailleur off, and the rotation spring was really tight until I ran it through its motion a bunch of times with my hand. But this is after I put on the Crane GT. Decisions, decisions.