Campagnolo Chorus 10s rear mech—not enough range for frame?

a weird one

i'm trying to get a Campag Chorus rear mech (10-speed, 2nd gen, I think about 2007/8) to work with a Look 595 frame, also from around 2008 i think.

basically, the mech's higher limit screw, when cranked all the way in, places the jockey wheels just outboard of the smallest cog to the extend that the chain drops off when i turn the cranks. when i (manually) push the mech across the cassette to shift through the gears, it stops on the second-largest cog just kind of by itself, the lower limit screw isn't even touching.

technical docs for this generation of Campag are rare, but the more modern stuff says that it will only work if the distance between the outside of the dropout and the outer edge of the cassette is under 12.2mm. on my bike it's more like 15mm, so this all adds up.

i just find it almost impossible to believe that campag rear mechs are simply not compatible on frames with thick dropouts. i can't move the cassette outwards with a spacer because there's not really room.

googling gives me nothing, so i must be missing something obvious. anyone had anything remotely similar? longer limit screws might help, but if the mech's overall range won't cover the cassette then i'll have one cog out of action...

"...when i (manually) push the mech across the cassette to shift through the gears, it stops on the second-largest cog just kind of by itself, the lower limit screw isn't even touching..."

That really does sound like the mech just won't work with this frame.
Bonkers.

How much space have you got between the outside of the smallest sprocket and the inside of the drop out? Not much I presume.
What hub are you using?

Does this have a removeable/replaceable drop out and mech hanger?

If so is it original?

If it is removable can you source another one and experiment with filing/machining the hanger thinner?

good questions. I will respond in a bit with some.pics

General shot from the arse end of proceedings. Very little wiggle room to the right of the cassette. Even less so when chain is in the big ring

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Mech/frame interface. The mech will be blocked by the frame if it has to move inwards...

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I suspect that isn't the original hanger.
Looks like this one has been filed to fit for some reason.
I've just looked at replacement hangers and they don't look very different though so don't think a new one would solve this.

As a bit of a bodge you could get a hanger extender (for using on large range cassettes) and install it on the inside of the current hanger to bring the mech in towards the cassette.

It will look a little odd and may require some filing and a longer bolt, but will get you rolling.
https://www.sjscycles.co.uk/gear-spares/aluminum-rear-derailleur-hanger-extender/

thanks for the pragmatic solution. As it's meant to be my 'nice' bike, i'd rather not compormise like that. this affair might be the catalyst i need to (further) massively consolidate the parts and frames i have. i actually have SRAM stuff that can go on this bike. fuck me tho – how can this groupset and this frame not be compatible?!

lol from the sale thread when i bought the frame:

However, there are a few minor issues that came to light after I had purchased it. The rear derailleur hanger part of the frame, I believe it has been repaired at some point in its life, as it looks non standard. I asked the previous owner if it had ever been crashed and he said no, so perhaps it's a non standard 595 drop out. Anyway, it works perfectly. It's a little thick so if you are thinking of running it 11 speed then I'm not sure you would be able to access the biggest cog. I was running it with sram force 10 speed just fine.

Yeah the inner face of the mech hanger is usually flush with the inner face of the dropout
Whilst obviously not completely necessary as the contact face for the derailleur is the outside face rather than inside like the dropout, yours does seem quite a lot outboard from the cassette.
Looks as though a similar but incorrect mech hanger has been bodged to fit

Actually it does look to be the right one after a quick google. Suspect it’s just scuffed. But weird that the mech is so far out compared to the cassette

yeah, i think regardless of the hanger shape and size, the mech cannot move further inboard as part of it is in contact with the outer face of the frame itself.

i reckon it's been repaired. it's not the same style as the NDS rear dropout at all.

Sorry the light is awful

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Thor Hushovd's 595

I did a quick French Google and it seems that broken dropouts aren't that uncommon on this model. Not a great design if the hanger doesn't do its job during a fall.

Good luck sorting it out, Chorus 10s has aged well.

Chorus 10s has aged well.

are you in a buying mood maybe :D

Looks pretty similar to this - it is a crazy thick hanger/dropout

Looking at the image of the hanger on your bike, in your image, the material of the hanger doesn't look as if it is actually thick enough, at the point where it is bolted to the inside of the hanger, it's maybe half the thickness it should be.

It's as if this hanger was made for a dropout of similar shape when seen from the "side" but with a shallower recess for the hanger to bolt into. As others have said, maybe a near match, maybe cut to suit, maybe for a later version (or an earlier one) of the same dropout.

The best plan is to contact ZyroFisher, as the current importer of Look - and see if they can source a hanger for you.

BETD or some other third party might also list the correct item.

If you really don't (for whatever reason) want to go down that avenue, you could make a flat plate the right size and with drillings in the right places and asndwich that between the hanger and the inside surface of the dropout to bulk out the inner surface. You'd need longer screws of course. There are risks to this approach- the threaded part that the screws are engaged into will be a long way from the heads of the screws - so they will be a big potential turning moment on them, especially when you are cross-chained. You'd need (at a minimum) to keep a close eye on the tightness of the hanger bolts over time ...

Having said all of that, I know I've built and worked on 595s in the dim and distant past with CA10 and 11 (same spec for smallest sprocket position) and not had a problem that I can recall, so I am pretty sure this is the wrong hanger. It just "looks" wrong (no pun intended), apart from anything else.

the hanger is neither here nor there, I think. the problem is that the rebuilt dropout puts the entire hanger too far outboard. And even if the hanger could be shifted inboard with washers or filing thinner, the mech would still butt up to the outer face of the dropout

Can’t tell for sure from the pictures, but is the derailleur screwed in all the way? The 1st pic looks like it’s not.

Edit: looks like the derailleur isn’t screwed in fully but it’s already touching the drop out. Is that what you meant by it will be blocked by the frame if it has to move inwards?

No. The mech has a circlip which I think retains the main screw. I guess this is what makes it appear as if it's not all the way in. It is (was) definitely screwed in properly.

What I mean by the frame blocking it is that the surface of the mech that interfaces with the bike is larger than the hanger itself. If I were to somehow move the hanger inboard, the mech could not follow it because the mech would hit the frame.

You can see on my first pic that the large silver disc on the mech would hit the hanger bolts.