Question for the Campy whisperers...

[sailorboy]

So I have SR12 on two steel frame bikes, both made by Chris Bishop. One has been able to handle an 11-34 cassette fine, but the other one only takes an 11-32 without bottoming out the b-screw and I still get the grinding from the upper jockey wheel being too close to the largest cog when in the 32 front-34 rear combo. Only other differences is I'm running a 32-48 chorus crank on one and a 34-50 record on the other, and a sram chain on the bike with the 34-50. Neither of those differences should change the fact that the derailleur pivot can't adjust enough to clear without the grinding.

Went to the shop near me to take a look and they suggested putting a wolf tooth extender on there, but none of their products are rated for 12 sp on paper, and an email to their customer service portal provided the same answer.

I could try to use their goat link or whatever, but they won't confirm that it will work or recommend it. Has anyone else used a similar set-up, or does anyone here know of another product that will get me some more clearance between the hanger and the rear derailleur?

Thanks!

[macaroon]

If you search "derailleur extender" on ebay, you should be able to find something for about $5.
Doesn't exactly answer your question, but it's cheap enough to test it out.

[Mark McM]

Before trying the derailleur hanger extender on, you may want to check if there are other adjustments that can be made. Specifically chain length: As you approach the limits of derailleur capacity (big-big and small-small), getting the chain length right becomes more critical. Is the derailleur stretched to its max when in the big-big combination? If not, then consider taking a link out of the chain - this will cause the derailleur cage to be extended forward more, and due to the offset of the top pulley, the top pulley will move downward as the cage is rotated forward.

Another little trick to increase the B-spring tension is to remove the B-screw and install it backwards, so the the head contacts the hanger. This effectively increases the length of the B-screw.

[vespasianus]

Originally Posted by Mark McM

Before trying the derailleur hanger extender on, you may want to check if there are other adjustments that can be made. Specifically chain length: As you approach the limits of derailleur capacity (big-big and small-small), getting the chain length right becomes more critical. Is the derailleur stretched to its max when in the big-big combination? If not, then consider taking a link out of the chain - this will cause the derailleur cage to be extended forward more, and due to the offset of the top pulley, the top pulley will move downward as the cage is rotated forward.

Another little trick to increase the B-spring tension is to remove the B-screw and install it backwards, so the the head contacts the hanger. This effectively increases the length of the B-screw.

That last idea is a good one and in the early days of MTB single rings, you could buy a large rear cog that would come with a longer B screw for Shimano derailleurs. Worked fine.

[shadco]

I’m thinking chain length too.

.

[herb5998]

Yes, chain length is probably a good starting point. For 12s, chain length is determined off of CS length, not sizing like in the past, so keep in mind it could be shorter than it should.

[chismog]

Originally Posted by Mark McM

Before trying the derailleur hanger extender on, you may want to check if there are other adjustments that can be made. Specifically chain length: As you approach the limits of derailleur capacity (big-big and small-small), getting the chain length right becomes more critical. Is the derailleur stretched to its max when in the big-big combination? If not, then consider taking a link out of the chain - this will cause the derailleur cage to be extended forward more, and due to the offset of the top pulley, the top pulley will move downward as the cage is rotated forward.

Another little trick to increase the B-spring tension is to remove the B-screw and install it backwards, so the the head contacts the hanger. This effectively increases the length of the B-screw.

This. In this order. You can also replace the B screw with a longer version from your local hardware store.

[sailorboy]

Originally Posted by Mark McM

Before trying the derailleur hanger extender on, you may want to check if there are other adjustments that can be made. Specifically chain length: As you approach the limits of derailleur capacity (big-big and small-small), getting the chain length right becomes more critical. Is the derailleur stretched to its max when in the big-big combination? If not, then consider taking a link out of the chain - this will cause the derailleur cage to be extended forward more, and due to the offset of the top pulley, the top pulley will move downward as the cage is rotated forward.

Another little trick to increase the B-spring tension is to remove the B-screw and install it backwards, so the the head contacts the hanger. This effectively increases the length of the B-screw.

Originally Posted by chismog

This. In this order. You can also replace the B screw with a longer version from your local hardware store.

These are good thoughts. FWIW, I did consider chain length and also asked the tech at the bike shop about it, and he as well as another guy both felt the chain length looked OK, but they didn't really put it in big-big/small-small, though I did. I might take a link out anyhow for the effect that Mark mentioned.

I like the thought of putting the b screw in backwards and will have to try that. I'm not 100% convinced tho only because as I put it in all the way normally, the end of it is actually jumping off the little step that it's supposed to push on so I'm not sure effectively making it longer will yield results. A picture would probably help to illustrate this but I'm too lazy to go take one. Maybe I'll do that later.

Thx for the tips so far.

And PS, thank you all for not pointing out the absurdity of having two steel Bishops with SR 12 speed. They actually have two different uses...really they do. lol

[chismog]

Dishing more on the chain length. I've set up several of my Campy bikes using "longest chain" method, ie I put it in small/small and make sure the rear derailleur can wrap it with some tension.

However, longest chain has given me problems trying to use 29 and 30t cogs with Campy 10. For most of my bikes, I had the same problem you reported (pulley rubs on cog) with longest chain. Pulling out one or two links does what Mark McM suggests, it tensions the derailleur enough to pull it away from the cog. But, you're often right on the edge with these big cogs... don't make the chain too short.

[KJMUNC]

So I have SR12 and 11x34 with 52x36 on both my Pegs. I’ve had similar issues with clearance on both, but mine was because the b-screw was pushing past the stop and not extending the derailleur. ….so my local Campy wrench suggested taking a small nut that threaded onto the b-screw and using Loctite to secure it. That nut is larger and now contacts the stop, so it acts like a larger b-screw and forces the derailleur further away from the cassette.

No issues with either for many thousands of miles!

[sailorboy]

Originally Posted by KJMUNC

So I have SR12 and 11x34 with 52x36 on both my Pegs. I’ve had similar issues with clearance on both, but mine was because the b-screw was pushing past the stop and not extending the derailleur. ….so my local Campy wrench suggested taking a small nut that threaded onto the b-screw and using Loctite to secure it. That nut is larger and now contacts the stop, so it acts like a larger b-screw and forces the derailleur further away from the cassette.

No issues with either for many thousands of miles!

Cool, that is someone using their noggin for sure. If I can find a tiny nut I'll give this a try as it seems like pretty low hanging fruit

[sailorboy]

Just to follow up on this in case anyone else has a similar issue, the idea of installing a small nut on the end of the b-screw has at least in the stand, done the trick with improving the shifting and stopping the grinding sound. I wanted to avoid breaking the chain and removing any links since it's a low-mileage campy chain and I don't have the tool to reconnect. Once it wears out I'll replace with sram 12sp since I've had good results on my other bike. I guess the only concern is if the nut comes off at some point but we'll see it the locktite does the trick.

[br0qn]

recently i was going through the campy 12 speed documentation for my own build and i recall reading the first production run rear mechs were designed for 32t cassettes before changing something and officially making them accept 34t cassettes. i was reading up on record and i think SR was the same. there is some code on the derailleur that signifies the change but i can't remember beyond that

[paredown]

Originally Posted by sailorboy

<snip> If it wears out I'll replace with sram 12sp since I've had good results on my other bike. ...

FIFY

(Good tip on the b screw too)

[marciero]

Originally Posted by chismog

This. In this order. You can also replace the B screw with a longer version from your local hardware store.

Originally Posted by KJMUNC

So I have SR12 and 11x34 with 52x36 on both my Pegs. I’ve had similar issues with clearance on both, but mine was because the b-screw was pushing past the stop and not extending the derailleur. ….so my local Campy wrench suggested taking a small nut that threaded onto the b-screw and using Loctite to secure it. That nut is larger and now contacts the stop, so it acts like a larger b-screw and forces the derailleur further away from the cassette.

No issues with either for many thousands of miles!

I've had this happen with long B screws. Years ago someone-Maybe Velo Orange?- was selling these as such, but certainly just a hardware store item. What happens is that as you screw in the screw and the deraileur moves away from the hangar/dropout it also rotates, and so the end of the screw may not align with the notch on the hangar. Mark McM's backward trick addresses this - accomplishes the same thing as a nut.