# Adjusting Campagnolo rear derailleur - no B screw or H screw



## Glyndwr (Sep 8, 2014)

I have an Athena triple group from (I believe) the mid-'90s with ergo shifters. The top pulley on the rear derailleur is rubbing on the cogs as I shift.

The derailleur would work perfectly if I could adjust the back tension, but there is no B screw to do so. I'm aware there is an H screw on modern Campagnolo derailleurs, down near the lower pulley, but my version doesn't have that either.

Any solution to my problem?

Thanks in advance.


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## gfk_velo (Jun 17, 2013)

Glyndwr said:


> I have an Athena triple group from (I believe) the mid-'90s with ergo shifters. The top pulley on the rear derailleur is rubbing on the cogs as I shift.
> 
> The derailleur would work perfectly if I could adjust the back tension, but there is no B screw to do so. I'm aware there is an H screw on modern Campagnolo derailleurs, down near the lower pulley, but my version doesn't have that either.
> 
> ...


Hi there ...
Athena Triple didn't really come into being until the 11s version in MY2012/13 ... what you have, if it hails from the mid 90s, is more likely "Racing Triple" as this was the Athena-level triple groupset of that era.
I just checked my memory against the archive at www,campagnolo.com as well as our own internal archive (which holds some info that Campagnolo in Vicenza don't) and all the RDs from 1994 (the first PDFs available) up to 2001 have a "B-Screw" type tension adjuster.
It's possible that at some stage the screw itself has gone walkabout but that the mounting sleeve with the tab it screws through is still in place, or although we have never tried it, it's possible that some of the later, non "B-Screw" type mounting sleeves will fit the older derailleurs and that the mounting sleeve has at some time been replaced with an incorrect part.
Do you ave any images of the derailleur? Given some pictures we *may* be able to help ...


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## Glyndwr (Sep 8, 2014)

Thanks. I have a small business building/restoring bicycles, and the client supplied me with the group. He may have been misinformed (or deceived) by the person who sold it to him, as far as the rear derailleur being part of the set, but the 3x8 shifters and brakes definitely are Athena, as engraved/labeled.

I realize by just reading my posting, you really can't just my experience level with such parts, but I am no beginner - maybe just not experienced with Campy triples! This one is a puzzler, as there are no mounts, and it isn't obvious if there is any part missing. Please see attached pix.


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## bikerjulio (Jan 19, 2010)

That's the same RD as a short cage that I have.

When you say the jockey is "rubbing on the cogs" do you mean all cogs? or just some, and in that case what size? Big ring or small?

My impression is that these have really strong spring tension, and that perhaps chain length is an issue.

I'm going to leave this to Graeme.


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## Peter P. (Dec 30, 2006)

What's the model number of the derailleur?

1995 Model RD-31AT; max cog 26T; total capacity 26T

1994/RD21AT/28T/26T

1993/RD11AT/28T/26T

1992/RD01AT/26T/26T

?/D010/30T/30T

The distance from the rear axle to the center of the derailleur mounting bolt must be 24mm for the above specs to apply.


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## Glyndwr (Sep 8, 2014)

The pulley rubs pretty much on all cogs while in any of the three rings.

Chain length is as it was taught to me long ago - wrap around largest cog and largest chainring, then add one full link.


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## Peter P. (Dec 30, 2006)

Glyndwr said:


> The pulley rubs pretty much on all cogs while in any of the three rings.


Is it possible the rear derailleur is malfunctioning and the B knuckle spring should be pulling the derailleur body BACK instead of forward? I'm not too familiar with Campy derailleurs. Is it also possible somebody swapped cages with another Campy derailleur and that cage does not work with that application? I've seen that done.


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## bikerjulio (Jan 19, 2010)

Glyndwr said:


> The pulley rubs pretty much on all cogs while in any of the three rings.
> 
> Chain length is as it was taught to me long ago - wrap around largest cog and largest chainring, then add one full link.


The H screw is a minor adjustment. Your problem is major. Something fundamentally wrong. Perhaps its with the frame stop rather than the RD?


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## tka (Jun 11, 2014)

It has been a while since I worked on one of those but if I remember correctly the only way to adjust the spring tension on the upper pivot is by disassembling it and placing the spring end in a different hole. You need to remove the retaining ring on the upper pivot, then carefully pull the backing plate away from derailleur body while holding it away from the stop, then unwinding it.


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## bikerjulio (Jan 19, 2010)

Was just playing with mine that's installed.

I'm going to agree with @tka that someone may have messed with the spring tension on the main mounting pivot. Mine runs out of tension with the upper jockey at the correct distance from the cogs.


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## Glyndwr (Sep 8, 2014)

There are no model number markings anywhere on the derailleur - only ID is the Campagnolo logo on the face plate.


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## bikerjulio (Jan 19, 2010)

Glyndwr said:


> There are no model number markings anywhere on the derailleur - only ID is the Campagnolo logo on the face plate.


One of my hobbies is trying to identify Campy parts.

I believe yours to be 1998 Athena as you were told. The logos to the right of the Campagnolo script have been removed. This was the first year the cable pinch bolt was allen key only. Additionally, 1997 and prior Athena had the Campagnolo logo centered.

This is the first time I've found Graeme to be wrong 

There was indeed an Athena triple in 1998, in fact it was an upfront feature in the catalog.


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## Glyndwr (Sep 8, 2014)

Thanks Bikerjulio! And I can't see a B screw on that derailleur either - now if I only could figure out how to adjust that pulley/cog distance.


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## bikerjulio (Jan 19, 2010)

Glyndwr said:


> Thanks Bikerjulio! And I can't see a B screw on that derailleur either - now if I only could figure out how to adjust that pulley/cog distance.


It's got to be the main pivot spring tension. Too high in your case.

ps "B" screw is a Shimano term 

Campagnolo has "H" screws and they work in reverse


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## cs1 (Sep 16, 2003)

In photo 3 it looks like the upper pulley has the wider 8 sp spacers. Maybe it's just the angle. The upper pulley is pretty worn out and bottom not far behind. Are they both genuine Campy? 

The B screw on the new style (post 2000) is the little gear on the back of the right hand knuckle. It should be under the black plastic cover. That means it's a current 9/10 not a 8/9 rear. Good luck.


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## Glyndwr (Sep 8, 2014)

I'm not sure what that spring even does without a B screw to anchor the derailleur. The whole sprung assembly area (circled in the photo) rotates, as it does on any rear derailleur, around the bolt that mounts to the hanger on the frame. The spring would provide tension between shifts allowing the derailleur to return to its proper location. The B screw pulls the derailleur back, increasing pulley distance from the cogs. Without that screw (like mine) the whole derailleur pivots forward, with that sprung assembly around the bolt serving no purpose.


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## bikerjulio (Jan 19, 2010)

Glyndwr said:


> I'm not sure what that spring even does without a B screw to anchor the derailleur. The whole sprung assembly area (circled in the photo) rotates, as it does on any rear derailleur, around the bolt that mounts to the hanger on the frame. The spring would provide tension between shifts allowing the derailleur to return to its proper location. The B screw pulls the derailleur back, increasing pulley distance from the cogs. Without that screw (like mine) the whole derailleur pivots forward, with that sprung assembly around the bolt serving no purpose.
> View attachment 311920


Yes, but as I said in one of my replies, on my RD of the same generation, the spring tension is over before it causes a problem. ie The RD does not pivot forward enough. It just stops.

With chain installed that is.


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## Glyndwr (Sep 8, 2014)

I found this blow-up on the Branford Bikes website. The part B on my derailleur is different, as it lacks the tab that would point towards the hanger, and serve the same role as a B screw (that's what Branford called it too, in reference to Campagnolo, and it doesn't work any differently than Shimano's, so sorry if the name game bothers anyone), except this would not be adjustable.
View attachment 311921
View attachment 311921


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## bikerjulio (Jan 19, 2010)

Glyndwr said:


> I found this blow-up on the Branford Bikes website. The part B on my derailleur is different, as it lacks the tab that would point towards the hanger, and serve the same role as a B screw (that's what Branford called it too, in reference to Campagnolo, and it doesn't work any differently than Shimano's, so sorry if the name game bothers anyone), except this would not be adjustable.
> View attachment 311921
> View attachment 311921
> View attachment 311922


The missing tab indicates that someone may have messed with it in the past. The tab indexes the RD to the frame meaning the whole thing can move around "more anti clockwise" than was designed. I'm left wondering if you are SOL as they say. The chain tension will just pull the RD around with nothing to counter it. 

Not to be argumentative, but the tab exists on all RD's. It's not the "same role as a "B" screw", because a "B" screw or an "H" screw provide adjustment, the tab does not.


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## darrenmoore501 (Mar 3, 2016)

*Same problem here: SOLVED*

I found this thread last night because I had the same problem with my Campa Chorus Rear Mech. I'd taken the circlip and spring out and hadn't reassembled it correctly. You have to get the end of the springs sited correctly so that they create the tension. One of the spring endings goes through the hole in the plate. Anyway thought I'd put this out there for any future searchers!



bikerjulio said:


> The missing tab indicates that someone may have messed with it in the past. The tab indexes the RD to the frame meaning the whole thing can move around "more anti clockwise" than was designed. I'm left wondering if you are SOL as they say. The chain tension will just pull the RD around with nothing to counter it.
> 
> Not to be argumentative, but the tab exists on all RD's. It's not the "same role as a "B" screw", because a "B" screw or an "H" screw provide adjustment, the tab does not.


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## looigi (Nov 24, 2010)

Without the tab, there's nothing to determine proper clocking of part B. When D is tight, is it possible to rotate B or does it become pinched and fixed? If it becomes fixed, it may be possible to set it clockwise some amount and tighten D to hold it in place...maybe?


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## bikerjulio (Jan 19, 2010)

looigi said:


> Without the tab, there's nothing to determine proper clocking of part B. When D is tight, is it possible to rotate B or does it become pinched and fixed? If it becomes fixed, it may be possible to set it clockwise some amount and tighten D to hold it in place...maybe?


My analysis is that the thing is allowed to pivot at the attaching bolt without any restraint, because the locating tab shown clearly on the exploded diagram as part "B" is missing on the photo (circled). Someone for some strange reason appears to have ground off the tab. The spring has nothing to work against. So there is no way it will work as it is.


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## bikerjulio (Jan 19, 2010)

I just looked at the 1998 spares catalog, which shows that there was both a locating tab and a "B" screw. OP showed the wrong parts diagram. My early '90's RD looks just the same.

Again, it's obviously been ground off in OP's example.


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