Campy 10 B-screw. Help please

[PeterF]

I switched recently from a 12/25 to an 11/23 cogset and when I'm in my 19-21-23 cogs, it feels as if the there is a bit of chain slop. Everything shifts fine, my H and L limits are set fine and everything lines up perfectly, laterally speaking. I was reading the literature that I received with my rear derailleur ('04 Campy Record 10) and it just isn't very clear (the devote one sentence to the b-screw). It is saying that if the derailleur cage (?) is touching the largest cog to back the b-screw out until it is no longer touching. Dumb question warning: I'm assuming this means I should remove the chain (no problem since I have a connex link and I take it off to clean it a few times a season) and set the b-screw tension, correct? If so, what am I looking for? With no chain and the derailleur set to the largest cog how much distance should there be between the upper jockey wheel and the cassette? I have always run a 12-25 so I've never had to adjust the b-screw since it was first installed. I'm no stranger to a wrench having built three bikes from the bare frame, but I'm not too familiar with b-screw adjustments. Help please. Thanks.

Peter

 

[hd reynolds]

The 'B' screw controls the gap between your cogset and the upper pulley of your rear derailleur. The closer the upper pulley (with the chain of course) to the cogset, the more accurate the shifting becomes. However, sometimes the gap can be so close on the smaller cogs that it overlaps the bigger cogs when shifting to these. If this is the case, shift to the bigger cogs it overlaps and screw it on until there is a gap. Having said this, sometimes there may not be a noticeable gap created as you screw it on, just screw it on then shift up to the lower gears and then shift back to the bigger cogs (put the bike on a stand whereby you can operate the pedal and shift with your free hands). The shifting should improve as you adjust the B screw. Tweak the adjustment until you get smooth shifting action you're happy with.

 

[alfeng]

I'm assuming this means I should remove the chain (no problem since I have a connex link and I take it off to clean it a few times a season) and set the b-screw tension, correct? If so, what am I looking for?

FWIW. I find that it is easier (as in FASTER, for me, at least) to adjust the B-screw when the derailleur is not attached to the frame ... with the wheel out, but with the chain still looped through the pulleys ... otherwise, you are (that is, "I am") fighting the derailleur's recoil (whatever it is called) spring.

Oh, without meaning to state the obvious, the B-screw is the one nearest to the derailleur hanger, and it subsequently adjusts the angle of the parallelogram ...

 

[alfeng]

I switched recently from a 12/25 to an 11/23 cogset and when I'm in my 19-21-23 cogs, it feels as if the there is a bit of chain slop.

BTW. If you aren't going to be swapping back-and-forth between cassettes, then you can remove 1" of chain (two links) ...

 

[PeterF]

BTW. If you aren't going to be swapping back-and-forth between cassettes, then you can remove 1" of chain (two links) ...

Thanks. Recent knee problems will have me putting in a 13/26 cassette to give me a spin option up some of the steeper climbs I deal with. Like I said before, the shifting is fine, I'm just trying to get the proper gap.

 

[Eastway82]

Oh, without meaning to state the obvious, the B-screw is the one nearest to the derailleur hanger <snip> ...

Don't think so – on all Campag rear ders since 2001 (I think), the screw in question is down by where the pulley cage pivots on the body. Earlier ones had the screw in the traditional place by the derailleur hanger.

 

[PeterF]

Don't think so – on all Campag rear ders since 2001 (I think), the screw in question is down by where the pulley cage pivots on the body. Earlier ones had the screw in the traditional place by the derailleur hanger.

Mine's an '04 and it's on the pulley cage as you described.

 

[alfeng]

Don't think so – on all Campag rear ders since 2001 (I think), the screw in question is down by where the pulley cage pivots on the body. Earlier ones had the screw in the traditional place by the derailleur hanger.

Thanks for the correction ...

I guess it's time I bought a new rear derailleur!

 

[CAMPYBOB]

I guess it's time I bought a new rear derailleur!

nah! old campy's never die! they just get installed on classic, vintage and retro bikes!

 

[Eastway82]

nah! old campy's never die! they just get installed on classic, vintage and retro bikes!

yeah - if it still works, who needs a new one...? I hate the whole throwaway culture thing. I'd much rather keep things working and mix and match, and I've seen a couple of pics of Alfeng's bikes and I know he does just that!

 

[Calvin Jones]

The Campagnolo B-screw is on the lower pivot. The upper pivot spring is fixed. The two springs oppose each. Loosen the B-screw here to move the upper pulley away from the cogs. Tighen the B-screw to move the pulley closer.
See http://www.parktool.com/repair/readhowto.asp?id=64

Also see http://www.parktool.com/repair/readcalvinscorner.asp?id=154

 

[hd reynolds]

The Campagnolo B-screw is on the lower pivot. The upper pivot spring is fixed. The two springs oppose each. Loosen the B-screw here to move the upper pulley away from the cogs. Tighen the B-screw to move the pulley closer.
See http://www.parktool.com/repair/readhowto.asp?id=64

Also see http://www.parktool.com/repair/readcalvinscorner.asp?id=154

You got it mixed up Calvin, you TIGHTEN the B screw (campy or non-campy) to move the upper pulley away from the cog and vice versa.

 

[Eastway82]

You got it mixed up Calvin, you TIGHTEN the B screw (campy or non-campy) to move the upper pulley away from the cog and vice versa.

Nope, he's right - for 2001-on Campag it's the other way round.

 

[hd reynolds]

Nope, he's right - for 2001-on Campag it's the other way round.

Looked it up and yes you're both right... and campy calls it ''a'' tension now!?

Campagnolo Rear Derailers

2001 and later Campagnolo rear derailers don't use a "b tension" adjustment. Instead, they have an "a tension" adjustment. Spring balancing is done with this adjustment, but in the opposite direction. That is, loosening the "a tension" has the same effect as tigntening the "b tension." - sheldon brown