Need campy rd adjustment help-upper pulley hitting cogs

[John M]

I have installed and adjusted several campy 10 RDs, but I am having trouble with a 2009 centaur 10 RD upper pulley hitting the cogs when chain is on the small chainring on a Parlee TT with track end type dropouts. The RD hanger appears to be within campy recommended spec for dimensions. I have the H-screw ("B" screw) all the way out, which should pull the upper pulley down as far as it goes. The RD top pulley is hitting the cogs in all gears when on the road, but not in the stand. When chain is on the large chainring, things are OK.

Chain length is correct and this RD worked perfectly on my Merlin Agilis.

Suggestions?

[ceewho]

It might be helpful to get a longer replacement B tension screw. I did that on my Shimano RD before. You using some huge rings?

[John M]

You using some huge rings?

This is technically not a "B" screw as would be found on the Shimano RD's or pre-2001 Campy RD, but is the screw on the upper pulley pivot.

53/39 with 13-26 10s cassette

[cmg]

here's a link that will give you an idea. http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur look for a small screw on the upper body near the upper pulley. look at this thread for a photo http://forums.thepaceline.net/showthread.php?t=131895 adjusting this screw will move the pulley in relation to the cassette.

[giordana93]

I hate to second guess you about chain length, but if all else fails, you might take out an extra link or so and make it as short as possible. A bit of extra tension can go a long way.

[Ralph]

I hate to second guess you about chain length, but if all else fails, you might take out an extra link or so and make it as short as possible. A bit of extra tension can go a long way.

Assuming hanger right length.....Taking a couple links out of the chain can pull the upper pulley back out of the way....to clear the biggest cog. But don't know if you will have enough chain to then wrap big to big. A 30 tooth rear cog pretty much maxes the Centaur short cage out. Or about a 30-32 tooth difference (small ring to big ring difference plus small cog to big cog difference) under good frame conditions. You should have no problems with a 39/53 and 13-26. I've run a 39/52 and a 12-30 with that RD.

[oldpotatoe]

I have installed and adjusted several campy 10 RDs, but I am having trouble with a 2009 centaur 10 RD upper pulley hitting the cogs when chain is on the small chainring on a Parlee TT with track end type dropouts. The RD hanger appears to be within campy recommended spec for dimensions. I have the H-screw ("B" screw) all the way out, which should pull the upper pulley down as far as it goes. The RD top pulley is hitting the cogs in all gears when on the road, but not in the stand. When chain is on the large chainring, things are OK.

Chain length is correct and this RD worked perfectly on my Merlin Agilis.

Suggestions?

I think your chain is one link too long...

[John M]

Thanks all. I swapped over a mid-cage RD from another bike as an experiment to effectively "shorten" the chain and it cured the problem. Chain is a bit tight in the big-big combination, which I don't use anyway, so looks like I will be good to go with the short cage RD and if I take a link or two out of chain. Increased chain tension seemed to be trick in pulling the RD down and forward just a few mm.

Again--thanks for the advice.

[Hindmost]

Chain is a bit tight in the big-big combination...

You are having trouble with a 53/39 and a 13/26? Something is amiss. I would be wary of not having enough chain for "big-big".