Ok. I'm really stumped here.

I'm running Campagnolo 10 speed(Record shifters and derailleurs) and the shifting is terrible. When I dial in the rear derailleur to shift perfectly up the cassette ie 11-23 then when I downshift 23-11 the derailleur lands between cogs. example: shifting from 16-15 the derailleur lands off center toward the 14 and the chain makes noise rubbing against the cog. If I up the tension enough to make it quiet then the problem is the exact opposite + a nasty over shift before the chain comes back down to the correct cog.

So far I have tried new Campagnolo cables, new Centaur chain, new Centaur cassette, new g springs and alloy carrier, new Campagnolo BB cable guide, derailleur hanger alignment, and finally a complete rebuild of the right shifter.

Ive also tried the friction test that Campagnolo has a video of on their website along with running the cables in front of the bar and then around the back. No matter what I do the problem is still the same.

Any help is appreciated.
Thanks

For the rear der....differences going up vs down I always look at cable friction first.....I'd suggest doing the campy test again just to be sure.

But if that's not the issue I'll also suggest double checking to see which side of the cable attachment bolt is the cable resting - on the lower side or up on the higher side?

If accidently on set the high side of the bolt it will increase the amount of derailleur movement for any given amount of cable movement.

Thanks Tommasini. It's on the lower side.

Bent derailleur hanger?

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Cervelo R3, Campagnolo Chorus/Record mix... pastatrails.blogspot.com
And you can call me Macktastik Honey Pete Kicks, thank you.

I would check a couple of things:

That the initial setup was correct. ie cable off, thumb shifter released, RD nicely aligned using the limit screw, reattach cable with a little tension.

Correct assembly of cassette, ie with correct spacers.

Hanger alignment. Since I bought the tool I found lots of misalignment.

Cable issues are not rocket science. Simply hold both ends and move it through the range. should feel easy.

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dangerous curves ahead

Not the alignment. I have the park alignment tool, and check my bikes everytime the derailleurs are removed.

I don't think it's cable friction because I took good care to clean up the ends of the housings and routed the cables for the widest turn I could. Also, it shifts perfectly in either one direction or the other. Cable friction would leave it shifting inconsistently.

I disassembled everything again and set the derailleur up in line at both ends then added the cable, gave it 3 clicks then increased the tension to line up the derailleur on the 4th cog. Still the same issue with it moving more in one direction than the other.

I'm beginning to think it is something with the derailleur, but cant imagine what could be worn. I bought the derailleur used off ebay, but it is in near mint condition, without any detectable play. I've also added new jockey wheels.

Possibly a broken G spring in the shifter?

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"It never gets easier, you just go faster..." - Greg Lemond

"Because technology alone is a poor substitute for experience." - Richard Sachs

Or the detent thing that the g-spring sits into can actually wear and cause issues. They are cheap as chips and pretty easy to install. (they are available as a replacement part)
Did you have it all working sweetly before you changed the rear derailleur?

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Used to race....got too wrinkly and old Updated: Racing again! Thought this was unlikely! Eventually, I may even have a decent race!

I never changed the rear derailleur. I pieced the group together off ebay. It never shifted right, so thats when I started to change parts and eventually bought a complete rebuild kit from Branford Bike which is everything except the brake levers and hoods. The shifter is basically brand new. Before I bought the complete overhaul kit I did change the G springs, carrier, and washer. Didn't work, so I got the complete overhaul.

Cable friction could give exactly this effect. Perfect downshift, sluggish and incomplete upshift. Adjust to shift up nicely and it doesn't quite pull enough to downshift nicely.

If cable friction has been eliminated it is most likely friction elsewhere. This could be in the lever or the mech pivots themselves.

To test the mech, remove the cable and push the derailleur in to shift one sprocket. When you release it, you should get a quick, perfect upshift. If you don't, the mech pivots have resistance. I must add, this is unlikely to be the cause as it usually cannot be "dialled in" to give a consistant upshift, especially in the higher gears. If this proves ok, it is most likely friction in the shifter.

Ferrule on the end of the cable inside the ergoshifter?

I have ferrules on the both ends of the cable. I installed the cable per Campagnolos instructions ie cut excess off from the opposite end of the pre installed ferrules and insert the pre installed ferrule end into the shifter.

I just adjusted the derailleur to shift perfectly going up the cassette. I shifted into the 4th cog then shifted into the 5th and then the 6th cogs by pulling the cable along the down tube with my hand. When I released the cable the derailleur fell exactly where it should have on the 4th cog. Next I shifted from the 4th to the 5th then 6th cogs with the shifter this time using thumb shifter to drop back down to the 4th, and no surprise it overshifted and made noise. What is surprising is that while the derailleur was overshifted and the chain was making noise rubbing on the number 3 cog I again pulled cable at the downtube with my hand to shift up to the 6th cog and then released it, and the derailleur fell back to being perfectly inline with the 4th cog.

Just for a background on the shifter. I bought a shifter off ebay. I wasn't happy with the shifting, so I changed g springs, carrier and washer, but there wans't any change in shifting. Next I bought the complete rebuild kit. The shifter is essentially brand new. The rebuild kit came from Branford bike completely assembled, so all I had to do is add my brake lever, hood, and clamp. The new shifter doesn't shift any better than the one I bought off ebay.

Is it possible that in taping your cables to your handlebars that in combination with the shifter body position on the handlebar that the cable housing is not fully seated to the bottom of the female reciever? (one way to check is take the tape off that is holding the housing to the bars).

No cable ferrule in the body of the shifter - correct?

No, I have a cable ferrule inside the shifter body. Is there not supposed to be one there?

Also I have undone the tape that holds the cable housing to the bars to reduce any friction from the bend in the housing while I sort this out.

Your cable is getting snagged somewhere or (as mentioned above ) the spacings are wrong on the cassette. Its easily done and produces exactly the cause you have outlined.