Campy 10 shifting issues - any ideas?

[jtbadge]

A buddy of mine has just had a fresh Campy 10 install, but is having some issues. Here are the facts:

-New cables used
-the frame has internal routing
-Shifts up cassette correctly
-When shifting down, he has to press the thumb lever once and then again to shift down one cog.
-Also when shifting down, it will always skip from the 3rd to 1st cog, passing the 2nd entirely
-That said, no sticking/binding in the thumbshifter itself

Things tried:
-limit screw and barrel adjustments
-different wheelsets and cassettes (my first thought was cassette spacers in incorrect order - I had this problem before where the second cog would be skipped)

I'm sure there could be an issue with friction/binding due to the internal routing, but do you guys have any other ideas?

[Mark McM]

That sure sounds like the symptoms of a sticky cable issue. In particular, if the problem occurs more strongly in the smaller sprockets (the derailleur return spring has less force in the smaller sprockets). Try this test: Push the thumb button. If the derailleur does not shift, try pulling the derailleur out by hand. If the derailleur can be moved out, and it then stays centered on the new sprocket, that implies that the derailleur return spring wasn't strong enough to pull the cable on its own. Even new cables can be sticky, if the cable and/or housing got kinked or crimped, or has tight bends, or is rubbing on something.

For other possible causes: Does the rear shifting differ between the front shifter being in the big and little chainring? If so, then another possibility is that derailleur cables got crossed around each other inside the frame. This would cause the front derailleur cable to tug on the rear derailleur cable, interfering with shifting.

[peanutgallery]

Crossed and or tangled cables in the downtube?

[ultraman6970]

To me sounds the usual problem with the carrier... one of the legs of it is cracked or broke.

But always 1st to check the rd hanger in case has a crack, second... friction somewhere....

3rd... there is a screw that holds the spooler, where the cable sits inside of the brifter, that spooler could be or lose or the cable head is not inside of the hole of the cable spooler, that makes the shifting to behave like to mention, the cable head create friction because is off... either way youo have to remove the lever and check, obviously if the lever has scratches in the black plastic around the spooler then you found the problem. How to fix it? dremel the head so it fits better, sits deeper.

If your friend put shimano cables pretty much this is the problem then. He needs to dremel the head to fit.

Hope this helps.

[FlashUNC]

G springs.

[Ralph]

it would only take a few seconds to see if it will shift by hand to the skipped cog. Then try putting some more pressure on RD spring by adjusting the B screw so chain is a tad tighter. I know you want upper pulley tucked up under the cog....but you can try this without taking anything apart. Chain too long....running slack without much RD spring pressure?

I like to try everything I can before taking it apart.

[cmbicycles]

Disconnect the cable, shift by hand pushing the derailleur up and down through its range. If it shifts fine by hand, its not the derailleur. Next hold the end of the cable in your hand and shift to check for resistance when shifting... you can often feel when there is cable drag when the cable is not attached at the derailleur. Then check the shifter. It could be the shifter itself needs some attention as mentioned previously, but it could very well be a cable drag issue.

[Dekonick]

Defective Groupo. I will gladly make sure it is 'properly' disposed of... ;) Kidding... Try greasing the cables and what everyone else has mentioned. I assume he used new cables and housings... but it never hurts to put a dab of teflon grease on the cables before running them into the housing.

Also just make sure the housing was cut square. Normally using a dremmel or a grinder to finish the ends after you cut the cable housing prevents sharp or crunched ends that can catch cables. Perhaps overkill...

[oldpotatoe]

You don't mention which '10s' group. What model and year? 2008 and older round shifter top Record or Chorus? 2009 and later 'gumby' levers? One higher gear at a time with thumb button shifters?
Spring carrier and shift 'g' springs mentioned. That might be true if the shifter's 'clicks-ness' is gone but if the shifter still feels stout, probably not.
I'd also guess drag somewhere and inside the frame or where it comes out great places to check.
If it's 'power shift' or 'escape', one higher gear at a time, might be bad shifter.
But if 'ultrashift' 10s, 2000-2008 any but Xenon, 2007/8 Record or Chorus, 2009 Centaur or Veloce...cable drag somewhere...frame, ferrules, routing, housing, broken strand, something.