Campy Chain skip - ideas please

[Clydesdale]

I have been trying to help a friend diagnos a drivetrain issue and am running out of ideas. He is a big strong rider on a Pegoretti Fina Estampa and basically when he pushes hard or especially stands up, he will get a skip in the cassette. Chain is good, cables are tight, cassette is in good shape, and the der. seems to be adjusted properly. He can ride the same gears without issue at higher cadences. He's monster strong, but I can't imagine he is torquing a Peg that much?

The only guess I have left is possibly something in the shift lever? Doesn't the Campy stuff have a spring that can wear out? He hasn't ridden a lot, but he says it feels like something moves under his grip just before the chain skips.

If the above guess sounds reasonable, how tough is it to get a new spring and replace/ rebuild the lever.

Any other theories are welcome.

[David Kirk]

There is no load or difference in load on the shifter regardless of how hard one pedals or what the cadence is. The shifter "see" no difference.

So IMO it's one of a few things -

* the rear derailleur cable tension isn't right causing any flex or movement in the system to make the bike try to shift into the next largest cog.

* the rear derailleur hanger is badly mis-aligned which will feed the chain onto the cassette in a funny way made worse but system flex.

* lastly.............. and this is the one I'm putting my money on. The chain is just plain worn out or it was recently with a new one on a used cassette. New chains must be accompanied by a new cassette.

Dave

[thwart]

I'm betting on #3 above as well.

Classic sign of a cog tooth or two that's a little too worn... if it's a loose cog cassette you can replace the one that tends to skip, or just throw on a whole new cassette to 'confirm the diagnosis'.

[Peter B]

Another vote for #3. Try replacing the cassette and I'l bet the skipping stops.

[Dave]

From the description, the chain is moving to another cog under high chain tension. That is not chain skip. Chain skip occurs most often when a new chain is installed on worn-out cogs. The chain will not mate with the most worn cogs (usually only 1-3 cogs). Instead, the chain skips over the top of the teeth and won't transmit power. It might also move to another cog during this process, but not usually.

The greatest chain tension occurs in the little ring, when standing to climb. That's when chain skip is most likely to occur, but if the most worn are smaller cogs, not many people would use the little ring with them. My most-used cogs are the larger cogs used for climbing.

Once in awhile someone will use a wipperman chain or their connex link and have it installed upside down. That will cause skip in the smallest cogs.

A new chain does not always require a new cassette, but it does if the old chain was used for too long without changing or the cassette has already been used with several chains. Eventually a new one will skip.

If the real problem is ghost shifting, then check the RD alignment and cable tension.

[Pete Serotta]

chain worn and/or specific cog on cassette...



There is no load or difference in load on the shifter regardless of how hard one pedals or what the cadence is. The shifter "see" no difference.

So IMO it's one of a few things -

* the rear derailleur cable tension isn't right causing any flex or movement in the system to make the bike try to shift into the next largest cog.

* the rear derailleur hanger is badly mis-aligned which will feed the chain onto the cassette in a funny way made worse but system flex.

* lastly.............. and this is the one I'm putting my money on. The chain is just plain worn out or it was recently with a new one on a used cassette. New chains must be accompanied by a new cassette.

Dave

[92degrees]

Just a thought -- check that the QR is tight and also that the cassette is not loose.

[PBWrench]

I have experienced that problem and the culprit was the Connex link as identified by Dave. Good luck, PBW

[Ahneida Ride]

#3

I am betting that that Professor Kirk is correct ..

I had the same issue ...

New chain + new cassette and Bingo ... no problems .... :banana: :banana:

[JumpStart]

Another #3.

Does it skip on all cogs? My history with chain-cassette issues usually involved a new chain with skipping limited to the cogs I tended to use most/had the most wear.

[Kirk007]

Another small possibility to check: Is the cable housing cut too short from the chainstay stop to the rear D stop? If it isn't making a nice arc that can throw off the shifting.

[rockdude]

One other issue it could be is a slightly bent chain link. I has a similar problem that drove me crazy until I found the bent link.

[Clydesdale]

The chain was recently replaced but the skipping was not resolved. I'll try a different cassette and see if it solves the problem. It happens most often in the big ring throughout the middle cogs. The cassette looks ok to me, but it almost sounds like that has to be it.

Appreciate the help.

[92degrees]

I've had that. I'm telling you, the cassette is loose and it's moving around under load.

[sspielman]

One other thing to look at...If it is a Veloce or other loose cog cassette...since the guy is big...if the cassette body on the hub is indented badly by the cogs, they could move about enough to make something skip under load...just another possibility that is not intended to detract at all from the comments by the King of Chains, Dave...(who is ALWAYS right on these things)

[David Kirk]

The chain was recently replaced but the skipping was not resolved. I'll try a different cassette and see if it solves the problem. It happens most often in the big ring throughout the middle cogs. The cassette looks ok to me, but it almost sounds like that has to be it.

Appreciate the help.

With all due respect one can't look at a cassette and tell if it's OK. If the cassette is used and the chain is new their is your problem.

The best thing to do IMO is buy a new cassette and two chains. Alternate the two chains to minimize wear on all the parts in question. You cassette can then last longer than one chain.

Otherwise......... put on a new cassette and chain at the same time.

Good luck.

Dave

[Clydesdale]

I'll get him set up with a cassette and hopefully that will take care of it.

Man it's great to have a place to ask questions and gain some wisdom - thanks all.

[Samster]

chain. cogs. rings. screw em. time for a new gruppo.

[caleb]

I
The only guess I have left is possibly something in the shift lever? Doesn't the Campy stuff have a spring that can wear out? He hasn't ridden a lot, but he says it feels like something moves under his grip just before the chain skips.


It's probably the cassette. If that doesn't work look at the shifter.

Is it shifting to a larger or smaller cog? If smaller, it might be the shifter - here's how you can tell:

1) Grab the exposed cable on the downtube.

2) Pull lightly.

If cable comes out easily, he has a broken spring in his shifters.

Note: even a new lever will release cable if you pull hard.

[dogdriver]

Long shot, but take a good look at the cassette-- one of the cogs may either have a damaged tooth or an entire cog may be bent. More of an mtb issue, but its worth a look.

Cheers, Chris

[TimD]

One of my regular crew had a similar issue, perhaps not the same. After trying various remedies he disassembled the cassette and found the spacers were not installed correctly.

I have not verified this, but the claim is that Campy (10, I think) cassettes use spacers of different thickness, which must be installed between specific cogs. He identified the problem, and the correct installation order, after reviewing an online exploded diagram of the cassette.

YMMV!
Tim

[Dave]

Yes, there are different thicknesses of spacers. The cassette comes with instructions that explain this or they can be found at www.campagnolo.com. This could cause shifting problems and perhaps even ghost shifting, but not chain skip.

[Erik.Lazdins]

#3 has happened to me

A used cassette with a new chain will skip under power