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skipping ultegra 10spd chain

I've just replaced cassette and chain. 

As previously I've put on a new ultegra 6700 10 speed 11-28  cassette and an ultegra 10 speed 6701 chain. Both bought from wiggle.   Running perfectly on my big ring but skipping under load on the small ring.  6700 SS rear derailleur. The skipping feels exactly the same as when there's a stiff link.  There isn't a stiff link.  The indexing is perfect.   Skipping in the mid gears.  The engraving on the chain links is on the outside, that is the chain's on the right way round.  What could be causing that?  

Grateful for any thoughts.

Richard

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15 comments

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Judge dreadful | 4 years ago
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Check the jockey wheels for damage / wear, and that they are in the right positions ( guide at the top, T pulley at the bottom ). Then make sure the chain is the right length, and that any slack is taken care of with a b screw adjustment if necessary.

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Pilot Pete replied to Judge dreadful | 4 years ago
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Judge dreadful wrote:

Check the jockey wheels for damage / wear, and that they are in the right positions ( guide at the top, T pulley at the bottom ). Then make sure the chain is the right length, and that any slack is taken care of with a b screw adjustment if necessary.

Err, if you read a couple of posts back he’s sorted the problem...

PP

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Thatsnotmyname replied to Pilot Pete | 4 years ago
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Pilot Pete wrote:

Judge dreadful wrote:

Check the jockey wheels for damage / wear, and that they are in the right positions ( guide at the top, T pulley at the bottom ). Then make sure the chain is the right length, and that any slack is taken care of with a b screw adjustment if necessary.

Err, if you read a couple of posts back he’s sorted the problem...

PP

...and it wasn't any of the things he suggested anyway  3

Also worth adding that the b-screw is not for adjusting chain 'slack' - which is not really a thing on a derailleur equipped bike.

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Pilot Pete replied to Thatsnotmyname | 4 years ago
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Thatsnotmyname wrote:

Pilot Pete wrote:

Judge dreadful wrote:

Check the jockey wheels for damage / wear, and that they are in the right positions ( guide at the top, T pulley at the bottom ). Then make sure the chain is the right length, and that any slack is taken care of with a b screw adjustment if necessary.

Err, if you read a couple of posts back he’s sorted the problem...

PP

...and it wasn't any of the things he suggested anyway  3

Also worth adding that the b-screw is not for adjusting chain 'slack' - which is not really a thing on a derailleur equipped bike.

it is if your chain is too long, or your derailleur cage too short or your cogs are too big a range! Agreed though, the B screw has nothing to do with any of them!

PP

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ktache | 4 years ago
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I didn't want to appear to insult your intelligence by suggesting it was probably the chainring because you had said it wasn't.  In a seperate post and everthing.

If a new chain is skipping you change the cassette, if it continues to skip then new chainring, then considering changing my chains sooner after taking the financial hit.

I cannot say if I have ever seen my chain skipping, it seems to only do it under heavy load, never on the workstand, usually pulling away at traffic lights or going up nasty little hills, more of a very disconcerting shocking feeling.

Though I have managed to change a several single sprockets to keep the rest of a few shockingly expensive cassettes going, knowing that it probably hasn't got long left.  A bit like putting a bit of lube into a freehub and building it back in to give you enough riding time to find a new one, and really kill the old one.

My KMC X1 EPTs seem to be at less than 0% when new using my chain checker.  So little side deflection too, tuff little chains.

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richardelliott | 4 years ago
2 likes

Kudos to all for kind suggestions but the winner is.....

KevJJ and PilotPete and Drinfinity - super kudos.  Despite my insistence that it was skipping on the cassette it wasn't it was as you suggested, on the small ring.  Switched another chainring/crank set over from another bike and bingo, all fine.  The clue I suppose was that there was nothing skipping when I was in the big ring.  With the benefit of hindsight perhaps pretty obvious but hindsight's a wonderful thing.

Anyway thanks very much all for your help.

Richard

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Drinfinity | 4 years ago
1 like

But I would be most likely thinking small chainring 

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Drinfinity | 4 years ago
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is the mech hanger perfectly straight? Is the rear wheel sat perfectly square in the dropouts? Cassette lock ring really tightly cranked down?

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Pilot Pete | 4 years ago
2 likes

If it doesn’t slip on the same cassette cogs when in the big ring it is almost certainly the little chainring. Check for worn teeth, bent teeth, etc. Can you get it to do it when on a workstand?

PP

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IanEdward | 4 years ago
1 like

Worn drivetrain components can be bafflingly hard to spot, it always seems like the problem is elsewhere!

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richardelliott | 4 years ago
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Thanks very much all, great suggestions.  Kevvjj -  I definitely hadn't clocked that and I just wonder.  Will get on it and let you know.

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kevvjj | 4 years ago
2 likes

I think you will find that it is skipping on the small ring and not the cassette. Had the same issu, was convinced it was skipping on the cassette, replaced the inner ring and all fine from then on.

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hawkinspeter | 4 years ago
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Tricky one. I'd have a good look at the derailleur and jockey wheels and check that the derailleur plate isn't upside down and that the chain is threaded correctly through them. Also, check that the cassette is done up nice and tight (somewhere around 40Nm if memory serves) and doesn't have any movement.

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vonhelmet | 4 years ago
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Obvious question, but is it routed through the jockey wheels correctly? If you get it the wrong side of the thingy it can skip a fair bit.

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richardelliott | 4 years ago
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I should add it's skipping on the cassette not the chainring.  Prob obvious but better to be clear.

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