Chain Slip advice

by pablo   May 2, 2014  

Hi all,

I've been reading for a while and thought it was about time a joined the forum especially as i have an issue i can't figure out.

I've recently started to get some chain slip after i change gear and was hoping for some opinions on what could be the cause. The chain doesn't actually slip as i change gear it happens later mainly when a have a cheeky rest and then start pedalling again. It won't do it again until until i change gear and seems to happen in the big or small chain ring at the front. The rear cassette has just under 1000 miles on it and the chain has just been changed (did it on the old chain as well). The gears index fine with no real hesitation.

The only thing i can thing of is maybe gear cable tension but i would have thought i would have problems when changing gear with hesitation. Any ideas i what i should check? Oh it's ultegra 20 speed.

Cheers Paul

10 user comments

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Cable tension wont be a factor is it is indexing fine.

I'd look for wear on the cassette, it sounds to me like that is worn. If it is only slipping the once on every change, it could mean that you have one link to many in your chain, stick it in the big ring and the biggest cog, see if there is any excess slack in the chain.

If there is no wear on the cassette and no slack in the chain. It could be a rear mech issue.

Gkam84's picture

posted by Gkam84 [9038 posts]
2nd May 2014 - 19:04


One assumes it is the correct chain for the cassette and that the chain rings are not worn out?

All Campag

posted by Flying Scot [670 posts]
3rd May 2014 - 10:42

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The cassette is a 10 speed ultegra with a new ultegra chain. Had a look at the bike this morning couldn't see anything obviously wrong. I have adjusted the B-screw slightly to bring it closer to the cassette.

Could the chain be to long? It's the same length as the old one but i change cassettes occasionally from a 11-25 to a 11-28 (i think it is anyway its what came on the bike) . I've been running it for months without issue. The rear derailure looks in the right position when in the middle of the cassette.

I'm doing a sportive tomorrow and i think they have mechanic support think i will ask them what they think.

Cheers for the replies.

posted by pablo [34 posts]
3rd May 2014 - 12:50


Are you sure it is not the freewheel? I thought i had chain slip but it was one (or more) of the ratchets in the freewheel not engaging properly. Major hub overhaul rectified things.

posted by veseunr [282 posts]
7th May 2014 - 7:37

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pablo wrote:
The cassette is a 10 speed ultegra with a new ultegra chain.

A new chain on a worn-out cassette can easily cause chain slip; the worn teeth don't mesh correctly with the new chain. Was the drivetrain well-maintained, i.e. regularly cleaned and lubed, or was it left until it didn't really shift properly anymore and a new chain slapped on? If the latter, I'd suspect worn sprockets. Is the problem worse in your most-used gears?

posted by srchar [60 posts]
7th May 2014 - 13:47

1 Like

Thanks! You may have identified my problem. I tried adjusting the cable, changed the chain and hanger but although it feels like the chain jumping I can't actually see it happening. What should a hub rebuild cost me?

Tovarishch's picture

posted by Tovarishch [49 posts]
7th May 2014 - 14:04

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Tovarisch, Changing the cassette is fairly simple, once you have the right tools - which are maybe £20. You need a chain whip, a cassette lock ring tool, a socket-wrench suitable for the lock ring tool , and a little bit of strength. Ideally, your socket wrench should be a torque wrench in the 100 Nm range, otherwise you have to tighten by feel (luckily cassette lockrings tend to self-tighten with use).

An Ultegra cassette is around £50, though Wiggle have some on sale at the moment for less.

A half decent LBS should be able to do this in 5 minutes, for not too much labour. If you buy the cassette from them, I'd hope they'd fit for free.

posted by Paul J [675 posts]
7th May 2014 - 14:58


As someone else has noted if it's doing it on every sprocket after you have been freewheeling and then re applying drive then it's possibly the free hub body. Grease can dry out, there isn't a tool available to take a freehub body to bit's anymore as Shimano stopped making them but you can fabricate one from steel tube if you are skilled enough. Failing that a soak in teflon oil has been known to soften the grease up again and un-stick the pawls but that's a temporary fix as you are washing some of the grease out at the same time. Doing that or replacing the freehub body it's still full strip down of the hub.

posted by MKultra [285 posts]
8th May 2014 - 10:09


I would look at the gear hanger alligment

posted by jason.timothy.jones [303 posts]
8th May 2014 - 11:06


jason.timothy.jones wrote:
I would look at the gear hanger alligment

I agree with this. I hired a (great) bike for a couple of weeks over the summer. It bothered me no end that in most gears, everything was super smooth, but at either one or other end of the cassette (depending on the tension adjustment), the chain would skip/slip a bit. Only in the last couple of days did I work out that the rear hanger had been bent a little (bike must have fallen over onto the rear derailleur before I hired it). Some gentle straightening made a bit improvement

The other time I have had unusual chain skip was when my jockey wheels in the rear derailleur had work away into shark teeth shaped points, instead of the usual trapezium-shaped cogs.

posted by Tjuice [124 posts]
8th May 2014 - 23:07

1 Like