Chain slip on 11t
 

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[Closed] Chain slip on 11t

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Despite trying everything I can think of, the chain still slips on the 11t sprocket under load. The story so far:

- New frame
- New chainring
- New chain
- New cassette (bollany from eBay)
- Changed 11t to an XT 11t
- Checked hangar is straight
- Checked outer limit screws
- Checked Shimano chain is the right way round (it wasn't originally)
- Checked Shimano quick link is the right way round

It's better than it was, but still jumps occasionally!


 
Posted : 25/03/2021 9:02 am
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B screw?

Insufficient chain wrap


 
Posted : 25/03/2021 9:07 am
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Chain too long?


 
Posted : 25/03/2021 9:28 am
 igm
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Too short a chain will affect chain wrap won’t it?

It does sound like chain wrap is of interest.

B-screw, goat link etc, chain length

Also, is the 11t sprocket properly seated


 
Posted : 25/03/2021 9:57 am
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Mine skipped in 11T months after setting up a new build. Chain was too long. Don't know why I hadn't seen it before, why it suddenly became an issue. Maybe the mech was tightened up rotated back, then slipped onto the B screw limit after some riding. Odd.

Took a link out, made sure everything was as it should be, rode fine for ages.

Started skipping in 11T again on a ride last week. Chain was slack again. B screw had slipped. Tighty-tighty, all fine again.


 
Posted : 25/03/2021 10:08 am
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Changed 11t to an XT 11t

A new one?


 
Posted : 25/03/2021 10:16 am
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Mine did it on a newish 12 speed build. As above, I needed to max out b-screw (beyond the guidance marks on the back of the cassette) to achieve sufficient wrap on the 10t.


 
Posted : 25/03/2021 10:24 am
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What's your chain line like?

Is it a boost frame with normal cranks and a boost kit on the hub?


 
Posted : 25/03/2021 10:37 am
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Chain length, B-screw setting and the design of the mech hanger can all effect the running on the 11t cog. The spec for where the mech bolt should be is vague enough that some designs can leave it too far back to wrap the smallest cogs effectively, especially on the early SRAM Eagle stuff. I would have thought that every manufacturer knows this by now though.

I remember Shimano stating the lack of chain engagement and wrap as the reason that they wouldn't go lower than 11t for a long time, wonder what changed their mind?


 
Posted : 25/03/2021 10:42 am
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XT derailleur?
Have you lubed the clutch pivot?

I've had an issue where the clutch doesn't provide sufficient tension on the chain. Shimano specify that you need to lube it occasionally, requires pulling it all apart, but it's in the maintenance manual online as isn't difficult.


 
Posted : 25/03/2021 10:56 am
 igm
Posts: 11833
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I assume chains that are too long or b screws that need winding in is where there is enough chain wrap but it’s a loose chain.

Whereas if there isn’t enough chain wrap it’s less b screw or more chain required.

That sound right?


 
Posted : 25/03/2021 11:40 am
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I don't think it's the b-screw. There's as much chain wrap as can be achieved and still get into the largest sprocket. Could be chain's too long? The chain line isn't ideal - I run a 36t up front with a 24t stealth granny for steep stuff. To clear the chainstay I've had to put a spaced on the drive side of the BB. Having said that, it's biased towards the smaller sprockets, which should help the 11t

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Posted : 26/03/2021 7:38 am

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