chain jumps at jockey wheel - but only on smallest rear cog

[lpretro1]

It's not something daft like a mudguard bolt that's too long and sticking through the eyelet too far - have seen that several times

 

[andrew_s]

Wipperman/Connex connector links have to be put on the right way round, or they will cause skipping. The link rides up on the lockring and lifts the chain enough to allow the skip.

 

[Smurfy]

I'd say a stiff link although you have already checked for that.

yeah that was my initial thought as well but the chain is clean well lubed and every link is free...my money is on the lock ring...sounds aboiut the only thing left i didnt check yet...

Have you tried slowly back pedalling by hand and watching for a link jumping?

If it's the same link every time it's the chain.

If it's the same sprocket tooth every time it's the sprocket.

 

[Globalti]

I've had something like this for a few months now and have given up trying to solve it. Chain on the big ring and the 11 cog; I give it some beans and very occasionally the chin will skip with a loud crack. I replaced the chain and it didn't cure the problem; I fitted a new cassette and it still wasn't cured. Derailleur is properly adjusted with no clattering and the stop screws adjusted right so I'm defeated. I will borrow my neighbour's alignment tool and check the hanger alignment.

 

[ricnott]

Are you using a quick link or chain pin. I had a chain pin that wasn't properly installed and the tight clearance may be causing the click if so.

 

[lpretro1]

Good call ricnott

 

[ufkacbln]

I agree with others about a stiff link

This would be reaffirmed by the fact it occurs at the points where the radius is at the smallest

Get some tippex and slowly move the chain through the system

When the jump occurs mark the chain

Repeat, and if it recurs at the same position it is the chain link

Whether that is the link or pin can be investigated with accuracy

 

[mickle]

Replace the bike obvs.

 

[Racing roadkill]

In what way is it "worth changing them with every chain / cassette change"? What is the 'business case' for this frequency? Why not more often? Or less often? To what extent does the performance of jockey wheels deteriorate? How do you measure this? Or is this just your arbitrary rule of thumb? Do you change brake cables when the blocks need replacing?

 

[Levo-Lon]

Accidentally fitted a 10s chain link ?
The 11 is .4mm narrower so a 10s link will catch..or the pin as sugested..
has a plate seperated slightly? Have a close look

 

[Smurfy]

I've had something like this for a few months now and have given up trying to solve it. Chain on the big ring and the 11 cog; I give it some beans and very occasionally the chin will skip with a loud crack. I replaced the chain and it didn't cure the problem; I fitted a new cassette and it still wasn't cured. Derailleur is properly adjusted with no clattering and the stop screws adjusted right so I'm defeated. I will borrow my neighbour's alignment tool and check the hanger alignment.

Eleven tooth doesn't have much chain wrap around, so it seems possible that a sprocket this small only works when everything is perfect. Combined with a lot of pedal pressure and a bump in the road, this could be what is allowing a brief skip. You could try adjusting the angle of dangle screw (A in the image below) to try and improve the wrap.

 

[Globalti]

That's a good suggestion, thanks.