Poor rear shifting, worn out Jockey Wheel?

[fossyant]

New cables, inners and outers.

 

[Noodle Legs]

+1 for the cables and housings, a drop of lube on replacement can help too.
Just putting it out here but try moving the cage laterally with your hand. If there is excessive movement then this is a sign of a worn mech which, like a bent hanger, will make it very difficult if not impossible to index properly. If this is the case, consider a new mech.

 

[Globalti]

Also check the bolt, which holds the derailleur onto the hanger. They have no elasticity so can work loose easily.

 

[screenman]

I know it’s a bit of a laugh but @screenman is right about this. I bought the alignment tool and all bikes I have used it on needed some hangar adjustment, it does fix a host of gear issues and noisy rattly transmission.

Not many people are prepared to listen to us on this one, they go for the things they can see rather than the very important one's they cannot. I have never once had a cable issue only give problems in the middle range, I have rear mechs over 20 years old with floppy jockey wheels that still give great changes.

 

[screenman]

Sticky cable can be a problem when it is required to be slack, not midrange.

 

[Globalti]

Yes, mostly dropping on to the smallest cogs when the derailleur tension is lowest. But a sticky cable will also mess up your indexing.

 

[GoatBeard]

Seems like a process of elimination here, start with cables, then hanger, then mech, then bike, then rider! etc etc. Trouble is it's a second hand bike so I'm just not entirely sure what to expect in terms of wear and tear. Thankfully the jockey wheels aren't anywhere ninja stars. I was just wondering if the shifting weirdness on big ring and the 3rd/4th biggest cogs might point to something specific. They aren't worn down by any means. Hanger is suspect but I just can't gauge it by eye. Should probably start with a new inner and a hanger then look to replace the mech if I get nowhere with that.

Did notice the B screw seems to have no impact on the positioning of the chain to cog gap?

 

[screenman]

Seems like a process of elimination here, start with cables, then hanger, then mech, then bike, then rider! etc etc. Trouble is it's a second hand bike so I'm just not entirely sure what to expect in terms of wear and tear. Thankfully the jockey wheels aren't anywhere ninja stars. I was just wondering if the shifting weirdness on big ring and the 3rd/4th biggest cogs might point to something specific. They aren't worn down by any means. Hanger is suspect but I just can't gauge it by eye. Should probably start with a new inner and a hanger then look to replace the mech if I get nowhere with that.

Did notice the B screw seems to have no impact on the positioning of the chain to cog gap?

Just get the hanger checked, no need to buy a new one.

 

[raleighnut]

Seems like a process of elimination here, start with cables, then hanger, then mech, then bike, then rider! etc etc. Trouble is it's a second hand bike so I'm just not entirely sure what to expect in terms of wear and tear. Thankfully the jockey wheels aren't anywhere ninja stars. I was just wondering if the shifting weirdness on big ring and the 3rd/4th biggest cogs might point to something specific. They aren't worn down by any means. Hanger is suspect but I just can't gauge it by eye. Should probably start with a new inner and a hanger then look to replace the mech if I get nowhere with that.

Did notice the B screw seems to have no impact on the positioning of the chain to cog gap?

If you fit a new hanger it will still need to be aligned correctly