My SRAM gears (X9 derailleur ) is imprecise in gears 8 / 9 /10 …. it suddenly jumps… but only in these gears…..

… and it is also just a bit hesitant to change …. not snappy…

I’ve tried adjusting the cable …. tried tightening and loosing but neither seems to make any improvement…..

Any ideas?

New chain and cassette will solve it, maybe new rings needed too.

I’m guessing the jump is when you are outing a bit of power down?

no… its not necessarly under power…. and not even consistent!…. its started dong it last week for no apparent reason!

How old are the cables? Sounds like sticky cable release to me

How old are the cables? Sounds like sticky cable release to me

I’d be trying that before the chain, rings and cassette! It’s often worse in 8/9/10 because that’s where the spring is under least tension.

Check the mech hanger is straight….you may have banged it without realising

Jump as in skipping round the cassette, or jumping between the gears?

If it’s the former then either badly worn (new chain on old cassette?) or the b-tension is in the wrong place (too close it’ll hit the cssette, to far it wont shift quickly).

If its the latter then either the mech or the hanger is bent, causes it not to index at one end of the cassette, fiddle enough and it’ll probably work fine in 8/9/10 but not in 1/2/3.

the bike is 10 months old….. has had a new chain after around 1000 miles …… covered around 1600 miles in total….. cassette not really worn….

think i might remove and lubricate gear cable?

Would adjusting the B screw help with this ? Would incorrect adjustment cause the issue?

Would adjusting the B screw help with this ? Would incorrect adjustment cause the issue?

If it was working OK a couple of weeks ago and you’ve not moved it, then unlikely IMO.

Cassette can be worn without being visible to the eye, but that’s evident as soon as you change the chain generally, not 600 miles later.

Use really thin oil to lube the cables, and the effect may not last too long as the lube attracts and then drags more dirt in. At least you’ll have identified the problem though.

Undid the cable to lube it and found it very restricted in the last section of outer…. Inner was frayed and a strand caught up inside….. Will get a new one and fingers crossed that May be it !

May be worth changing outer as well. In my experience for the sake of a few more pounds it should mean not having to do it all again in near future – the frayed cable may have damaged inner sheath on cable outer.