When my rear mech is set tight i.e. when I move to big on the front crank the rear mech doesn’t move enough when I hit the trigger.

it gets harder to press the 9 speed lever and it doesn’t move as much with each click until I drop to the middle front cog then it moves fine!

any ideas?!

its SRAM x5 rear and sram x9 trigger

Diagnose…. replacing cable and outers would be relatively cheap, I’d start there.

Any of the following:

Worn/dirty cables? Replace inners and outers.

Bent mech hanger?

Chain too short?

Worn rear mech?

Sounds like the cabling is worth a try.

does anyone know what size I need?

thanks for your help

Any of the following:

Worn/dirty cables? Replace inners and outers.

Bent mech hanger?

Chain too short?

Worn rear mech?

wot he said

gear cables are all the same size. it’ll be longer than what you need so you’ll need to trim it once its fitted and the gears are working again

Fail to see why it would be cables if it shifts fine in the middle ring.

OP what do you mean by ‘set tight’?

Does it shift fine across the whole cassette if in the middle ring?

Shifts perfectly all gears on middle ring.

If i loosen the b tension i think it is on the rear mech then things improve however then the chain is loose ish

OK in that case I don’t think it’s the cables.

The B tension screw is only for adjusting the distance between the upper jockey wheel and the cassette. It doesn’t affect the chain tension.

Shift to the largest rear cog, then adjust the B tension so the upper jockey wheel is as close as possible to the cog, but not interfering or rubbing.

If that doesn’t fix, and your chain is the right length then maybe it’s bent.

It’s worth learning about this stuff so check out Park Tool’s excellent guide.

in that case I’m going to try bidding on a long mech on ebay.

don’t want to spend much as trying to save for a new bike.

MTBing is expensive lol
cheers for you help