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OK, so you know when you offer to help, thinking it's pretty straightforward and yikes, big fail.
Nice Whyte bike with Sram GX 12 speed. Trouble with smooth shifting. His chain and cassette was reasonably worn so he bought a new pair and asked me to help out. Chainring looks good.
So I
- replaced the gear cable (feels nice and smooth in the outer)
- correct chain length
- fitted cassette
- checked hanger with alignment tool - spot on
- checked mech to be firmly bolted (jockey wheel a little free play - not sure if this is normal)
- adjusted higher gear limit screw
- left B-screw at factory setting
- attached gear cable, correctly routed
- ran up the gears and set lower limit screw
So it shifts up quite nicely, but ragged going down.
On the 2nd biggest gear (52T cassette), it seems to be trying to ride onto the 52T gear.
It's a bit clicky on a couple of mid gears.
Just doesn't feel confident reliable shifting.
Have played with B-screw (don't have the tool) to try and get the 15mm gap with 30% sag. Measured with ruler, and then played half a turn at a time up and down.
Just can't get nice shifting.
What am I doing wrong?
Wonder if the mech hanger is misaligned (looks good on smallest cogs, but increasingly out of line from mid upwards)? But an expensive trial to see!
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Help!
Wonder if the mech hanger is misaligned
You said you checked it with the tool - how could it be misaligned?
Did you check in both axes?
Whoops, meant to say 'wonder if the rear derailleur cage is bent'?
With the lower limit I think sram say to set it without the chain off and have the jockey wheel teeth on the outer edge of the teeth of the smallest cog. Have you done it this way?
Sam thanks, new to me (I'm not a sram user) but will have a go
Did you change the outer or at least trim the ends? Is the cable routed correctly through the mech?
I had a gear alignment issue with my 12 speed GX that seemed to not be solved by lots of twiddling with the cable tension and limit screws. I was recommended to buy the specific alignment tool but instead used this guide (as I'm tight and impatient).
Works a treat now. I didn't bother with the suspension sag as my bike doesn't have a pivot back there so thought it wouldn't matter and so it seems after riding it.
Is the rear axle tight?
Is there play in the rear wheel or cassette?
Is there play in the bottom bracket?
Is there play in the chain ring?
Is the chain fitted the right way round?
I'd change the gear cable (inner and outer) and jockey wheels when changing both the cassette and chain.
Great, thanks all. Will work thru all the suggestions and repirt back
Although you left the B-Limit screw, have you checked it at sag as required?
Check the derailleur parallelogram as well, I had a similar issue (and similar frustrations!) and it turned out to be play in the bushings. A new one fixed the issue.
OK, thanks for all the advice, have worked through it all. Still getting some inconsistencies on the shifting or clicking when in gear.
I 'think' it looks like the cassette is weaving slightly side to side. I've removed the cassette and very carefully refitted, nos sign of stripped threads, slotted into place smoothly, torqued to 40nM and still it seems to be weaving side to side, no loose play at all.
And, removing the rear brake, and the rear wheel feels as tho there's a little friction. He had the wheel bearings replaced recently.
So possibly a freehub issue? Thoughts?
OK, don't know if this is making shifting bad, but the freehub bearings are mullered, bits of metal fell out!
So the wheelset 27.5, RaceFace AR30 boost on a Whyte t-130. Will this fit
https://www.wiggle.co.uk/nukeproof-neutron-v1-freehub-body-sram-xd
Sorry, new to Sram!
‘wonder if the rear derailleur cage is bent’?
I'd say this ^^^^^ from that pic, it could just be the angle the pic was taken from but the cage looks slightly twisted to me
So a quick update. Have worked thru advice above, still rubbish shifting.
Was convinced the cassette was 'weaving' side to side slightly, altho no loose play at all.
Took the freehub off and looks like the inner (tiny) bearing cage has self-combusted, shards of metal and a mess. Also, only 2 of the pawls had springs - wonder where the others have gone.
Its a FORMULA FH-568H freehub, can't find on online. Popped into a Whyte delearship and they they'll hopefully ask Whyte to track one down. Really hope that this solves it!
Final update I hope...the old Formula freehub had somehow chewed its bearings. New 9ne fitted, looking good