I’ve just swapped everything from one frame to another.
Everything was working fine previously but now my gears are to cack. I’m using Shimano SLX 12 speed.
The only thing that has changed between the two builds is I’ve fitted new cable & outer, due to the difference in length caused by different routing.
The problem I’m having is the derailleur doesn’t return once I’ve pulled the trigger shifter; it used to be instant but it now lazily moves across & no amount of tweaking of cable tension or any other adjustment seems to make a difference.
Started from scratch a few times, I’ve removed the cable, lubed it, lubed the cable outer (internally obviously), slightly altered the outer routing to give a straighter route, but nothings changed it.
The derailleur moves freely without cables attached & the trigger shifter feels fine & moves the cable properly. However, I’ve noticed that when everything is attached the thumb shifter (for changing down the gears/up the block) is very stiff, as though there’s not enough leverage or waaay to much friction.
The cable is properly attached at the derailleur to provide the correct leverage.
I think I’m gonna buy some different cable & outer. Anybody got any ideas before do this? Also what is the slippiest cable & outer available?
Sounds like the cable isn't installed properly in the shifter. I'd check there first. Then check the mech cable route on the mech itself.
Is the inner correctly routed at the rear mech?
Could also be your clutch. Try shifting without it on to see if that makes a difference. If it does, you will need to at least clean it, probably replace it.
Have you readjusted the B-screw for the new frame?
Has the new frame meant that the derailleur is now at an extreme when in the largest sprocket?
I've recently put SRAM GX1 11 speed on two bikes with the Hope Hub Boost conversion kit. It means the cassette is inward of what is optimal and the mech is a hair off fully extended. It took a lot of faffing with cable tension and b-tension to get it to work. At this extreme it is incredibly sensitive to b-tension adjustment. Literally 1/8 of a turn too far and it will not drop. Back it off and it is fine.
12 speed is a level higher again in terms of how sensitive it seems to be to adjustment, so it might be a case of trial and error, perhaps?
Could be a restriction in the cut ends of the new outer? Try opening them up with a spike? Cutting outers can crush them
What cable ? SP41 is best.
Disconnect derailleur. Pull cable tight between thumb and forefinger. Operate shifter up and down while maintaining tension on cable. You will be able to establish if it's a cable/outer issue or if they are ok. It should feel crisp and snappy up and down
I suspect you have a slightly kinked outer or a inner that has opened up or lust a wire. Or possibly a dragging cable route
Is it moving quickly without the chain and slow with it? If so b limit
B tension is set correctly for new frame (checked, re-checked & checked again).
You can only thread the cable through the shifter correctly, as it only aligns the holes in one position (highest gear).
The derailleur does not sit at a funky angle when on the largest sprocket & the clutch works properly.
The outer ends are cleanly cut & open; I always use a small pick then line the inner before fitting new cables & outers - they last a lot longer. That said, the cable was a little “resistant” to being pushed through the outer, which I initially put down to the loop you have to create for when the suspension compresses. As Spooky alludes to, It actually feels like the cable is slightly too big for this inner (or outer too narrow for the inner). They are both new but unbranded dug out from the bottom of a spares box.
Because everything worked perfectly prior to swapping frames (and they have few miles wear & tear), & because the only thing changed is the cable & outer it has to be this.
Ive bought some new Jagwire cables & outer today so I’ll have another tinker tomorrow.
When I was a wrench we used 1.1mm all the time, it just worked better.
I remember advice that you aren't meant to lube cables (even tho some outer came pre lubed).
A kink or poor routing would be my other suspicions.
Sounds like you've got the cause but how did you adjust the b-tension screw? Hopefully had the suspension set in sagged position - that makes a world of difference as well...
Jagwire and Shimano are my go to. I fitted some new PTFE lined shift cables and inners to a 105 10 speed CX bike. Worked fine for 6 months then shifts started being lazy. Changed to SP41 and it was perfect again.
1.1mm slick stainless inners EVERY time with SP41 OUTER
All sorted.
i think the culprit was the black (supposedly) Teflon coated inner - the stainless inner moved much smoother through the unknown/unbranded outer, but even better using the Jagwire outer.
Its weird, the black cable looks & feels thinner than the stainless cable, but it obviously drags or creates friction somehow 🤷♂️
I used the Shimano SLX derailleur dealer instructions to set the b screw. I was pretty much spot on. The chain could do with being maybe a link longer but it’s virtually perfect. Whoever mentioned it above is right, the Shimano 12 speed stuff is more fussy to set up & easier to get wrong than the predecessors.
Anyway, all done - thanks all 👍🏻
