I just fitted a new SLX 12 rear mech and shifter to an otherwise new NX groupset. Shifting is good, not great but good. I had to turn in the B screw all the way to get near the marker on the back of the rear mech. The marker is for a 51t SLX cassette but of course my NX cassette is a 50t.
I still can't get perfectly aligned, the photo makes it look better than it is due to parallax.
It would seem that the only way to get closer is to shorten the chain (which was optimised for NX shifter and mech with the plastic guide).
So, is that good enough and the remaining margin due to the smaller 50t ring ? (I can't get my hear round that one).
Is shortening the chain going to improve things or is the ultimate shifting quality limited by my use of a non-Shimano 12 speed cassette?
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I’d suggest setting the chain length in accordance with Shimano’s instructions so it is correct for the mech. That may well solve your issue.
I have an SLX mech with GX Eagle cassette and shifter on 2 bikes and it all adjusts correctly with the line on the cage lining up fine. Shifting is great though arguably it may miss the final 1% due to the different ramp profiles on the cassettes. That’s nothing when covered in mud or riding off road!
Thanks a lot Ginkster. Is your GX Eagle cassette 50t? Or is that irrelevant?
Why on earth would you put a Shimano mech onto a SRAM cassette?
Why on earth not?
I bought the NX groupset for £200, then bought the SLX mech and shifter for £67 off Merlin and sold the NX shifter and mech for £75 net. I prefer the SLX shifter and the NX rear mech is prone to early wear.
I have been combining SRAM cassettes and Shimano rear mech for a long time in 11 speed, best of both worlds IME.
Plus, my freewheel is HG anyway.
jhinwxm
Free Member
Why on earth would you put a Shimano mech onto a SRAM cassette?
Sounds like a potentially great combination of mech and everlasting cassette to me
Thanks a lot Ginkster. Is your GX Eagle cassette 50t? Or is that irrelevant?
Mine are 50T too. 50 or 51 is a tiny difference to the diameter of the cassette so will have almost zero impact to the set up.
Why on earth would you put a Shimano mech onto a SRAM cassette?
Why not? I went that route as GX Eagle mechs were in very short supply a year or so ago and ludicrously priced if you could even find one. An SLX mech was readily available, half the price and just as well built. The fact it works perfectly means it is a very valid solution. The shifter and chain are probably more important than the choice of mech.
I suspect this is all down to chain length - the new Shimano 12 speed mechs don't like a short chain, and that applies to the old "big to big then add two links" method. You'll need to measure your chain in accordance with Shimano's instructions and I bet it'll be a link longer.
It looks like your B screw needs to be wound in more too.
NX rear mechs are made of some kind of soft cheese, seen them wear out and become so floppy they need replacing within the time 1 chain is worn, GX which looks identical is much better. Deore/SLX/XT are all similar to GX in longevity, i.e. fine.
If you can't get the B axle adjustment to get the RD to the right place, you need more or less chain links. Shimano tech docs has all the info you need.
Cheers. I'll take the chain off tomorrow and check compliance with Shimano specs for length. I suspect it is a little too long as it doesn't look too short when in the 50t but will report back.
So I took the chain off and it's bang on the Shimano 12 recommendation for a hardtail.
But my cassette is 50 rather than 51 (but that's probably not relevant), but I can almost put the chain on the next tooth, but not quite, probably 80% of the way (does that make any sense).
That still doesn't explain why I can't quite get the b screw gap right on.
Is it possible that the mech itself is not at the right angle because of how it is mounted on the mech hanger? Should there be any leeway there?
If not I might just leave it. The shifting is decent and might improve with mileage (it is still practically on 0 miles and the transport grease is still on the chain).