Shimano GRX chain issue

[Dakrisht]

12-speed chains on 11-speed drivetrains.

Now this has me thinking that there *must* be an advantage to an 11-speed chain like the Dura Ace chain on an 11-speed drivetrain haha.

Let's get those comments going.

[pdlpsher1]

I have one bike needing new chains. I ordered two M9100 chains to see if the claims are true.

[Discodan]

I don't think there 'must' be an advantage of running 11s chain on 11s drivetrain, as the 12s is a later generation and didn't exist when the 11s drivetrain was released. It just seems to be better all round

FWIW I've been running 12s XT chain on my 8070 and it's all upside for me

[Dakrisht]

I don't think there 'must' be an advantage of running 11s chain on 11s drivetrain, as the 12s is a later generation and didn't exist when the 11s drivetrain was released. It just seems to be better all round

This is a good point. Later (newer) generation chain technology with obvious improvements.

I haven't had enough road time to feel a difference in shift performance - but from the repair stand, shifting between front chain rings is a touch smoother and the noise difference - night and day.

The drivetrain is almost SILENT at this point. I'm a bit shocked at the noise reduction. It's amazing.

I was thinking of getting the CN-HG901 Dura Ace chain for my Ultegra 11s, but might as well just get another XT CN-M8100 / XTR CN-M9100 12s chain instead.

[Oggyyy]

@Dakrisht

Were you running a 12 speed shimano chain with a GRX 11 speed chainring? When I've tried this the chain wont work with the chainring....

[robbosmans]

You can’t run shimano 12s chains on 11s narrow wide chainrings

[Oggyyy]

You can’t run shimano 12s chains on 11s narrow wide chainrings

Would a sram 12 speed chain work?

[robbosmans]

Yes

[jromano89]

The shifting performance of my GRX 1by is also a bit fiddly.

I've replaced the cable and triple-checked the derailleur alignment, but the performance is still subpar. Based of this thread, I'll check the M7000 cassette for manufacturing defects. Any other ideas are welcome too.

[robbosmans]

It sounds like the classic bend derailleur hanger, but you checked that so my guess would be the shift cable not operating smoothly, I would install new inners and outers

[TheDoctor]

It may sound silly but as an easy check, are all outer cable ends seated properly in their ferrules and the derailleur, and is the inner cable properly fixed at the derailleur end? If that cable's bolt is a bit loose and the cable slips under tension even by a bit you'll not be able to get the shifting right. Been there myself...

[ghostinthemachine]

I've replaced the cable and triple-checked the derailleur alignment, but the performance is still subpar.

is the cable clamped in the right place, and how did you check the hanger?

[jromano89]

is the cable clamped in the right place, and how did you check the hanger?

I just did a complete tear down and rebuild, while following the Shimano dealer manuals for each step, and have some updates. Shifting is considerably better now. The main culprits I believe were a slightly bent b-axle unit, and a missing 1.85mm spacer behind the cassette. I still think there's room for improvement by using a YBN chain instead of the 105 chain, but I'm happy this is finally sorted. Took forever to narrow down.

[PoorCyclist]

Mine was also missing the 1.85 spacer on a GRX 1x, it was pretty bad. Chain falls off when backpedal 1/4 turn.
It was like a new bike after installing it. However still have a touchy problem of cogs clicking very sensitive with tension.

Some shops don't know because most gravel bike use a 11s road bike hub but a MTB cassette that is a 10 speed spacing, strangely enough without the spacer it could still be (over)tightened down. You just get a bad chain line in the largest cogs in the back.

[jromano89]

Mine was also missing the 1.85 spacer on a GRX 1x, it was pretty bad. Chain falls off when backpedal 1/4 turn.
It was like a new bike after installing it. However still have a touchy problem of cogs clicking very sensitive with tension.

Yeah, I only bent the b-axle about 3mm (measured at the rim), so the GRX system appears more sensitive to adjustment than my previous Apex 1 drivetrain. I imagine some wear on the cassette will also smooth things out.