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Its a new bike with Ultegra 11sp and since day one about 50% of the time in bottom gear 34x32 it's made a gronking noise, regardless of state of lubrication of the chain. It looks like the chain line is very severe, and it sounds like it too. It seems to be load dependent.
I've never had 11sp road before, and my 11sp XT does not do this. But then again, the MTBs have repurposed triple cranks so they have had spacers adjusted to get a decent chain line.
The road bike looks as if the cranks are too far to the right but surely on a new bike everything should be specced to fit? I don't think there are any spacers on the cranks and it's a PF BB so no spacers to move, are there?
KMC chain?
Chain on the wrong way round?
Shimano chain, so I'd better check.
I'd start by checking rear mech alignment. But as it's a new bike I'd be talking to whomever you bought it from.
50% of the time in bottom gear 34×32
It looks like the chain line is very severe
Not just the guide pulley hitting the sprocket? Try a little more b-tension to see if that cures it.
I'd expect this in 50x32 but 34x32 should be quiet.
Is it definitely from the rear? We often see the chain rubbing the plastic guide on the inside plate of the front mech on bikes that aren't set up correctly/riders who haven't figured out the trim function on the front shifter.
Yeah it's not trim, I'm on top of that.
The writing on the chain plates was upside-down on the top run of chain. So I turned it upside down, and initially it felt better, drivetrain was definitely smoother overall. But the gronking was still there on the first big climb although I thought maybe a bit quieter. Then on the next big climb it seemed somehow further diminished. I guess it's possible I've worn something into a particular bias by running it upside down for hundreds of kms?
Might just change the chain and see.
I didn't look at pulley clearance actually.. but it didn't sound like that and I've experienced that before.
Not just the guide pulley hitting the sprocket? Try a little more b-tension to see if that cures it.
That was my first thought, had a look OP?
The writing on the chain plates was upside-down on the top run of chain.
Huh? The writing isn't the same way up on all of the links, some point up, some point down 🤣
As long as the writing faces outwards it is correct.
Oh I guess I didn't notice that!
Not just the guide pulley hitting the sprocket? Try a little more b-tension to see if that cures it.
Had this on mine... I changed from a 11-28t to a 11-30t cassette and it would occasionally catch until I wound the tension in by another turn.
I'm finding newest Shimano 11spd only works quietly with a Shimano chain. It appears the R8000 line uses a slightly narrower chain design and other chains e.g. KMC are slightly wider as a consequence and make a noise like you report. Had a new bike come with KMC and buying an Ultegra chain fixed it.
Now I've got to go down to the garage and check.
EDIT definitely a Shimano chain, but it's OEM so it's possible that it was assembled from bulk orders of parts that may nominally fit but not perfectly. I'll see if I can read any numbers on the chain.
I thought KMC made the Shimano chains, so are they making slightly different spec ones for Shimano?
Top pulley was about 2cm clear of the cassette - so I've wound the screw out, see if that helps. It probably won't.
The chain says CN-HG601 on it.
HG601 seems to be current 105, but it's not exactly clear. I have R8000 Ultegra mechs and cranks but guessing the cassette is a lower spec.
I'd be checking the gear hanger alignment and also to ensure that it is secured to the frame - quite often the little screws come loose and it waggles about.
I’m finding newest Shimano 11spd only works quietly with a Shimano chain. It appears the R8000 line uses a slightly narrower chain design and other chains e.g. KMC are slightly wider as a consequence and make a noise like you report.
I didn't get a "gronk" as such when running a KMC chain, but agree that a Shimano chain is noticeably quieter. This is on a mix of 5800 105 and R8000 Ultegra. I hadn't used Shimano chains since the mid 90s (back when they used to snap frequently)!
It's a chain line issue - it only does it in bottom gear, none of the others that you'd use in sensible usage. Doesn't even do it in 3rd largest sprocket and the big ring.
Doesn't seem to be front mech trim related because I can force the front mech to rub the chain and the noise is different. It is load related, but only a certain range - lighter load doesn't do it but neither does heaviest load - just moderate-heavy like taking my time on a steep hill. If I were to guess, the noise sounds like it's coming from the chainring as the chain meshes with it.
definitely a Shimano chain, but it’s OEM so it’s possible that it was assembled from bulk orders of parts that may nominally fit but not perfectly.
As a Madison rep once said to me, do you actually think Shimano run 2 different production lines or 2 different packaging lines?!?
If the chainline in small /big is wrong the cranks can't be spaced correctly or the cassette is fitted incorrectly, have you checked both?
As a Madison rep once said to me, do you actually think Shimano run 2 different production lines or 2 different packaging lines?!?
No, but if there's been a small change recently (as suggested above) it's possible Cube have old stock to clear, and it works enough to sell although not perfectly.
If the chainline in small /big is wrong the cranks can’t be spaced correctly or the cassette is fitted incorrectly, have you checked both?
No. No spacers required on this setup, are there? And I haven't had the cranks off - I guess there could be a spacer on the drive side I can't really see.