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Sorry for the waffley post, just trying to convey enough detail in the hope that someone might be able to help. I've just been giving my On One Scandal some TLC and it's developed a noticeable low rumble from the drivetrain. I'm struggling to identify exactly where it's coming from but it appears to be from somewhere on the mech.
It's a Shimano SLX 1x11. The chain is relatively new, not worn, clean and lightly lubed. The gears have been indexed are are changing smoothly, there is no sideways chain rub in any gear. I don't have an alignment tool but visually the mech and hanger appear straight. It's not the BB, that's running smoothly. There is no rumble when the rear wheel is freewheeling. It happens when the cranks are rotated forward or backwards.
The chain is routed correctly in the mech and isn't rubbing on the cage anywhere. It eases if I disengage the clutch and seems to disappear if I put forward pressure on the bottom of the cage, so seems like it's something to do with chain/mech tension. I can feel the mech cage vibrating in time with the rumble and it feels worse in the vicinity of the bottom jockey wheel. I've had the jockey wheels out to clean them and they don't appear to be worn. Any ideas?
Same in all gears?
Yep. If anything slightly worse on the smaller cogs.
Grease the clutch barrel.
I'll give that a go, thanks
Either clutch or the freehub is starting to go - possibly due to grease loss are my suguesses.
Have you put narrow-wide jockey wheels on the mech? They make that noise if the narrow-wide isn’t aligned with the inner/outer chain plates
I also run an SLX mech (12 speed) with an 11 speed drivetrain. My cassette and chain now have 4710km on them. The only time I get rumbling is when the drivetrain is getting dirty towards the end of a ride, at the extremes of the cassette i.e. when the chainline is at its worst - but, crucially, and the chainring is worn. I run cheap Snail chainrings and replace them roughly every 2000km to mitigate against this. Your symptoms don't exactly match this but how old is the chainring?
I took out the SLX jockeys to clean them for the first time in 4400km a couple of weeks ago. I think simple bushing types like this are actually better than sealed bearings in this application.
I took out the SLX jockeys to clean them for the first time in 4400km a couple of weeks ago
That all looks a bit ninja-star,or is that what 12sp ones look like from new ?
No, getting near the end. The replacements (<£10) are already in the box ready to go on with a new cassette and chain fairly soon.
Is the chain on the right way and routed through the jockey wheels correctly?
Have you put narrow-wide jockey wheels on the mech? They make that noise if the narrow-wide isn’t aligned with the inner/outer chain plates
I've tried that T shirt, fortunately it's v easily resolved 🙂
Have you put narrow-wide jockey wheels on the mech?
No, bog standard SLX plastic jobbies.
Is the chain on the right way and routed through the jockey wheels correctly?
Yes! 😊
Thanks for all the suggestions. I've been a DIY slave today, so not had chance to take a proper look. I'll get some garage tinkering time tomorrow and will have a look at the clutch and freehub.
My money's on worn-out jockey wheels.
My money's on worn-out jockey wheels.
Nope, they're fine 🙂
it will be the lower jockey wheel bearing.
it will be the lower jockey wheel bearing.
The jockey wheels have bushings not bearings. They appeared fine when I cleaned them?
Hmmmmmm
Rumbling noise is normally a bearing. Hub?
Hub?
Possibly. I'm going to take a closer look today. However with the chain off, the wheel spins smoothly
Depending on the hub there could be a bearing that only turns when the cassettee turns.
Did you figure it out?