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Discussion Starter · #1 ·
So i have this weird problem with the drivetrain on my brand new bike which drives me crazy.
Drivetrain is 2*11 SLX m7000 with XT m8000 rear derailleur and mt600 cranks.
When i use big chainring in the front and i downshift, after the chain moves to a bigger cog it starts vibrating and making some loud noises.
The worst thing that it vibrates so much that it starts rattling on the rear derailleur cage tab in between the jockey wheels. It happens mostly on the smaller cogs(1-5) when pedaling with a relatively high cadence and only when the clutch is ON.
here's some investigating i've done so far:
1) the chain installed correctly. No derailleur cage tab problem here. chain length and direction are correct
2) derailleur hanger is perfectly straight(checked with a tool)
3) limit screws and b-screw are set up properly.
4) no rubbing on the front derailleur
5) not a chainline issue. It is most noticeable in the middle of the cassette.
6) probably not a chordal action due to same reason as above.
7) no problems with the wheel, hub or the freehub body
8) problem disappears as soon as i stop pedaling
9) shifting is fast and accurate. not a cable tension problem.
10) if i enable the clutch and don't perform any shifting the problem does not appear.
11) goes away after the upshift. So if i downshift 2 gear and then upshift there's no vibration.
11) if a bit of pressure in applied against the clutch the vibration goes away.
12) tried different chain and it worked fine for the first couple of rides probably due to very thick grease in the new chain.
13) tried to lubricate the chain with some sticky and thick lube and it didn't help much.
14) Tried to adjust the clutch but in order to get rid of vibration i had to release the tension completely.
15) i've been to the LBS and they couldn't help.

 

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I can't see your youtube, but it seems like the system is resonating? Like the Tacoma Narrows Bridge ;-)

I can only suggest playing with stiffness and damping to move the resonant frequency
- ride without the clutch if you don't really need it
- add or take away chainlinks if it wouldn't be too tight / loose
- check tightness of cassette
- check tightness of hanger
- check tightness of axle
 

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Discussion Starter · #4 ·
Ride more ;) You have a new drivetrain, stuff is not yet loosened, so you get some extra chordal action. Nothing to see here :)
That's what i'm doing :)
I still hope to find some solution to at least get rid of the rattling.
The only thing that comes to my mind is to glue some rubber pad to the derailleur tab.
Thicker lube seemed to help a little. Is there any way that i could get the chain as greasy and sticky as the new one? Didn't notice any noises while the chain still had a factory grease.

I can't see your youtube, but it seems like the system is resonating? Like the Tacoma Narrows Bridge ;-)

I can only suggest playing with stiffness and damping to move the resonant frequency
- ride without the clutch if you don't really need it
- add or take away chainlinks if it wouldn't be too tight / loose
- check tightness of cassette
- check tightness of hanger
- check tightness of axle
Thanks for the suggestions :)
Riding without a clutch is not an option. It seems like the vibration is always there but the clutch amplifies it due to extra tension applied to the chain.
Chain length seems perfect. i measured it. The other chain i tried was 1-2 links shorter and it developed the same problem after a while.
The Cassette is tight. A bit of play in between the freewhub body and the hub but it's normal.
Hanger is tight.
Axle is tight.
This vibration also caused super annoying high pitch noise but i tracked it down to vibrating limiting screws on the derailleur and i fixed it by greasing the threads.
Also when i ride and it start vibrating it cause the brakes to rub.
I'm pretty sure i experience the same thing on my disc brake road bike equipped with Shimano 105 5800 but it's far less annoying. I actually thought that brake rubbing is the reason but it's the consequence apparently :)
 

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Are you adjusting the gears with or without the clutch turned on?

I don't recall what Shimano recommend but I usually adjust the gears with the clutch on. I do this because I noticed that going up the to bigger cogs the tension on the clutch prevents the derailleur to work the same way as to when the clutch is off.
 

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Discussion Starter · #6 ·
Are you adjusting the gears with or without the clutch turned on?

I don't recall what Shimano recommend but I usually adjust the gears with the clutch on. I do this because I noticed that going up the to bigger cogs the tension on the clutch prevents the derailleur to work the same way as to when the clutch is off.
Shimano recommends adjusting with the clutch OFF but i tried adjusting the cable tension with the clutch ON and it didn't make any difference.
As you can see on the video (0:15), after i downshift with the clutch ON it starts to rattle but after i pull the cage a bit it goes away without changing the position of the derailleur
 

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(...)
As you can see on the video (0:15), after i downshift with the clutch ON it starts to rattle but after i pull the cage a bit it goes away without changing the position of the derailleur
That's why I asked when I saw the video the first rime, when you down shift (go up to bigger cogs), the clutch somehow prevents the cage to freely align with the shifting pulley with the gear cog, making the chain rub, when you release the tension by pulling the cage it allowed the pulley and the cog to align.
I had that same problem and adjusting the gears with the clutch on made the rub alleviate.
I also went over every single bolt on the derailleur and hanger to make sure they were properly tighten.
I think it was already mentioned, but make sure your hanger isn't bent.
 

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You could take it to a bike shop and see what they say. All the shops I know would put it on a stand, do a quick evaluation discussing it with you as they do it, and tell you what they think. The eval is free. The explanation is free. A quick adjustment might be free. If a full adjustment or correcting a significant issue is required, they'll give you an estimate. These shops want you to have the best cycling experience possible and want you to come back, even if you bought a mail-order bike.
 

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I have watched your video and I can't hear much of a difference, and I certainly can't see it. You don't let it run long enough for me to ID much.

That said, I recently had an issue with my M9100 derailleur where it was vibrating and draggy and weird. I had to re-adjust everything because the cable slipped in the pinch bolt. My fault...I guess I didn't tighten it enough. After I adjusted everything, I started getting the weird draggy vibration thing I couldn't track down. It sorta had a similar feel to the b-screw being out of adjustment, so the upper jockey pulley pressed up into the cogs. Except it wasn't doing that. I removed the rear wheel and reinstalled it and got it to go away. I still don't know what caused it, but that was quite some time ago and everything has been fine since.

I also adjust everything with the clutch on. I have since clutches came out. I ride with the clutch on, so I don't see why I wouldn't do it that way.
 

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Discussion Starter · #10 ·
Now i'm almost certain that it's the lower jockey wheel that cause this vibration. The shifts are smooth and the upper jockey wheel is perfectly aligned with the cog but it seems like the cage is not, which makes the lower jockey wheel to engage with the chain under a slight angle. When i pull the cage or i hit the bump while riding the cage get's in the correct position.
The lower jockey wheel is positioned with a slight tilt and when i first saw it i thought that the cage is twisted but it seems like it's designed this way:

i believe the idea is to compensate extreme chainlines.
 

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Discussion Starter · #13 ·
AgoOne Pivot
The video looked like normal drivetrain operation. It makes a little bit of noise, but they all do
I admit it doesn't sound convincing on the video, I'll try to make another one. It's a very noticable grinding/vibration very similar to b-screw not adjusted correctly like someone mentioned. Only after downshift.

AgoOneTrustMan
Hello Pau.

I could be wrong, but next time you have this vibrating thing while you ride,
try to screw in the B-screw 1 or 2 full rounds.

I'm not saying you adjusted it wrong, but just to try it.
Hello. Thanks for your reply :)
I did try it and it make zero difference so as the cable tension didn't. I will try a different derailleur and see if changes anything. Until then i downshift two gears down and then one gear up :)
 

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Discussion Starter · #14 ·
BTW i also tried a different cassette and chainring in 1x setup: 11-46 slx cassette with slx narrow wide chainring and the problem was still there.
Also tried lubing pivot points of the derailleur and greasing the clutch.

Maybe that's just how these derailleurs work? Can anyone confirm?

The most annoying thing is that i can actually fix it by pulling the cage 1-2mm
 

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Hi,

I know post is old, but i just found it, and it's exactly the same issue i have on 'new' used bike and brainstorming for days what could be the cause. So i'm wondering did you ever found a solution?
My previous bike was also with M8000, and it didn't have such issue, so i know it's not supposed to work like that.
 

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Discussion Starter · #16 ·
Hi,

I know post is old, but i just found it, and it's exactly the same issue i have on 'new' used bike and brainstorming for days what could be the cause. So i'm wondering did you ever found a solution?
My previous bike was also with M8000, and it didn't have such issue, so i know it's not supposed to work like that.
Hi, i ended up swapping for the short cage derailleur which solved the problem for me.
 

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Discussion Starter · #20 ·
From my experience buying a new derailleur is not worth it. My old derailleur was only making noises on high speeds in high gears which were achievable only on the tarmac. I never noticed it on the trails.
You can also glue a piece of rubber to the derailleur cage and that will eliminate the noise
 
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