Drive train noise on T50

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Frank Costantini

Active Member
My T50 with 1x8 gearing, and pretty low mileage, makes an annoying noise when the chain is on largest or second largest cog, but not any other cog. I would describe it as a high-speed clicking sound. Shifting is great, derailleur pulley is well-aligned with cogs, and B adjustment looks good (although I didn’t measure it). Playing with the cable tension did not diminish the noise. I’ve had the bike about 2 years, but only noticed the sound recently, when I got new hearing aids- so it may have always been like this. I’m thinking of trying a (narrower) 9 speed chain, in case it’s due to something rubbing on the outside of the chain, although I don’t see anything rubbing.
Any other suggestions?
 
RojoRacing

RojoRacing

Donut Powered Wise-guy
have you removed or replaced the chain recently?

You really need to isolate where the noise is coming from for us to really narrow it down, there are dozen of things that can cause noise.
 
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Frank Costantini

Active Member
No, it’s been a while since I last removed the chain, since I only ride this bike occasionally. And unfortunately, I have no directional hearing (only one good ear), so I can’t tell if the noise is from the chainring or cassette/RD. I guess I can get someone else to listen and try to localize the noise.
 
B

Bill K

Guru
Just a shot in the dark, but I wonder if the chain line could be off, with the chainring being too far from the bottom bracket.
If there are spacers between the bottom bracket shell and bb, try removing them?
 
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Frank Costantini

Active Member
Thanks for the suggestion, I’ll look into that. I was thinking about the chain line as an issue, as a 1x8 setup means that the chainline Is going to vary, from large to small cog, more than it would with a 2x setup.
 
benphyr

benphyr

Guru-me-not
My 2c: before spending any more time on diagnosis - clean and lubricate the chain and see if that deals with the problem.

Then since you have just cleaned and lubricated everything you may be able to see evidence of where chain, derailleur, cogs, etc. are hitting something and clicking. Loose cassette locking nut can allow the cogs to move too but probably not your issue - wiggling the cogs left to right to check for play will check eliminate that possibility.
 
Rampa

Rampa

Guru
I would think it is the lower derailleur pulley. When it is pulled forward by the chain being on the larger cogs, you have less chain wrapping around it. The noise might just be jockey wheel teeth hitting the chain pins at a different angle.
 
benphyr

benphyr

Guru-me-not
Frank Costantini said:
Ok, thanks everyone - this gives me many possibilities to check out. Or, I could just remove my hearing aids :)
Click to expand...
Sounds like a universal solution. As for help so everyone feels like they have input and are a help. Remove the hearing aids so you don't have to hear all the suggestions AND so that you don't hear the problem anymore. Triple solution!
 
RojoRacing

RojoRacing

Donut Powered Wise-guy
are you sure the B adjustment is good? Because after so many miles when the chain start to wear in the chain will get just long enough to where the pully wheel start contacting the largest two cogs making a contacting noise with each tooth, just like you describe. Clean your drivetrain, give it some fresh lube and if the noise doesn't go away try turning your B adjuster screw in 2-3 turns and see if that solves it. The general rule is 10mm between the pully wheel and the largest cog but you can actually run it closer if you have a good understanding of how the stuff is designed to work and are good and maintaining the tolerances. You can also shift it into the largest cog and post a few pictures here so we can see how you have your tension setup.
 
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Frank Costantini

Active Member
I think its a square taper bottom bracket - this is a stock T50, not a frame-set that I built up.
Jason, Ill try playing with the B adjustment. The chain is waxed, so I don't add additional lube. I don't think it needs re-waxing, because it’s only on the two largest cogs that I hear the noise. I’m going to play with it this weekend and try out some of the ideas that have been posted.
 
F

Frank Costantini

Active Member
Here are two photos of the upper pulley with chain on largest cog C5BE6403-510A-4A0C-9561-9D110882F3A2.jpeg 028E42DE-F196-42E4-9D95-E8D496D9262B.jpeg

I now think the most likely cause is the chain rubbing on the inside of the chain guard, when on largest cogs. There is some wear inside chainguard visible here:
AB0A94E7-406F-4DBD-ADDF-F3DB081CD67C.jpeg

Here’s a front view showing chain very close to inside plate of chainguard:

45EDF822-B9C1-4C43-819D-62E5C10BB99C.jpeg

I can hold a piece of paper between chain and chainguard and the cranks still turn freely, so it’s not rubbing hard, but it still seems to touching sometimes, which could explain the noise. I could try a 9 speed chain, which is slightly narrower, or file down the inside of the chain guard?

Here’s a photo of the bottom bracket - I don’t think it is out of position. (??) :

2A914084-16A8-4CF7-9409-94AD2301E9B5.jpeg

Thanks for all your advice on this.

Frank
 
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Frank Costantini

Active Member
I also noticed that the spacing between the two plates of the chainguard is not even - in some places it’s >2 mm wider than in others, so one or both plates are likely bent. Best way to straighten them out? Or is it possible to add some kind of spacers to move the plates further apart?
 
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RojoRacing

RojoRacing

Donut Powered Wise-guy
get rid of those guide plates on the front chainring and get a narrow wide chainring to replace the one you have now. Unless you're riding some rough off road there should be little reason to need those plates with a quality chain and chainring setup.
 
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