What is that grinding noise on my fixed gear?

[americancyclo]

I just changed the chain on my fixed gear over the weekend and on the first ride this morning, the drive train sounds loud and unhappy under load. Spinning along on the flats is fine, but when I stand up on the pedals, it gets loud and grindy.

Maybe I should have replaced the cog, too?
Chain tension too tight?

Topic

[dcv]

I’m going to guess chain’s too tight, but let’s check it out at coffee (out tomorrow though)

[vvill]

Put it in a stand and turn the pedals (carefully! being a fixed gear finger chopper and all). Watch the chain/cog interface.

If it’s not chain tension or imperfect chainring run out, it could be that the chain doesn’t match the slightly longer teeth of a fixed/SS cog. I had this issue once trying to use a Surly cog with a chain made for geared drivetrains. If you’re running 1/8th on both I doubt you’ll have that issue. I run 3/32″ though.

[DismalScientist]

Could be the bottom bracket or pedals as well.

My fixie was making a racket, but it turns out that my front hub had lost its grease. It’s not easy to determine where sounds are coming from when riding.

[americancyclo]

@vvill 146832 wrote:

Put it in a stand and turn the pedals (carefully! being a fixed gear finger chopper and all). Watch the chain/cog interface.

If it’s not chain tension or imperfect chainring run out, it could be that the chain doesn’t match the slightly longer teeth of a fixed/SS cog. I had this issue once trying to use a Surly cog with a chain made for geared drivetrains. If you’re running 1/8th on both I doubt you’ll have that issue. I run 3/32″ though.

It spun nicely and quietly in the stand.
Using a KMC 1.8″ chain, same model as the one that came off, and matches factory spec too.
Could the cog be super worn out? The chain was at 1.0

possible that the rear wheel is slightly out of alignment?

[huskerdont]

This has happened to me when I have changed an old chain on my fixie but not the cog/chain ring, so yeah, it’s a possibility. Alignment is also a possible cause. For some reason (for me at least) fixies seem to be noisier than shifties. The fixie is the only bike I use wet lube on b/c it seems to help it run quieter. (Caveat: the fixed is my rain bike so is run gunkier than the others.)

[vvill]

I’d take it back to whoever sold you this PoS.

Like Dismal said it could be something else… BB/cranks/pedals/hubs, etc. But if the noise only started with the new chain I’d guess it’s the cog or chainring. I don’t recall yet changing any of my FG/SS chains so I’m not sure what kind of wear one of those cogs really gets.

[Steve O]

@huskerdont 146181 wrote:

We really should have a Stump the Chumps thread. There are enough maintenance-related questions to do it.
The “Tom Magliozzi Memorial Stump the Chumps” thread.

ooo….ooo…
This is the perfect opportunity to initiate the “Stump the Chumps” thread.

Which chump will get the “grinding noise on the fixie” problem right?

[americancyclo]

@Steve O 146843 wrote:

ooo….ooo…
This is the perfect opportunity to initiate the “Stump the Chumps” thread.

Which chump will get the “grinding noise on the fixie” problem right?

set it up and I’ll get some audio/video

[Subby]

[ATTACH=CONFIG]12520[/ATTACH]

[OneEighth]

I’ve had that happen before when I changed the chain but not the cog or chainring. If you’ve got 1/4 to 1/2 inch play in the chain at the tightest point, then it is probably your cog and/or chainring.

[OneEighth]

One more thing, I found that Surly 17+ tooth cogs did not work well with my preferred chain. They tended to bind. Get Phils.

[ShawnoftheDread]

@OneEighth 146847 wrote:

One more thing, I found that Surly 17+ tooth cogs did not work well with my preferred chain. They tended to bind. Get Phils.

Smaller cog is the answer here.

[OmphalosSkeptic]

@ShawnoftheDread 146851 wrote:

Smaller cog is the answer here.

Seriously. What, do you skip leg day even on ride days?

[TwoWheelsDC]

Hard to say without actually hearing it. Some chains are louder than others (looking at you, KMC), and some chain/cog combinations are particularly loud (looking at you, KMC and Surly), especially if the chain is a bit too tight. My drivetrain (SRAM chain with an Origin8 cog*) seems to run quietest when the chain is looser than I’d prefer otherwise, which is something that isn’t apparent when just listening to it on the stand. So it may not be that your chain is objectively too tight, it could just be too tight for your current setup to run quietly. Of course, my definition of “quiet” may be different than others, as I’m running 1/8″ on an aluminum track bike…pretty much a recipe for noise.

*edit: 16t, of course.

[OneEighth]

@ShawnoftheDread 146851 wrote:

Smaller cog is the answer here.

Not when you are running big honking studded tires and riding in snow. But yes, otherwise the magic number is 16.

[Author]

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