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View Full Version : What is that grinding noise on my fixed gear?



americancyclo
10-04-2016, 07:43 AM
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?

dcv
10-04-2016, 08:13 AM
I'm going to guess chain's too tight, but let's check it out at coffee (out tomorrow though)

vvill
10-04-2016, 08:27 AM
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
10-04-2016, 08:40 AM
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
10-04-2016, 08:41 AM
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
10-04-2016, 08:56 AM
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
10-04-2016, 09:10 AM
I'd take it back to whoever sold you this PoS. :D

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
10-04-2016, 09:20 AM
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
10-04-2016, 09:21 AM
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
10-04-2016, 09:23 AM
12520

OneEighth
10-04-2016, 09:33 AM
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
10-04-2016, 09:41 AM
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
10-04-2016, 09:58 AM
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
10-04-2016, 10:02 AM
Smaller cog is the answer here.

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

TwoWheelsDC
10-04-2016, 10:15 AM
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
10-04-2016, 10:25 AM
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.

ShawnoftheDread
10-04-2016, 10:30 AM
Not when you are running big honking studded tires and riding in snow. But yes, otherwise the magic number is 16.

Some people don't go out in snow because it messes with their chi or something.

EasyRider
10-04-2016, 10:38 AM
but when I stand up on the pedals, it gets loud and grindy.

I agree with others about chain tension. My guess is that the frame is flexing a tiny bit when you stand on the pedals, increasing the chain tension. To account for it, I'd just need to move the rear wheel forward in the dropout a tiny bit, taking care to make sure it is centered. Did you remove the wheel when you replaced the chain? I'd also check to see if the chainring bolts needed a quarter turn. Your rear cog doesn't look worn out to me.

Back when my commute was shorter and flatter, as my fixed gear's chain would wear, I'd bump the wheel back once or twice by a fraction of an inch to maintain chain tension, before finally replacing it. Sounds like you maybe just need to do the opposite, since it's a new chain.

americancyclo
10-04-2016, 10:51 AM
I agree with others about chain tension. My guess is that the frame is flexing a tiny bit when you stand on the pedals, increasing the chain tension. To account for it, I'd just need to move the rear wheel forward in the dropout a tiny bit, taking care to make sure it is centered. Did you remove the wheel when you replaced the chain? I'd also check to see if the chainring bolts needed a quarter turn. Your rear cog doesn't look worn out to me.

Back when my commute was shorter and flatter, as my fixed gear's chain would wear, I'd bump the wheel back once or twice by a fraction of an inch to maintain chain tension, before finally replacing it. Sounds like you maybe just need to do the opposite, since it's a new chain.

I had to re position the wheel when I put the new chain on. The old one was stretched to at least 1.0 on the chain checker. Bike was quiet before the new chain and nothing else changed, so it's gotta be the tension, cog, or chain ring. I made sure to tighten the chain ring bolts before i put on the new chain.

EasyRider
10-04-2016, 10:59 AM
This got me thinking about chain wear and fixed gear. It's been a few years since I rode a fixed gear, but as I said, my memory is that I would periodically bump the wheel back to maintain chain tension. But thinking about it, my understanding of chain wear/stretch is too vague to know if chain wear would actually result in less chain tension on a fixed gear bike that could remedied by moving the wheel back. In other words, perhaps I'm full of it?

Still, it sounds like your chain is just a hair too tight.

americancyclo
10-04-2016, 12:50 PM
sounds like this:

https://youtu.be/HzCVEhb1J4k

ShawnoftheDread
10-04-2016, 12:58 PM
Note to self: negotiate cost of neglected maintenance when purchasing bikes from Subby.


Sent from my iPhone using Tapatalk

huskerdont
10-04-2016, 01:08 PM
Mostly I hear wind noise (I have been to too many punk and metal shows though), but that chain looks bouncy, not too tight. So this chump doubles down on the cog.

bentbike33
10-04-2016, 02:59 PM
Mostly I hear wind noise (I have been to too many punk and metal shows though), but that chain looks bouncy, not too tight. So this chump doubles down on the cog.

Speaking as a chump who rides only bikes with shifters, why wouldn't you replace the cog and chainring on a SS/fixie when you replaced the chain, especially if the chain has measurably stretched? You might be able to get away with a chain-only change if you are derailleured up because the chain wears over multiple cogs and chainrings, which is obviously not the case on SS/fixie set-ups. A new chain on a cassette that should have been changed makes some ugly noises too.

americancyclo
10-04-2016, 03:03 PM
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.

Does that mean you change all three at once?

EasyRider
10-04-2016, 03:08 PM
I would think that if it's a worn cog not meshing properly with a new chain, it'd be noisy all the time, and not just when you are out of the saddle, but I second huskerdont's advice. Even if the free solutions (easing up on the chain tension, checking wheel alignment) solve the problem, buy a new cog. A brand-new cog is a delight to hold.

TwoWheelsDC
10-04-2016, 03:36 PM
Speaking as a chump who rides only bikes with shifters, why wouldn't you replace the cog and chainring on a SS/fixie when you replaced the chain, especially if the chain has measurably stretched? You might be able to get away with a chain-only change if you are derailleured up because the chain wears over multiple cogs and chainrings, which is obviously not the case on SS/fixie set-ups. A new chain on a cassette that should have been changed makes some ugly noises too.

Fixed gear drivetrains are generally pretty robust (no shifting ramps and what not, and 1/8" is pretty hefty) so I can't imagine needing a sprocket change for every chain change. Since no shifting is involved, you can generally get longer useful life out of them even if they are worn, assuming you can deal with increased noise.

honestmachinery
10-04-2016, 08:43 PM
Fixed gear drivetrains are generally pretty robust (no shifting ramps and what not, and 1/8" is pretty hefty) so I can't imagine needing a sprocket change for every chain change. Since no shifting is involved, you can generally get longer useful life out of them even if they are worn, assuming you can deal with increased noise.
1/8 inch cogs and chainwheels should last a long time with timely chain replacement. I changed my chain before it was indicated by chain length, and it was definitely noisier. As long as the chain isn't binding at any point through a complete revolution, or hanging on the teeth, I wouldn't worry.

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americancyclo
10-05-2016, 08:56 AM
Going to try a new cog, and considering a new chainring as well. Will update when i get it installed.

huskerdont
10-05-2016, 09:31 AM
Speaking as a chump who rides only bikes with shifters, why wouldn't you replace the cog and chainring on a SS/fixie when you replaced the chain, especially if the chain has measurably stretched? You might be able to get away with a chain-only change if you are derailleured up because the chain wears over multiple cogs and chainrings, which is obviously not the case on SS/fixie set-ups. A new chain on a cassette that should have been changed makes some ugly noises too.

Somehow missed this. The site doesn't always show new posts in bold for me, but I tend to trust it like it does.

So, yeah, you might well change them all at once, if that's the way you do things, and many people do. I tend to try the chain first to see if I can get away with it, then move to the cog, then go to the chain ring as a last resort. Cheap maybe, but if you replace your chain in time, before it wears the other parts down, it works, just as it might work on a bike with gears.

I just discovered that my 9-speed road bike suddenly has chain wear that shows on the wear indicator at 0.5 but not at 0.75, so I'm going to get a new chain first and see what happens before I change the cassette. I may end up needing a cassette too, and in the past I probably would have replaced both at once, but since I have the wear indicator, I thought I'd give it a try. I think it's just a way of doing things and isn't either right or wrong. I don't change chain rings on a shifty bike unless I've hurt myself at least once when the chain comes off.