Source
r/bikewrench•
CallMeBryce

Tearing my hair out with this grinding noise!

Managed develop a horrible grinding noise in my drive chain slightly before snapping my fixed gear chain last week whilst commuting.

Swapped it over with a new one and it's been nothing but chainsaw noises when pushing on pedals (even worse uphill). So far I've swapped the bottom bracket, tightened crank arms and crank bolts, finally swapped the chain. Yet the noise continues....

Being a poor nursing student, I can't afford to take it into a shop. Is the slight "sharking" on the cog to cause this sounds?.

Or something more serious? Whats the next step to sort this?

Thanks for any help!

Posted May 19, 2014, 6:43 PM UTC

512
ahtopahtel•

Hey - if possible record a short video with sound - sometimes it's easier to recognize a problem by listening to the type of noise it creates.

3
CallMeBryceOP•

Thanks for the reply, I did try but it's impossible to do without pedalling it weighted, and then it's so low quality sound that you can't work out much!

1
spencerjustin•

if it only happens weighted then i would think that it is in the BB.... but you have changed that out?

is your chain too tight? yet that would still make a noise in the stand un-weighted...

puzzling.. have a buddy record you while he rides next to you, lol

3
BicyclingBabe•

I have heard noises like this when the chain is too tight .. Chreck this!

3
CallMeBryceOP•

Weighted wasn't the best phrase to use. Grinds when pedalled when in saddle at any speed/ force and gets much worse when standing for hills. Swapped the pedals to make sure it wasn't that. Must be wheel bearings.....

1
spencerjustin•

so it does it when you are not pedaling also?

1
CapnScrunch•

Is the front chainring lined up with the rear cog perfectly? If not, the sound you're hearing might be from the chain adjusting as it hits the teeth (both front & back) at an angle.

2
El_Glenn•

Do both wheels spin freely with the chain off? Possible wheel bearing?

1
CallMeBryceOP•

Both wheels spin freely. It's not the front as I've just popped that on another bike (just to make sure). Might be the rear hub? The back on spins fine with the chain off, although it has seen 3 years hard use.

2
Deathbike•

The back on spins fine with the chain off, although it has seen 3 years hard use.

Hopefully you've figured it out by now, but it seems reasonable to repack and/or replace your hub bearings. On a fixed gear they take a lot more abuse than with a freewheel.

1
Zekohl•

Could you take a picture from above or behind showing the clearance of the cog, if possible once with a chain on and once without?

If you say this happens even if you take the wheel into another bike it will probably be something with the wheel, not the BB or something similar.

My guess is that the chain itself rubs on a part nearby, either the hub or spokes or something, but thats just a guess.

1
jeseely•

Chain rubbing the front derailleur? Your crank/BB will flex a bit more when weighted, could it be the chain being pushed into the derailleur cage?

0