fixed gear drivetrain noise?

hi there, i have a question about a noise/grinding sensation coming
from the drive train on my fixie. it's a sort of
crunchy/grinding/sand-in-the-works sort of noise, and i can feel it a
bit through my pedals (spd clones)--in particular, on the drive side.
it seems to be most noticeable when powering uphill, and it might be my
imagination, but seems to be concentrated in the power part of the
stroke, i.e. from top dead center to bottom dead center.

a couple observations:
1) wiping the chain off doesn't seem to make a difference, and the
drivetrain doesn't seem to be that dirty anyway (i don't ride through
rain, off road, etc..)
2) had a new sealed cartridge bottom bracket put in about a year ago or
so by my lbs.
3) it's an old fuji road bike conversion, if that makes any difference.
4) the bike has never been totally whisper quiet--there's always been
an off and on chain-meshing-chainring sound, if that's indicative of
anything off in the drivetrain.

any theories/diagnoses--chainline off? chain too tight? crapped out bb?
overactive imagination?
thanks!
~vincent.

autopi wrote:

hi there, i have a question about a noise/grinding sensation coming
from the drive train on my fixie. it's a sort of
crunchy/grinding/sand-in-the-works sort of noise, and i can feel it a
bit through my pedals (spd clones)--in particular, on the drive side.
it seems to be most noticeable when powering uphill, and it might be my
imagination, but seems to be concentrated in the power part of the
stroke, i.e. from top dead center to bottom dead center.

a couple observations:
1) wiping the chain off doesn't seem to make a difference, and the
drivetrain doesn't seem to be that dirty anyway (i don't ride through
rain, off road, etc..)
2) had a new sealed cartridge bottom bracket put in about a year ago or
so by my lbs.
3) it's an old fuji road bike conversion, if that makes any difference.
4) the bike has never been totally whisper quiet--there's always been
an off and on chain-meshing-chainring sound, if that's indicative of
anything off in the drivetrain.

any theories/diagnoses--chainline off? chain too tight? crapped out bb?
overactive imagination?

Wild guesses... bearings in your pedal (most likely) or bearings in the
back wheel (less likely) are kaput.

--
Dave
dvt at psu dot edu

Tight chain.

autopi wrote:
hi there, i have a question about a noise/grinding sensation coming
from the drive train on my fixie. it's a sort of
crunchy/grinding/sand-in-the-works sort of noise, and i can feel it a
bit through my pedals (spd clones)--in particular, on the drive side.
it seems to be most noticeable when powering uphill, and it might be my
imagination, but seems to be concentrated in the power part of the
stroke, i.e. from top dead center to bottom dead center.

a couple observations:
1) wiping the chain off doesn't seem to make a difference, and the
drivetrain doesn't seem to be that dirty anyway (i don't ride through
rain, off road, etc..)
2) had a new sealed cartridge bottom bracket put in about a year ago or
so by my lbs.
3) it's an old fuji road bike conversion, if that makes any difference.
4) the bike has never been totally whisper quiet--there's always been
an off and on chain-meshing-chainring sound, if that's indicative of
anything off in the drivetrain.

any theories/diagnoses--chainline off? chain too tight? crapped out bb?
overactive imagination?
thanks!
~vincent.

I've also noticed that my worn chain ring makes a feeling/sound kind of
like that. I can only notice it on very smooth surfaces: freshly paved
roads or indoors on linoleum, for example.

I had this problem myself and it turned out to be an out of round chainring.

What happens as you pedal is that the chain tension increases/decreases. As
it increases it vibrates at a higher and higher frequency and sounds like a
crunchy/grindy sound and you can feel the vibration in your feet. This is
especially true when the chain is already under tension, say like when
you're grinding up a hill.

I replaced my el-cheapo chainring with a Salsa and it works much better.

J.

wrote in message
oups.com...
autopi wrote:
hi there, i have a question about a noise/grinding sensation coming
from the drive train on my fixie. it's a sort of
crunchy/grinding/sand-in-the-works sort of noise, and i can feel it a
bit through my pedals (spd clones)--in particular, on the drive side.
it seems to be most noticeable when powering uphill, and it might be my
imagination, but seems to be concentrated in the power part of the
stroke, i.e. from top dead center to bottom dead center.

a couple observations:
1) wiping the chain off doesn't seem to make a difference, and the
drivetrain doesn't seem to be that dirty anyway (i don't ride through
rain, off road, etc..)
2) had a new sealed cartridge bottom bracket put in about a year ago or
so by my lbs.
3) it's an old fuji road bike conversion, if that makes any difference.
4) the bike has never been totally whisper quiet--there's always been
an off and on chain-meshing-chainring sound, if that's indicative of
anything off in the drivetrain.

any theories/diagnoses--chainline off? chain too tight? crapped out bb?
overactive imagination?
thanks!
~vincent.

I've also noticed that my worn chain ring makes a feeling/sound kind of
like that. I can only notice it on very smooth surfaces: freshly paved
roads or indoors on linoleum, for example.