Chain noise on fixed wheel.

[Andrew Webster]

I have recently fitted out one of my bikes witha fixed wheel.

New chain (PC48), new sprocket (cyclo, yes, 3/32), old chainwheel.

I have a problem with continuous chain noise at the rear. It is a continuous metallic "hum".

I have spent a long time ajusting the chain line - it is just about perfect. Before the fixed
sprocket arrived I rode about 50 miles with a single speed freewheel which did not produce the
same noise.

I note that the tooth profile on the sprocket is rather narrower at the point than a multiple
freewheel sprocket (see http://www.sjscycles.com/store/cyclofixedsprocket332.jpg), could this be
the culprit?

Is there an obvious point I am missing here? Is the problem likely to be chain, sprocket,
chainwheel or what?

Thanks for any observations.

Andrew Webster

 

[Jim Beam]

looks cheap & nasty to me. even in the pic, the tooth profiles don't appear to be well made.
doubtless it will get quieter over time as it wears to fit the chain. best to get a decent sprocket
next time. they /are/ worth the extra money.

jb

Andrew Webster wrote:
> I have recently fitted out one of my bikes witha fixed wheel.
>
> New chain (PC48), new sprocket (cyclo, yes, 3/32), old chainwheel.
>
> I have a problem with continuous chain noise at the rear. It is a continuous metallic "hum".
>
> I have spent a long time ajusting the chain line - it is just about perfect. Before the fixed
> sprocket arrived I rode about 50 miles with a single speed freewheel which did not produce the
> same noise.
>
> I note that the tooth profile on the sprocket is rather narrower at the point than a multiple
> freewheel sprocket (see http://www.sjscycles.com/store/cyclofixedsprocket332.jpg), could this be
> the culprit?
>
> Is there an obvious point I am missing here? Is the problem likely to be chain, sprocket,
> chainwheel or what?
>
> Thanks for any observations.
>
> Andrew Webster

 

[Ant]

[email protected] (Andrew Webster) wrote in message
news:<[email protected]>...

> I have recently fitted out one of my bikes witha fixed wheel. New chain (PC48), new sprocket
> (cyclo, yes, 3/32), old chainwheel.

cyclo! (gasp!)

> I have a problem with continuous chain noise at the rear. It is a continuous metallic "hum".
>
> I have spent a long time ajusting the chain line - it is just about perfect. Before the fixed
> sprocket arrived I rode about 50 miles with a single speed freewheel which did not produce the
> same noise.
>
> I note that the tooth profile on the sprocket is rather narrower at the point than a multiple
> freewheel sprocket (see http://www.sjscycles.com/store/cyclofixedsprocket332.jpg), could this be
> the culprit?

i dunno, frankly. it would seem that you have eliminated chainline as the problem if you had no
noise from a freewheel. however, i shoudl mention that i have a cyclo on one of my fixies, and she's
quiet. i have also had a very expensive cog on another fixie with just slightly off chainline whihc
made a racket until i perfected the chainline. it may have made a difference that that particular
bike had particualrly short chainstays, accentuating the bad chainline, but who knows. finally,
though im sure you've taken care ofit, oil quiets things down quite a bit, IMO.

one last thoguht: you didnt change wheel dish/spacing between the freewheel and cog, did you? those
two drive sysmtes dont necessarily have the same chainline spedcs, do they? so perhaps the freewheel
gave a slightly better chainline.

cheers,

anthony

 

[Andrew Webster]

Thanks for these comments.

I think I'll just leave it a bit to see if the chain/sprocket "wear in" and if that fails buy a
different sprocket to see if that has any effect.

I don't do many miles on this bike so it could be a while before I find out which approach
works (if any).

Andrew Webster