Shaping Cassette Teeth

I have been getting some annoying noise from my new Chorus cassette's
smallest cog (13t) - and as those who dare to read my drivel know,
this is a major issue for me.

So I try flipping the chain end for end. Not the solution - noise
seems to come once per revolution of the cog. Can't see anything
going on spinning the crank backwards, so I flip the bike and slowly
turn the crank while observing the chain.

Huh. At one point, the chain actually hangs up (just slightly) on one
tooth due to the lateral force from the relationship between the big
ring in the front and the cog in the rear combined with the existing
shaping of the teeth. There is a significant transition between the
lateral positioning of the peak of the tooth from inboard to outboard
over the course of two teeth. The release of the chain from this
slightly caught position is causing some jangling. And no doubt
excessive wear on the chain.

Please note that the tooth is still within the confines of the limits
of the overall cog, i.e., it doesn't appear to be bent.

So, my question is: Is it reasonable to take a file or a dremel to
this tooth and give it a slight taper at one end so that the chain
slides over it, rather than hanging? Or perhaps put a slight bend on
it so that the transition between tooth peak location is not so
abrupt?

Since I use this cog infrequently, I am not concerned about shortening
its life and note as well, other teeth on this cog are significantly
thinner than this one.

TIA

D'ohBoy

On Jul 1, 3:23 pm, D'ohBoy wrote:
I have been getting some annoying noise from my new Chorus cassette's
smallest cog (13t) - and as those who dare to read my drivel know,
this is a major issue for me.

So I try flipping the chain end for end. Not the solution - noise
seems to come once per revolution of the cog. Can't see anything
going on spinning the crank backwards, so I flip the bike and slowly
turn the crank while observing the chain.

Huh. At one point, the chain actually hangs up (just slightly) on one
tooth due to the lateral force from the relationship between the big
ring in the front and the cog in the rear combined with the existing
shaping of the teeth. There is a significant transition between the
lateral positioning of the peak of the tooth from inboard to outboard
over the course of two teeth. The release of the chain from this
slightly caught position is causing some jangling. And no doubt
excessive wear on the chain.

Please note that the tooth is still within the confines of the limits
of the overall cog, i.e., it doesn't appear to be bent.

So, my question is: Is it reasonable to take a file or a dremel to
this tooth and give it a slight taper at one end so that the chain
slides over it, rather than hanging? Or perhaps put a slight bend on
it so that the transition between tooth peak location is not so
abrupt?

Since I use this cog infrequently, I am not concerned about shortening
its life and note as well, other teeth on this cog are significantly
thinner than this one.

TIA

D'ohBoy

I did just as you describe to my wife's 9-speed Mirage cassette. I
used an old rusty hand file.

Joseph

Hi, Joseph -

Well, after giving one of my other wheelsets a go - might as well
exhaust all options before taking a grinder to things - I found that
it had something to do with the bike, not the cassette.

This became apparent after a wheel that did not cause this noise on my
secondary bike caused the noise on primary bike. So what could be
causing the noise?

Long story short, I had a bent der hanger. Which is weird, because I
actually 'unbent' it last year as well. Can you coldset aluminum? I
have beaten a moderately taco-ed OP rim back into round, and bent this
hanger back into position before. Why would it go out of position
over time? I don't believe the bike has ever been knocked over,
definitely has not been crashed, and I never lay it drivetrain side
down.

Huh, guess I'll have to keep an eye on it.

D'ohBoy

On Jul 2, 4:11 am, D'ohBoy wrote:
Hi, Joseph -

Well, after giving one of my other wheelsets a go - might as well
exhaust all options before taking a grinder to things - I found that
it had something to do with the bike, not the cassette.

This became apparent after a wheel that did not cause this noise on my
secondary bike caused the noise on primary bike. So what could be
causing the noise?

Long story short, I had a bent der hanger. Which is weird, because I
actually 'unbent' it last year as well. Can you coldset aluminum? I
have beaten a moderately taco-ed OP rim back into round, and bent this
hanger back into position before. Why would it go out of position
over time? I don't believe the bike has ever been knocked over,
definitely has not been crashed, and I never lay it drivetrain side
down.

Huh, guess I'll have to keep an eye on it.

D'ohBoy

Hmm. Maybe my wife's was (is?) bent too, but in this case it seemed
more like a chainline and resultant angle of the chain from the
different chainwheel sizes that was at fault. Glad you got it worked
out!

Joseph