small cog noise/roughness?

Camilo said:

Hi - I did a quick search and couldn't really find an answer to this
question.

I have recently graduated from a mediocre (but OK) bike to a very nice
one. I bought the "new" bike used. It works just fine on the road
(I've only ridden 30 minutes, because of the rain). It is a full
Ultergra group, with a Durace rear derailleur. Visually it is in
excellent, lightly used condition, appears to be well maintained. On
the stand, it shifts perfectly both front and rear and it is so
obviously smoother running than my old Shimano Exage group. I just
KNOW it will get me up those hills so much better 8-) (I'm joking - I
know the motor hasn't changed, but it will be more fun to ride
anyway).

For what it's worth, I do a lot of my own wrenching if I have the
time, but I'm no expert. I do lube and adjustments. I've actually
done rebuild of hubs, headset, bottom bracket, etc. in the past, but
haven't lately.

I thought I'd ask here before I bring it in to my trusted mechanic,
just because I'd rather take care of it if it's simple.

The following is what happens when spinning the crank on the repair
stand:

When the chain is on the smallest 3 rear cogs and the large front
chain wheel, it really is rough and noisy. A very "crude" (as opposed
to fine) vibration and accompanying sound when spinning the crank. The
vibration and noise is not there when the wheel is spinning free. To
me it sounds and feels like the rear cog and chain are actually
somehow vibrating at every chain/cog poiint - the "frequency" of the
noise and vibration seems to be the same as the rate the cog in
question is spinning when being pulled by the chain. As I said, when
spinning free (the chain is not pulling the cog wheel), it is just
normal freewheel sound.

This does not happen in any other situation than smallest three rear
cogs, large chain wheel. It seems to get worse as the cog gets
smaller.

It is not the sort of clattering sound you hear when the shifting is
slightly off (the sound that is remedied by minor adjustment of the
shifting cable).

Just for grins, I compared to my old bike - that old bike is not in
'perfect' running order, but shifts fine and the chain and derailleurs
are properly maintained. First impression: HUGE, HUGE difference in
the smoothness and effotlessness of the entire drive train (new bike
being BETTER, much better).

Second impression: although the old bike is not as smooth and easy in
general, it does not make this rough vibration on those lower cogs, or
at any time.

Thanks in advance for any pointers.

A 11-12 or 13 T cog is just to small to run with a 1/2" pitch chain.
Rough is a good description.

Lou

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

Camilo said:

Hi - I did a quick search and couldn't really find an answer to this
question.

I have recently graduated from a mediocre (but OK) bike to a very nice
one. I bought the "new" bike used. It works just fine on the road
(I've only ridden 30 minutes, because of the rain). It is a full
Ultergra group, with a Durace rear derailleur. Visually it is in
excellent, lightly used condition, appears to be well maintained. On
the stand, it shifts perfectly both front and rear and it is so
obviously smoother running than my old Shimano Exage group. I just
KNOW it will get me up those hills so much better 8-) (I'm joking - I
know the motor hasn't changed, but it will be more fun to ride
anyway).

For what it's worth, I do a lot of my own wrenching if I have the
time, but I'm no expert. I do lube and adjustments. I've actually
done rebuild of hubs, headset, bottom bracket, etc. in the past, but
haven't lately.

I thought I'd ask here before I bring it in to my trusted mechanic,
just because I'd rather take care of it if it's simple.

The following is what happens when spinning the crank on the repair
stand:

When the chain is on the smallest 3 rear cogs and the large front
chain wheel, it really is rough and noisy. A very "crude" (as opposed
to fine) vibration and accompanying sound when spinning the crank. The
vibration and noise is not there when the wheel is spinning free. To
me it sounds and feels like the rear cog and chain are actually
somehow vibrating at every chain/cog poiint - the "frequency" of the
noise and vibration seems to be the same as the rate the cog in
question is spinning when being pulled by the chain. As I said, when
spinning free (the chain is not pulling the cog wheel), it is just
normal freewheel sound.

This does not happen in any other situation than smallest three rear
cogs, large chain wheel. It seems to get worse as the cog gets
smaller.

It is not the sort of clattering sound you hear when the shifting is
slightly off (the sound that is remedied by minor adjustment of the
shifting cable).

Just for grins, I compared to my old bike - that old bike is not in
'perfect' running order, but shifts fine and the chain and derailleurs
are properly maintained. First impression: HUGE, HUGE difference in
the smoothness and effotlessness of the entire drive train (new bike
being BETTER, much better).

Second impression: although the old bike is not as smooth and easy in
general, it does not make this rough vibration on those lower cogs, or
at any time.

Thanks in advance for any pointers.

Have a good look; they (and/or the chain) may well be worn enough to cause
the "roughness".

Small cogs wear more quickly.

Camilo said:

Hi - I did a quick search and couldn't really find an answer to this
question.

I have recently graduated from a mediocre (but OK) bike to a very nice
one. I bought the "new" bike used. It works just fine on the road
(I've only ridden 30 minutes, because of the rain). It is a full
Ultergra group, with a Durace rear derailleur. Visually it is in
excellent, lightly used condition, appears to be well maintained. On
the stand, it shifts perfectly both front and rear and it is so
obviously smoother running than my old Shimano Exage group. I just
KNOW it will get me up those hills so much better 8-) (I'm joking - I
know the motor hasn't changed, but it will be more fun to ride
anyway).

For what it's worth, I do a lot of my own wrenching if I have the
time, but I'm no expert. I do lube and adjustments. I've actually
done rebuild of hubs, headset, bottom bracket, etc. in the past, but
haven't lately.

I thought I'd ask here before I bring it in to my trusted mechanic,
just because I'd rather take care of it if it's simple.

The following is what happens when spinning the crank on the repair
stand:

When the chain is on the smallest 3 rear cogs and the large front
chain wheel, it really is rough and noisy. A very "crude" (as opposed
to fine) vibration and accompanying sound when spinning the crank. The
vibration and noise is not there when the wheel is spinning free. To
me it sounds and feels like the rear cog and chain are actually
somehow vibrating at every chain/cog poiint - the "frequency" of the
noise and vibration seems to be the same as the rate the cog in
question is spinning when being pulled by the chain. As I said, when
spinning free (the chain is not pulling the cog wheel), it is just
normal freewheel sound.

This does not happen in any other situation than smallest three rear
cogs, large chain wheel. It seems to get worse as the cog gets
smaller.

It is not the sort of clattering sound you hear when the shifting is
slightly off (the sound that is remedied by minor adjustment of the
shifting cable).

Just for grins, I compared to my old bike - that old bike is not in
'perfect' running order, but shifts fine and the chain and derailleurs
are properly maintained. First impression: HUGE, HUGE difference in
the smoothness and effotlessness of the entire drive train (new bike
being BETTER, much better).

Second impression: although the old bike is not as smooth and easy in
general, it does not make this rough vibration on those lower cogs, or
at any time.

Thanks in advance for any pointers.

On a new sprocket tooth, the surface that the chain rollers press against is perpendicular to the pull of the chain. The worn teeth have become ramps, causing the chain to ride up under load.
This is common where smaller cogs are used more/Wear Faster.
New Chain and New Cassette combination usually resolves this.
If you ride with worn cogs you will wear out the chain faster.

In article
<[email hidden]>,

Camilo said:

Hi - I did a quick search and couldn't really find an answer to this
question.

I have recently graduated from a mediocre (but OK) bike to a very nice
one. I bought the "new" bike used. It works just fine on the road
(I've only ridden 30 minutes, because of the rain). It is a full
Ultergra group, with a Durace rear derailleur. Visually it is in
excellent, lightly used condition, appears to be well maintained. On
the stand, it shifts perfectly both front and rear and it is so
obviously smoother running than my old Shimano Exage group. I just
KNOW it will get me up those hills so much better 8-) (I'm joking - I
know the motor hasn't changed, but it will be more fun to ride
anyway).

For what it's worth, I do a lot of my own wrenching if I have the
time, but I'm no expert. I do lube and adjustments. I've actually
done rebuild of hubs, headset, bottom bracket, etc. in the past, but
haven't lately.

I thought I'd ask here before I bring it in to my trusted mechanic,
just because I'd rather take care of it if it's simple.

The following is what happens when spinning the crank on the repair
stand:

When the chain is on the smallest 3 rear cogs and the large front
chain wheel, it really is rough and noisy. A very "crude" (as opposed
to fine) vibration and accompanying sound when spinning the crank. The
vibration and noise is not there when the wheel is spinning free. To
me it sounds and feels like the rear cog and chain are actually
somehow vibrating at every chain/cog poiint - the "frequency" of the
noise and vibration seems to be the same as the rate the cog in
question is spinning when being pulled by the chain. As I said, when
spinning free (the chain is not pulling the cog wheel), it is just
normal freewheel sound.

This does not happen in any other situation than smallest three rear
cogs, large chain wheel. It seems to get worse as the cog gets
smaller.

It is not the sort of clattering sound you hear when the shifting is
slightly off (the sound that is remedied by minor adjustment of the
shifting cable).

Just for grins, I compared to my old bike - that old bike is not in
'perfect' running order, but shifts fine and the chain and derailleurs
are properly maintained. First impression: HUGE, HUGE difference in
the smoothness and effotlessness of the entire drive train (new bike
being BETTER, much better).

Second impression: although the old bike is not as smooth and easy in
general, it does not make this rough vibration on those lower cogs, or
at any time.

Thanks in advance for any pointers.

First be sure the indexing of the derailleur is spot on.
Next measure the chain for wear. Replace if necessary.
If it is still rough, the cassette gears may be worn.

You did lubricate the chain?

--
Michael Press

new chain, new 14-11 cogs are normally noisy: a break in period on
larger cogs is best.

Quoted post said:

new chain, new 14-11 cogs are normally noisy: a break in period on
larger cogs is best.

While it's not entirely incorrect to say small cogs (<13th) are rough,
this sounds excessive.

Measure the chain for ware. If worn replace. (Read how to measure @
rbt faq or Sheldon Browns web site. Or buy the Rohloff Caliber 2 chain
checker or Park's copy of it, the CC-3. Personally I don't like Parks
other chain checker, the CC-2. It can easily be out of calibration).
Lube the chain. If that still doesn't fix it, replace the 3 or 4
smallest cogs. I also have the Rohloff HG_IG Check, which works fairly
well for small cogs except 11th'ers, but not well enough that I'd
recommend it to others.
Also if you can talk to the previous owner, find out if he is a 'big
gear' masher. If so, the chances that the small cogs are shot is much
greater.
Best wishes, John

Thanks gentlemen. As soon as I have a chance, I'm going to measure
the chain (I do know how to do that, but didn't think of it!) and will
closely examine the cogs and do the other checks you all recommended.
I'll report back.