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How can you tell when a chainring is worn?

post #1 of 30
Thread Starter 
Charles Smith writes:

> I'm looking at this one I just bought (used) and it looks great. The
> chain and the cassette are new and 10 speed so I'm concerned and
> don't want to wear them out quickly. Is there something I could
> measure?


Yes, measure the chain, not the sprockets. Sprockets take care of
themselves. They either mesh effectively or skip under load.
Chainwheels just keeps on working until teeth break off. I have never
seen a chainwheel that won't drive a new or worn chain but I have seen
plenty of rear sprockets over which the chain skips under load. A
worn (elongated) chain is what wears out sprockets.

http://www.sheldonbrown.com/brandt/chain-care.html

Jobst Brandt
jobst.brandt@stanfordalumni.org
post #2 of 30

Re: How can you tell when a chainring is worn?

On Mon, 10 Jan 2005 05:20:44 GMT,
jobst.brandt@stanfordalumni.org wrote:

>Charles Smith writes:
>
>> I'm looking at this one I just bought (used) and it looks great. The
>> chain and the cassette are new and 10 speed so I'm concerned and
>> don't want to wear them out quickly. Is there something I could
>> measure?

>
>Yes, measure the chain, not the sprockets. Sprockets take care of
>themselves. They either mesh effectively or skip under load.
>Chainwheels just keeps on working until teeth break off. I have never
>seen a chainwheel that won't drive a new or worn chain but I have seen
>plenty of rear sprockets over which the chain skips under load. A
>worn (elongated) chain is what wears out sprockets.
>
>http://www.sheldonbrown.com/brandt/chain-care.html
>
>Jobst Brandt
>jobst.brandt@stanfordalumni.org


Dear Jobst,

About a year ago, I replaced my chain and rear cluster.

The new chain came off my worn front 53-tooth chain ring the
moment that I pushed down on the pedal to roll out the
driveway.

The new chain came off the worn chain ring twice more,
despite the derailleur being apparently sitting in the right
place.

The new chain worked fine on the 39-tooth chain ring, which
is used on onlyl about 15% of my daily ride, so I replaced
the big chain ring.

The new front chain ring worked fine.

No broken teeth on the old chain ring, just badly worn teeth
when compared in profile to a new chain ring. I rotated them
to match the irregular factory tooth shaping.

Maybe this was a fluke? If rear cogs can wear out enough to
skip, shouldn't front cogs be able to do the same?

Carl Fogel
post #3 of 30

Re: How can you tell when a chainring is worn?

carlfogel@comcast.net wrote:

> The new chain came off my worn front 53-tooth chain ring the
> moment that I pushed down on the pedal to roll out the
> driveway.
>
> The new chain came off the worn chain ring twice more,
> despite the derailleur being apparently sitting in the right
> place.
>
> The new chain worked fine on the 39-tooth chain ring, which
> is used on onlyl about 15% of my daily ride, so I replaced
> the big chain ring.
>
> The new front chain ring worked fine.
>
> No broken teeth on the old chain ring, just badly worn teeth
> when compared in profile to a new chain ring. I rotated them
> to match the irregular factory tooth shaping.
>
> Maybe this was a fluke? If rear cogs can wear out enough to
> skip, shouldn't front cogs be able to do the same?


I've also had a chainring worn down to this state. It was skipping very
badly on the large ring: occasionally badly enough to unship the chain.
It was actually getting dangerous as it would be most likely to skip
when the greatest load was being placed on it - either starting off or
getting out of the saddle to climb. There were no broken teeth; they
were just exremely worn.

The middle ring and granny did not skip at all. The worn chainring was
also prone to chain suck when changing down forn the large ring to the
middle. The large ring was a 46 tooth Shimano LX.

--
Dave...
post #4 of 30

Re: How can you tell when a chainring is worn?

On Mon, 10 Jan 2005 05:20:44 GMT, jobst.brandt@stanfordalumni.org
wrote:

> I have never
>seen a chainwheel that won't drive a new or worn chain but I have seen
>plenty of rear sprockets over which the chain skips under load.


I have to agree that in most cases, it is a worn rear sprocket/chain
that causes skipping... but...
On my mountain bike... i've had the 32T ring skip. Took a while to
figure out what was happening... started after putting on a new chain
and cassette. From a standstill, I could stand on the cranks and the
chain would slip on the chainring.

Our riding is mostly in wet/muddy conditions.. and I get maybe 400
miles on a chain and have to replace the cassettes after 2-3 chains
have been replaced and have to replace the chainrings at least once
per year.

charlieb in ct
post #5 of 30

Re: How can you tell when a chainring is worn?

"Jeff Starr" <jstarr@animalpc.com> wrote in message
news:et65u0pe7geifbn32d3flre880acuhe4re@4ax.com...
> On Mon, 10 Jan 2005 14:11:30 GMT, Charles Beristain
> <charlieb@prodigy.net> wrote:
>
>
> >
> >Our riding is mostly in wet/muddy conditions.. and I get maybe 400
> >miles on a chain and have to replace the cassettes after 2-3 chains
> >have been replaced and have to replace the chainrings at least once
> >per year.
> >
> >charlieb in ct

>
> Hi, I hope you meant 4000[four thousand], not 400[four hundred] miles
> If you put on a reasonable amount of miles per year, at 400, it would
> get costly.
>
> So, is the above correct?, If so, how many chains did you go through
> last year?


When you ride mostly in wet and muddy conditions as I do here during
wintertime in the Netherlands I get about 2500 km out of a chain and I take
good care of my bike. So 400 miles is not much, but 4000 miles is way to
high.

Lou
post #6 of 30

Re: How can you tell when a chainring is worn?

Lou Holtman wrote:

>
> When you ride mostly in wet and muddy conditions as I do here during
> wintertime in the Netherlands I get about 2500 km out of a chain and I take
> good care of my bike. So 400 miles is not much, but 4000 miles is way to
> high.


Please don't mention the X-word Lou, you know Jan couldn't cope
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl
post #7 of 30

Re: How can you tell when a chainring is worn?

On Mon, 10 Jan 2005 14:11:30 GMT, Charles Beristain
<charlieb@prodigy.net> wrote:

>On my mountain bike... i've had the 32T ring skip. Took a while to
>figure out what was happening... started after putting on a new chain
>and cassette. From a standstill, I could stand on the cranks and the
>chain would slip on the chainring.


I had and maybe still have in the garage:

A 42t Campy middle ring that skipped with new chain and sprockets.
Teeth are worn in one area and it would probably work ok if rotated on
crankarm.

A 43t DA ring that Gerry Tatrai used for RAAM that skipped. The teeth
are wave shaped and needle sharp.
post #8 of 30

Re: How can you tell when a chainring is worn?

On 10 Jan 2005 01:20:07 -0800, "dkahn400"
<dkahn400@yahoo.co.uk> wrote:

>carlfogel@comcast.net wrote:
>
>> The new chain came off my worn front 53-tooth chain ring the
>> moment that I pushed down on the pedal to roll out the
>> driveway.
>>
>> The new chain came off the worn chain ring twice more,
>> despite the derailleur being apparently sitting in the right
>> place.
>>
>> The new chain worked fine on the 39-tooth chain ring, which
>> is used on onlyl about 15% of my daily ride, so I replaced
>> the big chain ring.
>>
>> The new front chain ring worked fine.
>>
>> No broken teeth on the old chain ring, just badly worn teeth
>> when compared in profile to a new chain ring. I rotated them
>> to match the irregular factory tooth shaping.
>>
>> Maybe this was a fluke? If rear cogs can wear out enough to
>> skip, shouldn't front cogs be able to do the same?

>
>I've also had a chainring worn down to this state. It was skipping very
>badly on the large ring: occasionally badly enough to unship the chain.
>It was actually getting dangerous as it would be most likely to skip
>when the greatest load was being placed on it - either starting off or
>getting out of the saddle to climb. There were no broken teeth; they
>were just exremely worn.
>
>The middle ring and granny did not skip at all. The worn chainring was
>also prone to chain suck when changing down forn the large ring to the
>middle. The large ring was a 46 tooth Shimano LX.


Dear Dave,

What puzzled me was that my worn chain worked fine on my
worn front 53-tooth chain ring, but the new chain/rear
cluster combination stripped the chain off the front
instantly (same stodgy sram pc48, same number of links, same
rear cluster, and then the same front ring). And both the
old and the new chains stayed put on the small 39-tooth
ring.

As far as I can see, the front ring's teeth, no matter how
worn they were, had to stay the same distance apart, so I
can't figure out why an old worn chain would stay in place
while a new chain that should have fit better would come
off.

That's why I'm wondering if Jobst or someone else is going
to explain that it was a fluke or that something else was
involved. But it certainly reminded me of how a worn rear
cog starts to skip and seems to get worse with a new
chain--which may be another misconception that I need
cleared up.

Of course, if I replaced my chains sooner, I might not get
into such situations.

Carl Fogel
post #9 of 30

Re: How can you tell when a chainring is worn?

On Mon, 10 Jan 2005 09:19:11 -0600, Jeff Starr <jstarr@animalpc.com>
wrote:

>Hi, I hope you meant 4000[four thousand], not 400[four hundred] miles
>If you put on a reasonable amount of miles per year, at 400, it would
>get costly.
>
>So, is the above correct?, If so, how many chains did you go through
>last year?


nope-- 400 miles .. I do about 3-4000miles per year... I wipe the
chain off and relube it with "prolink" after each ride.

charlieb in ct.
post #10 of 30
Thread Starter 

Re: How can you tell when a chainring is worn?

Carl Fogel writes:

>>> I'm looking at this one I just bought (used) and it looks
>>> great. The chain and the cassette are new and 10 speed so I'm
>>> concerned and don't want to wear them out quickly. Is there
>>> something I could measure?


>> Yes, measure the chain, not the sprockets. Sprockets take care of
>> themselves. They either mesh effectively or skip under load.
>> Chainwheels just keeps on working until teeth break off. I have
>> never seen a chainwheel that won't drive a new or worn chain but I
>> have seen plenty of rear sprockets over which the chain skips under
>> load. A worn (elongated) chain is what wears out sprockets.


> About a year ago, I replaced my chain and rear cluster.


> The new chain came off my worn front 53-tooth chain ring the moment
> that I pushed down on the pedal to roll out the driveway.


> The new chain came off the worn chain ring twice more, despite the
> derailleur being apparently sitting in the right place.


> The new chain worked fine on the 39-tooth chain ring, which is used
> on only about 15% of my daily ride, so I replaced the big chain
> ring.


I don't know what sort of chain ring you have or what other effects
were involved, but I have ridden chainrings until there was barely any
width and length of full height teeth left. I'll let the thing run
until it fails. I can always use the other CW to ride home, it not
being tiny.

I think bicycle shops can attest to there being no need to replace a
chainwheel until the teeth are gone. In what manner did your chain
"come off". I can't visualize how the chain did not stay on the
sprocket. Was the chain in a strong cross-over angle, left CW of
three to rightmost rear sprocket of 10? I think this needs some
qualification. Of course since I ride with two CW's and a 6-speed FW,
I may be better off.

> The new front chain ring worked fine.


> No broken teeth on the old chain ring, just badly worn teeth when
> compared in profile to a new chain ring. I rotated them to match
> the irregular factory tooth shaping.


> Maybe this was a fluke? If rear cogs can wear out enough to skip,
> shouldn't front cogs be able to do the same?


I would invest in a bit of repeatability before buying a new CW.

Jobst Brandt
jobst.brandt@stanfordalumni.org
post #11 of 30

Re: How can you tell when a chainring is worn?

jobst.brandt@stanfordalumni.org wrote:
> Carl Fogel writes:
>
>>>> I'm looking at this one I just bought (used) and it looks
>>>> great. The chain and the cassette are new and 10 speed so I'm
>>>> concerned and don't want to wear them out quickly. Is there
>>>> something I could measure?

>
>>> Yes, measure the chain, not the sprockets. Sprockets take care of
>>> themselves. They either mesh effectively or skip under load.
>>> Chainwheels just keeps on working until teeth break off. I have
>>> never seen a chainwheel that won't drive a new or worn chain but I
>>> have seen plenty of rear sprockets over which the chain skips under
>>> load. A worn (elongated) chain is what wears out sprockets.

>
>> About a year ago, I replaced my chain and rear cluster.

>
>> The new chain came off my worn front 53-tooth chain ring the moment
>> that I pushed down on the pedal to roll out the driveway.

>
>> The new chain came off the worn chain ring twice more, despite the
>> derailleur being apparently sitting in the right place.

>
>> The new chain worked fine on the 39-tooth chain ring, which is used
>> on only about 15% of my daily ride, so I replaced the big chain
>> ring.

>
> I don't know what sort of chain ring you have or what other effects
> were involved, but I have ridden chainrings until there was barely any
> width and length of full height teeth left. I'll let the thing run
> until it fails. I can always use the other CW to ride home, it not
> being tiny.
>
> I think bicycle shops can attest to there being no need to replace a
> chainwheel until the teeth are gone. In what manner did your chain
> "come off". I can't visualize how the chain did not stay on the
> sprocket. Was the chain in a strong cross-over angle, left CW of
> three to rightmost rear sprocket of 10? I think this needs some
> qualification. Of course since I ride with two CW's and a 6-speed FW,
> I may be better off.
>
>> The new front chain ring worked fine.

>
>> No broken teeth on the old chain ring, just badly worn teeth when
>> compared in profile to a new chain ring. I rotated them to match
>> the irregular factory tooth shaping.

>
>> Maybe this was a fluke? If rear cogs can wear out enough to skip,
>> shouldn't front cogs be able to do the same?

>
> I would invest in a bit of repeatability before buying a new CW.


Allow me to recap. Despite the experience of MANY people who've had chains
slip due to worn chain rings (in my case the middle rings on various mtb
cranksets), Jobst says it's not true so we all must be crazy, idiots, or
lying.

Just because it doesn't happen /easily/ on a road bike setup (especially an
old 12-speed), that doesn't mean it's not common on other types of
drivetrains and bikes. (In fact I have an XTR crankset gathering dust in my
garage right now, because I can't justify spending $70 for a new middle
ring. The old one LOOKS FINE, by the way, but will NOT hold a chain under
any significant power.)

I also have a TruVativ mtb triple that recently required a new middle ring
(after a new chain and cassette); fixed the skipping problem immediately.

Bill "we're not imagining this" S.
post #12 of 30

Re: How can you tell when a chainring is worn?

Charles Smith wrote:

> I'm looking at this one I just bought (used) and it looks great. The chain and the
> cassette are new and 10 speed so I'm concerned and don't want to wear them out
> quickly. Is there something I could measure?


It develops a hooked appearance. However, chainrings are always the
last thing to wear out and the last to cause any slipping problems. If
a chain lasts 2,000 miles then a cassette will do many chains (provided
you replaced them when 12 links reached 12 1/16" and no later) and a
decent chainring will do more than one cassette.

I make an exception for those tinfoil things Shimano uses in place of
road chainrings these days ;-)
post #13 of 30

Re: How can you tell when a chainring is worn?

Drew Eckhardt wrote:
> In article <9jzEd.1092$m31.13090@typhoon.sonic.net>,
> <jobst.brandt@stanfordalumni.org> wrote:
>> I think bicycle shops can attest to there being no need to replace a
>> chainwheel until the teeth are gone. In what manner did your chain
>> "come off". I can't visualize how the chain did not stay on the
>> sprocket. Was the chain in a strong cross-over angle, left CW of
>> three to rightmost rear sprocket of 10?

>
> With properly adjusted derailleurs and a worn big ring I've had the
> chain drop off to the middle ring (Campy Racing-T, 9-speed 13-23) a
> few times when in one of the 2-3 bigger cogs. I was blacking out
> from the first crash while accelerating, and had a jammed thumb for
> a few months from the second while climbing. I then replaced the
> crankset with a compact double that had brand new rings.
>
> The next time my chain rings look worn I'm going to replace them.


But...but...Jobst says it's not necessary! Must be true, right?!?
post #14 of 30

Re: How can you tell when a chainring is worn?

I've had a couple of chainwheels which were badly worn and the chains
started to come off them, off sideways. They were badly worn so that the
teeth were sharp triangles. Teeth were not missing.
post #15 of 30

Re: How can you tell when a chainring is worn?

On Mon, 10 Jan 2005 17:54:13 GMT,
jobst.brandt@stanfordalumni.org wrote:

>Carl Fogel writes:
>
>>>> I'm looking at this one I just bought (used) and it looks
>>>> great. The chain and the cassette are new and 10 speed so I'm
>>>> concerned and don't want to wear them out quickly. Is there
>>>> something I could measure?

>
>>> Yes, measure the chain, not the sprockets. Sprockets take care of
>>> themselves. They either mesh effectively or skip under load.
>>> Chainwheels just keeps on working until teeth break off. I have
>>> never seen a chainwheel that won't drive a new or worn chain but I
>>> have seen plenty of rear sprockets over which the chain skips under
>>> load. A worn (elongated) chain is what wears out sprockets.

>
>> About a year ago, I replaced my chain and rear cluster.

>
>> The new chain came off my worn front 53-tooth chain ring the moment
>> that I pushed down on the pedal to roll out the driveway.

>
>> The new chain came off the worn chain ring twice more, despite the
>> derailleur being apparently sitting in the right place.

>
>> The new chain worked fine on the 39-tooth chain ring, which is used
>> on only about 15% of my daily ride, so I replaced the big chain
>> ring.

>
>I don't know what sort of chain ring you have or what other effects
>were involved, but I have ridden chainrings until there was barely any
>width and length of full height teeth left. I'll let the thing run
>until it fails. I can always use the other CW to ride home, it not
>being tiny.
>
>I think bicycle shops can attest to there being no need to replace a
>chainwheel until the teeth are gone. In what manner did your chain
>"come off". I can't visualize how the chain did not stay on the
>sprocket. Was the chain in a strong cross-over angle, left CW of
>three to rightmost rear sprocket of 10? I think this needs some
>qualification. Of course since I ride with two CW's and a 6-speed FW,
>I may be better off.
>
>> The new front chain ring worked fine.

>
>> No broken teeth on the old chain ring, just badly worn teeth when
>> compared in profile to a new chain ring. I rotated them to match
>> the irregular factory tooth shaping.

>
>> Maybe this was a fluke? If rear cogs can wear out enough to skip,
>> shouldn't front cogs be able to do the same?

>
>I would invest in a bit of repeatability before buying a new CW.
>
>Jobst Brandt
>jobst.brandt@stanfordalumni.org


Dear Jobst,

I can't think of anything odd, beyond the new chain
stripping off the worn front 53-tooth repeatedly as soon as
I stepped on the pedal to roll down the driveway into the
street.

The chain was sitting on the usual start-out gear of #4 on a
new 7-cog Shimano 11 x 28--I'd just replaced both chain and
rear cluster.

Same sram pc48 chain, same number of links, same quick
connect link--hell, front wheel lined up on the same crack
as always in the driveway.

The new chain just stripped off the front 53-tooth and out
onto the pedal side of things, not down onto the smaller
ring. I can't think of much else to describe it.

It happened three times as soon as I stepped onto the pedal
to start off.

I tried the chain on the 39-tooth and it worked fine, so I
put a new 53-tooth on and rode off without any problem.

Here's a picture of some of the teeth:

http://home.comcast.net/~carlfogel/d.../wornteeth.jpg

None of the others are broken. I figured that cahin ring was
just worn out, but I admit that I can't see why a worn chain
ring would fine the previous day with the worn chain and
then strip off so reliably with a new chain fifteen miles
later the next day.

Carl Fogel
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