How to tell if cogs/chainrings need replacement?

I have a gauge to measure chain wear, and if I'm without it I'll test
the chain by pulling at the middle of the chainring run and feeling
the slack.

Sometimes a new chain on an old cassette or chainring skips worse than
the old chain.. but it's hard to tell when this is going to happen and
I find I'm often wrong. That is, a chainring I thought was fine skips,
or I replace a cassette that I'm not totally sure needed replacing.

Is there are good method for determining how much life cogs have left?
Do you just 'look at them'? What do you look for?

Thanks,

Adam

wrote:

Is there are good method for determining how much life cogs
have left? Do you just 'look at them'? What do you look for?

The only effective method is to test the sprockets with a "tight"
chain under load. And the cheapest way to do that is to ride and
push with a new chain (using smaller chainrings loads the chain
up more, of course).

Rohloff thoughtfully make a tool so that you can do this test off-
bike by emulating those conditions:
http://www.rohloff.de/en/products/hg...eck/index.html

John

wrote:
I have a gauge to measure chain wear, and if I'm without it I'll test
the chain by pulling at the middle of the chainring run and feeling
the slack.

Sometimes a new chain on an old cassette or chainring skips worse than
the old chain.. but it's hard to tell when this is going to happen and
I find I'm often wrong. That is, a chainring I thought was fine skips,
or I replace a cassette that I'm not totally sure needed replacing.

Is there are good method for determining how much life cogs have left?
Do you just 'look at them'? What do you look for?

When replacing a chain, I just go for a test ride to see if the new chain is
working on the old sprockets. I don't replace the sprockets (for wear
reasons) before there is skipping in actual normal use.

When not replacing chains and using the same chain until it wears out,
again, I just carry on until it doesn't work. At first there is just a
slight occasional skip, and then many more miles are possible without
/major/ problem.

I think you only need to replace the sprockets or chainrings early (before
one is worn out) if going on tour or racing. It's really not big deal
otherwise for normal recreational or utility cycling.

~PB

wrote:
I have a gauge to measure chain wear, and if I'm without it I'll test
the chain by pulling at the middle of the chainring run and feeling
the slack.

Sometimes a new chain on an old cassette or chainring skips worse than
the old chain.. but it's hard to tell when this is going to happen and
I find I'm often wrong. That is, a chainring I thought was fine skips,
or I replace a cassette that I'm not totally sure needed replacing.

Is there are good method for determining how much life cogs have left?
Do you just 'look at them'? What do you look for?

Thanks,

Adam

http://www.sheldonbrown.com/chains.html#wear

On Apr 2, 6:39*am, "Pete Biggs"
wrote:
wrote:
I have a gauge to measure chain wear, and if I'm without it I'll test
the chain by pulling at the middle of the chainring run and feeling
the slack.

Sometimes a new chain on an old cassette or chainring skips worse than
the old chain.. but it's hard to tell when this is going to happen and
I find I'm often wrong. That is, a chainring I thought was fine skips,
or I replace a cassette that I'm not totally sure needed replacing.

Is there are good method for determining how much life cogs have left?
Do you just 'look at them'? What do you look for?

When replacing a chain, I just go for a test ride to see if the new chain is
working on the old sprockets. *I don't replace the sprockets (for wear
reasons) before there is skipping in actual normal use.

When not replacing chains and using the same chain until it wears out,
again, I just carry on until it doesn't work. *At first there is just a
slight occasional skip, and then many more miles are possible without
/major/ problem.

I think you only need to replace the sprockets or chainrings early (before
one is worn out) if going on tour or racing. *It's really not big deal
otherwise for normal recreational or utility cycling.

~PB

If you ride with a worn chain too long it damages the pitch of your
cogs and they have to be replaced, however if you replace a worn chain
early enough you may find skipping initially but that soon goes away.

On 2 Apr, 05:15, wrote:
I have a gauge to measure chain wear, and if I'm without it I'll test
the chain by pulling at the middle of the chainring run and feeling
the slack.

Sometimes a new chain on an old cassette or chainring skips worse than
the old chain.. but it's hard to tell when this is going to happen and
I find I'm often wrong. That is, a chainring I thought was fine skips,
or I replace a cassette that I'm not totally sure needed replacing.

Is there are good method for determining how much life cogs have left?
Do you just 'look at them'? What do you look for?

Hooking or rounding of the teeth when viewed from the right of the
bike. Wear in the sprockets which does not radically alter the tooth
profile is totally acceptable. The leading and trailing edge of the
sprocket teeth should be of similar profile. You have to eyeball it
or just accept that if the chain doesn't stick or slip it's OK. Start
with 3 new chains with a new sprocket set and rotate the use of the
chains to obtain good lifespan of all. Old sprockets don't like new
chains because the shorter pitch(old to new) catches on the trailing
edge of tooth trying to engage on the slck side of the chain.

TJ

TJ

On Thu, 2 Apr 2009 07:01:33 -0700 (PDT), Nick L Plate wrote:

Wear in the sprockets which does not radically alter the tooth
profile is totally acceptable.

No.

Wear which increases the distance between tooth faces is (if sufficient)
bad, irrespective of the new, worn, shape.

On Apr 2, 10:01*am, Nick L Plate wrote:

*Wear in the sprockets which does not radically alter the tooth
profile is totally acceptable. * The leading and trailing edge of the
sprocket teeth should be of similar profile.

Once upon a time, maybe, but not any more. Look at
http://harriscyclery.net/itemdetails.cfm?ID=732

These days many sprocket teeth are very asymmetrical right out of the
box. It helps the chain shift quickly from one cog to the next.

- Frank Krygowski

On 2 Apr, 17:06, Frank Krygowski wrote:
On Apr 2, 10:01*am, Nick L Plate wrote:

*Wear in the sprockets which does not radically alter the tooth
profile is totally acceptable. * The leading and trailing edge of the
sprocket teeth should be of similar profile.

Once upon a time, maybe, but not any more. *Look athttp://harriscyclery..net/itemdetails.cfm?ID=732

These days many sprocket teeth are very asymmetrical right out of the
box. *It helps the chain shift quickly from one cog to the next.


But only on one or two teeth, asessment would not be made on the
goofy teeth, but on the regular ones.

TJ

On Apr 2, 11:17*am, wrote:

Although cogs wear, their sprockets require replacement when worn,
cogs of a cogwheel not being separately replaceable. *Meanwhile, worn
driving sprockets work reasonably well with both new and worn chains

Only up to a point. I just replaced the large chainring on my most
used bike a few days ago after it started to skip. The skip would
occur when putting substantial tension on the change in combination
with a bump that would impart some vertical motion to the chain. Then
the chain would skip multiple teeth making considerable noise and
sometimes come off the ring altogether. The same symptoms had
occurred earlier and were cured by flipping the chainring over so the
teeth would engage the chain on the opposite face. Now that both
sides were worn it was time for replacement of the ring and that again
stopped the skipping.

while driven sprockets on derailleur bicycles will skip, not allowing
the new chain to engage them after having been run with a worn chain.
Under load, if a new chain skips on worn rear sprockets, it will
continue to skip until it wears to match the elongated pitch of the
previous chain.

Jobst Brandt