Chainring teeth?

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Jupestar
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Re: Chainring teeth?

Post by Jupestar »

James Up Hill wrote: 29 Nov 2022, 10:29pm Chain snapped today
You say the chain snapped, which suggests there was something wrong with it or fitted badly.

For a chain to snap after 1500 miles is very unlikely to be due to wear.

It may have been stretched as well, but they are two different things..

Chainring looks fine to me.
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Sweep
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Re: Chainring teeth?

Post by Sweep »

Cugel wrote: 30 Nov 2022, 8:39am

You'd need to be a super-robot to hold a steel rule steadily enough and then view its reading accurately enough (without parallax errors) to make such a measurement. A good vernier will do the job, though - if it really is a good one. The cheap ones are useful for comparative measurements but can be inaccurate for absolute measurements, as needed with testing a chain for wear.

There are good quality chain "stretch" testing tools of the "drops through the links or doesn't" kind. Look for those that claim to have been CNC cut to a fine tolerance. They tend to cost more than the two quid versions stamped out of a plate.


Cugel
Must admit I have always been a bit wary of my ability to pull off the steel-rule method, though I know it's favoured by many of the old pros on here, and maybe was also by brucey.
Do you recommend any patricular checker?
I run nothing above 9 speed and use two "drop-in" checkers.
Park CC-3 with 0.75 and 1.0 marks
A KMC thing with a single "drop-in" prong marked as 0.8

I change the chains when the KMC drops in.
Sweep
alexnharvey
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Re: Chainring teeth?

Post by alexnharvey »

One wants a tool that pushes the rollers in the same direction rather than in opposite directions, so that differences in roller wear do not confuse the measurement. Well explained in various articles online, and probably also in a too good to lose thread here
slowster
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Re: Chainring teeth?

Post by slowster »

Cugel wrote: 30 Nov 2022, 8:39am You'd need to be a super-robot to hold a steel rule steadily enough and then view its reading accurately enough (without parallax errors) to make such a measurement.
Have you tried it? I find it relatively easy to position the corner of one end of the rule over the centre of a pin, and keep it there by holding the rule and chain pressed against each other. Making a sufficiently accurate reading at the other end of the rule is then quite straightforward. You seem to be describing holding the rule in mid-air as close to the chain as possible, but without holding or touching the chain and without keeping the chain and rule pressed against each other.
Sweep wrote: 30 Nov 2022, 4:14pm Do you recommend any patricular checker?
In your shoes I would either buy a 12" steel rule, or a cheap digital caliper*, and compare the results from them with the KMC and Park Tool measurers. The latter type of tool is often reckoned to over-estimate total chain wear because it includes roller wear. Measuring the distance between pins with a steel rule or using a digital caliper to subtract roller wear from the chain wear measurement might tell you that you are replacing chains sooner than necessary.

* Brucey's method of 'unequivocal chain wear measurement' using a digital caliper explained here - viewtopic.php?t=115336
ANTONISH
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Re: Chainring teeth?

Post by ANTONISH »

I've got a "chain checker" which is OK - but I find using a steel rule is quick and effective.
DaveReading
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Re: Chainring teeth?

Post by DaveReading »

Pebble wrote: 30 Nov 2022, 12:15am
Steve O'C wrote: 29 Nov 2022, 11:12pm
All this is common knowledge and my only point here is that I would not dismiss a shop or mechanic who referred to chain wear as "Stretch" as being incompetent.
Steve
If it is coming from a bike mechanic then I would.
By that token, the entire civil aerospace industry must be incompetent. Most aircraft designs are "stretched" during their lifetime.
wirral_cyclist
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Re: Chainring teeth?

Post by wirral_cyclist »

When using a steel rule just put a thumbnail at mid pin point pressing into the chainring (or sprocket) and ruler tensioned against your nail, then observe pin near (hopefuly very near) the 12" mark, if you think it is stretched just take it off and double check with chain dangling from a nail, if too long ditch it, if OK clean and re-use.
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Cugel
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Re: Chainring teeth?

Post by Cugel »

Sweep wrote: 30 Nov 2022, 4:14pm
Cugel wrote: 30 Nov 2022, 8:39am

You'd need to be a super-robot to hold a steel rule steadily enough and then view its reading accurately enough (without parallax errors) to make such a measurement. A good vernier will do the job, though - if it really is a good one. The cheap ones are useful for comparative measurements but can be inaccurate for absolute measurements, as needed with testing a chain for wear.

There are good quality chain "stretch" testing tools of the "drops through the links or doesn't" kind. Look for those that claim to have been CNC cut to a fine tolerance. They tend to cost more than the two quid versions stamped out of a plate.


Cugel
Must admit I have always been a bit wary of my ability to pull off the steel-rule method, though I know it's favoured by many of the old pros on here, and maybe was also by brucey.
Do you recommend any patricular checker?
I run nothing above 9 speed and use two "drop-in" checkers.
Park CC-3 with 0.75 and 1.0 marks
A KMC thing with a single "drop-in" prong marked as 0.8

I change the chains when the KMC drops in.
I can't recommend it 'cos I've not got and used one but this looks like it's a well made 'un for not that much:

https://www.amazon.co.uk/gp/product/B07 ... 1UFC&psc=1

Have a look at the close-ups of the various pics.

The fact that it measures a mere 0.5mm "stretch" is interesting. Using that as the change indicator might cost a few more chain pound coins but it'll cost an awful lot less in chainring and cassette £50 notes.

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
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Sweep
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Re: Chainring teeth?

Post by Sweep »

Cugel wrote: 2 Dec 2022, 6:33pm
Sweep wrote: 30 Nov 2022, 4:14pm
Cugel wrote: 30 Nov 2022, 8:39am

You'd need to be a super-robot to hold a steel rule steadily enough and then view its reading accurately enough (without parallax errors) to make such a measurement. A good vernier will do the job, though - if it really is a good one. The cheap ones are useful for comparative measurements but can be inaccurate for absolute measurements, as needed with testing a chain for wear.

There are good quality chain "stretch" testing tools of the "drops through the links or doesn't" kind. Look for those that claim to have been CNC cut to a fine tolerance. They tend to cost more than the two quid versions stamped out of a plate.


Cugel
Must admit I have always been a bit wary of my ability to pull off the steel-rule method, though I know it's favoured by many of the old pros on here, and maybe was also by brucey.
Do you recommend any patricular checker?
I run nothing above 9 speed and use two "drop-in" checkers.
Park CC-3 with 0.75 and 1.0 marks
A KMC thing with a single "drop-in" prong marked as 0.8

I change the chains when the KMC drops in.
I can't recommend it 'cos I've not got and used one but this looks like it's a well made 'un for not that much:

https://www.amazon.co.uk/gp/product/B07 ... 1UFC&psc=1

Have a look at the close-ups of the various pics.

The fact that it measures a mere 0.5mm "stretch" is interesting. Using that as the change indicator might cost a few more chain pound coins but it'll cost an awful lot less in chainring and cassette £50 notes.

Cugel
Thanks, but what do you use now?
That looks good, or at least the write-up blurb seems convincing, but not sure that it provides more than my current Park/KMC pairing.
Sweep
slowster
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Re: Chainring teeth?

Post by slowster »

With regard to the issue of the various specific chain wear measurers providing an inaccurate measurement because they include roller wear, the short lengths of these tools increases their inacurracy due to this error.

The tool in Cugel's link measures wear over 5 links = 5 inches = 127mm. For that length 0.75% wear corresponds to 0.95mm.

I have a 10 speed chain which I recently took off a bike when it had 0.75% wear measured using Brucey's method with a digital caliper to deduct roller wear from the measurement. The roller wear itself on that chain is 0.4mm, i.e. the amount by which the gap between rollers has increased.

If a chain wear measuring tool includes roller wear in the measurement, then the shorter the length of chain measured, the larger the error will be as a result of the measurement including roller wear. I think these tools may over-estimate chain wear by as much as 30% or even more.
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Cugel
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Re: Chainring teeth?

Post by Cugel »

Sweep wrote: 2 Dec 2022, 7:27pm
Cugel wrote: 2 Dec 2022, 6:33pm
Sweep wrote: 30 Nov 2022, 4:14pm
Must admit I have always been a bit wary of my ability to pull off the steel-rule method, though I know it's favoured by many of the old pros on here, and maybe was also by brucey.
Do you recommend any patricular checker?
I run nothing above 9 speed and use two "drop-in" checkers.
Park CC-3 with 0.75 and 1.0 marks
A KMC thing with a single "drop-in" prong marked as 0.8

I change the chains when the KMC drops in.
I can't recommend it 'cos I've not got and used one but this looks like it's a well made 'un for not that much:

https://www.amazon.co.uk/gp/product/B07 ... 1UFC&psc=1

Have a look at the close-ups of the various pics.

The fact that it measures a mere 0.5mm "stretch" is interesting. Using that as the change indicator might cost a few more chain pound coins but it'll cost an awful lot less in chainring and cassette £50 notes.

Cugel
Thanks, but what do you use now?
That looks good, or at least the write-up blurb seems convincing, but not sure that it provides more than my current Park/KMC pairing.
At present I use a Park Tools item:

https://www.amazon.co.uk/Park-Tool-CC-2 ... B000OZFILW

They seem hard to come by at the moment. I can't recall what I paid for it but it was more than that t'other 'un.

Cugel
“Practical men who believe themselves to be quite exempt from any intellectual influence are usually the slaves of some defunct economist”.
John Maynard Keynes
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531colin
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Re: Chainring teeth?

Post by 531colin »

Chain and sprocket wear is an old chestnut which crops up time after time.
For me, the pivotal thing is convenience. I use a Rohloff gauge which is one of the ones you just drop onto the chain, its a "pass/fail" gauge, it either drops down or it doesn't.
I accept that it "fails" chains before it really needs to do so, because it includes roller wear.
However, because I can just drop it onto the chain and get a reading, I check the chain regularly through the winter, in the freezing shed in poor light.
If I had to clean the chain, or put the bike on the stand, or arrange some lighting so that I can see properly, in order to measure the wear "accurately" then I wouldn't check the chain anything like as often, and that could wreck the drivetrain.
Have a look here at a cassette which lasted......viewtopic.php?t=116834&hilit=reverse+we ... e&start=45
James Up Hill
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Joined: 7 Oct 2019, 12:39pm

Re: Chainring teeth?

Post by James Up Hill »

Jupestar wrote: 30 Nov 2022, 1:32pm You say the chain snapped, which suggests there was something wrong with it or fitted badly.

For a chain to snap after 1500 miles is very unlikely to be due to wear.

It may have been stretched as well, but they are two different things..
Thanks. It was fitted by Mr Decathlon's factory; I've never much liked the way it changed over the cassette, a bit gritty - even the first time I rode it. A new chain is £20; that's less than two cocktails in London.

Do I clean the chain monthly? No. Oil it every week or two though, and do try to give it a wipe if I've been out in the rain though I don't always.
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531colin
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Location: North Yorkshire

Re: Chainring teeth?

Post by 531colin »

James Up Hill wrote: 9 Dec 2022, 6:03pm
Jupestar wrote: 30 Nov 2022, 1:32pm You say the chain snapped, which suggests there was something wrong with it or fitted badly.

For a chain to snap after 1500 miles is very unlikely to be due to wear.

It may have been stretched as well, but they are two different things..
Thanks. It was fitted by Mr Decathlon's factory; I've never much liked the way it changed over the cassette, a bit gritty - even the first time I rode it. A new chain is £20; that's less than two cocktails in London.

Do I clean the chain monthly? No. Oil it every week or two though, and do try to give it a wipe if I've been out in the rain though I don't always.
You fitted a new chain and it all works.
This shows that the cassette teeth aren't significantly worn, because significantly worn cassettes with a new chain get "chain skip".
The cassette teeth wear before the chainring teeth, so alls well.

The link in my previous post shows just how long you can keep a cassette going if you change every chain before its gets so worn that it wrecks the cassette.
esasjl
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Joined: 18 Feb 2021, 9:02pm

Re: Chainring teeth?

Post by esasjl »

This seems a good resource for chain wear.
http://pardo.net/bike/pic/fail-004/000.html

Park CC4 should be accurate?
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