Chain wear

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meic
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Re: Chain wear

Postby meic » 9 Jun 2011, 12:42pm

You shouldnt be surprised by the rapid wear rate on your chain.

Hard wear resistant materials tend to be brittle and are not very strong.
So the parts of your chain are made of a strong material which has just a small layer of its surface hardened to resist the wear.
When you break through that surface hardened layer, the soft stuff underneath wears out much faster.
Yma o Hyd

snibgo
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Re: Chain wear

Postby snibgo » 9 Jun 2011, 12:50pm

Dan wrote:This gives 5/1370mm = 0.36%, well over the 0.1% recommended for replacement.

I don't recall seeing 0.1% as the recommended limit.

http://www.sheldonbrown.com/chains.html suggests a wear of less than 1/16" in 12" (which is about 0.5%), then all is well. Double this is too much wear.

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Mick F
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Re: Chain wear

Postby Mick F » 9 Jun 2011, 2:19pm

Dan wrote:Mick F you write
it's perfectly OK to break and re-join Campag chains. Yes, I know the pins are specially shaped and you damage them slightly, but if you're careful to get them back exactly correctly, the chain will have no ill effects.
how did you remove and replace them without causing this damage?
I don't know why you got damage.
I don't damage mine.

I'm not about to fiddle with either of my 10sp Chorus chains, but I'll go out and play with the Campag 9sp chain shortly and see if I can take some photographs. Back soon.
Mick F. Cornwall

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Mick F
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Re: Chain wear

Postby Mick F » 9 Jun 2011, 2:41pm

Here's a pictorial history of a Campag 9sp chain being broken and reassembled.
Chain 1.jpg
Chain 2.jpg
Chain 3.jpg
Chain 4.jpg
Chain 5.jpg
Chain 6.jpg
Chain 7.jpg
All done, but it takes a bit of care to get the pin central and the joint nice and free - but not too much.

As you can see, there was no damage and the joint was made good. I would have no hesitation to breaking and re-joining a chain. Missing Links just make it easy and quick.
Mick F. Cornwall

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[XAP]Bob
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Re: Chain wear

Postby [XAP]Bob » 9 Jun 2011, 3:44pm

Is that a spot of dirt on Mick's chain?

Oh, no - dust on the monitor...
Sorry - scare over ;)

:lol:
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

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Trigger
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Re: Chain wear

Postby Trigger » 9 Jun 2011, 4:07pm

How is it best to avoid stiff links when splitting and rejoining with a tool?

Whenever I do it it never works, even with equal pin showing either side of the outer plates it's still rock solid. I usually end up working it side to side to try and loosen it up but that always feels wrong.

MartinC
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Re: Chain wear

Postby MartinC » 9 Jun 2011, 4:16pm

Trigger wrote:How is it best to avoid stiff links when splitting and rejoining with a tool?

Whenever I do it it never works, even with equal pin showing either side of the outer plates it's still rock solid. I usually end up working it side to side to try and loosen it up but that always feels wrong.


You can't avoid them. You wiggle them form side to side (like you suggest) to loosen them up. Some chain tools have an extra step on them that only supports the "top" sideplates - this allows you to push the pin through them a bit more to loosen it. You can see this in the picture of Mick's chain tool (if my description is good enough!).

niggle
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Re: Chain wear

Postby niggle » 9 Jun 2011, 4:22pm

Dan wrote:I took off my centaur chain and put on a new KMC chain, sadly it skipped on the 11 tooth sprocket under full power. So the centaur is back on this time with a KMC missing link.

When I measured the old centaur chain against the new KMC it had stretched by 5mm over the length of the whole chain. This gives 5/1370mm = 0.36%, well over the 0.1% recommended for replacement.

I am surprised that it went from <0.075%, (using my Rohloff caliber 2 go-no-go chain checker) to this after about 2000km despite cleaning and lubing it weekly and using mudguards through winter.

My next question is should I carry on riding it until it wears out completely, or replace chain and cassette now to protect the chainrings?

On the point about reusing rivets. I took care when using a chain tool to remove the rivets, when I checked the ends of the rivets that I had removed (to remove the chain and fit a KMC missing link) they were seriously damaged, the peened end of one rivet was pulled off entirely, the other had been effaced. There was also some visible distortion of the outer plate around the hole.

Mick F you write
it's perfectly OK to break and re-join Campag chains. Yes, I know the pins are specially shaped and you damage them slightly, but if you're careful to get them back exactly correctly, the chain will have no ill effects.
how did you remove and replace them without causing this damage?

Hi Dan, can I just politely suggest you might be miscalculating by a factor of ten, the Park Tool Chain Wear Indicator is designed to measure at 1% and 0.75%, not 0.1% and 0.075%, so it seems likely that your tool is also calibrated to 1% and 0.75%. The stretch of your KMC chain does indeed work out at 0.36% so it should be fine for a while yet (and if your Rohloff tool did previously measure it at 0.75% this shows the inaccuracy of the chain checker compared with a steel rule, I would suggest due to the reasons I mentioned before).

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Re: Chain wear

Postby BigG » 9 Jun 2011, 5:31pm

Trigger wrote:How is it best to avoid stiff links when splitting and rejoining with a tool?

Whenever I do it it never works, even with equal pin showing either side of the outer plates it's still rock solid. I usually end up working it side to side to try and loosen it up but that always feels wrong.

It is not difficult. Turn the chain over and mount it on the upper lug of the chain tool so that the pressure is taken on the link nearest the screw handle. Then tighten the screw about one quarter of a turn so that the lower outer plate is moved slightly away from the upper outer plate. This is what the upper lugs on the chain tool are provided for.

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Mick F
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Re: Chain wear

Postby Mick F » 9 Jun 2011, 8:21pm

Yep.
That's the way it's done.


[XAP]Bob wrote:Is that a spot of dirt on Mick's chain?

Oh, no - dust on the monitor...
Sorry - scare over ;)

:lol:

This chain hasn't been used for a few years and resides in a box in the workshop.
This chain covered 7,500miles before being relegated to "spare parts" when I went to 10sp.

Sorry, it's a bit cruddy and dirty due to misuse, not use!
Mick F. Cornwall

Dan
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Re: Chain wear

Postby Dan » 11 Jun 2011, 3:00pm

Niggle, you are (nearly) correct, the Rohloff Caliber 2 measures stretch at 0.075 and 0.1 mm PER LINK (according to the instructions), not 0.075% and 0.1% as I mistakenly thought. So I was out by a factor of 1/25.4=0.039

Taking 1 link to be 1 inch (25.4mm) of chain the Rohloff chain checker calibrations of 0.75mm and 0.1mm per link translate to 0.075/25.4x100=0.30% and 0.1/25.4x100=0.39%.

Direct measurement of my old centaur chain against the new KMC showed it had stretched by 5mm over the length of the whole chain. This gives 5/1370mm = 0.36%.

Interesting that this is less than the 0.39 according to the chain checker. Presumably 0.36% is the true figure (unless older chains are more elastic and have to be measured under tension) and the chain checker produces a reading of 0.39% because increased play in the rollers exaggerates the stretch, as Niggle pointed out in an earlier post.

Anyway the chain has stretched enough to have worn my 11 tooth sprocket badly enough that a new chain jumps on it.

Regarding damage to the peening on rivets, here is a link to a bad tempered argument about it http://archive.roadbikereview.com/00/0EFBB3ED.php

And here is a link to some nice pictures on the park tools website showing damage to the peening http://www.parktool.com/blog/repair-help/chain-installation-derailleur-bikes the rivets that I extracted from my campag chain both looked like the images taken in the optical comparator. http://www.parktool.com/uploads/images/blog/repair_help/chain13.jpg

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Mick F
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Re: Chain wear

Postby Mick F » 11 Jun 2011, 9:15pm

Thanks for the info and the photos Dan.

I still stand by what I say.

Do it gently and accurately.
Mick F. Cornwall

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Mick F
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Re: Chain wear

Postby Mick F » 15 Jun 2011, 10:09pm

Just an update on my chains.

I've put Chain B on the bike, and taken off then cleaned and dried Chain A.
Chain B is ready for the rigours of life, whilst A is hung up in the workshop waiting for resurrection 1,000miles later.
Chain A has done 5044miles and ready for a rest, and the new kid on the block - Chain B - has only done a paltry 4003miles.

I'm off on a 1,000mile ride in July, so I will buy a new chain for it, and call it Chain C.
A and B will continue to live and mount up the miles later in the year.
Mick F. Cornwall

LANDSURFER74

Re: Chain wear

Postby LANDSURFER74 » 15 Jun 2011, 10:38pm

Chain wear;
Remove chain.
Wash in pariffin / white sprit or AVTUR F34 / AVCAT F40.
Lay on kitchen table with side plates vertical.
Take each end of chain and try to form a circle.
If a half circle is achived, bin chain.
If not , lube and refit.

In 40 years of cycling i've never had a chain fail.

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Mick F
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Re: Chain wear

Postby Mick F » 16 Jun 2011, 8:28am

LANDSURFER74 wrote:Take each end of chain and try to form a circle.
If a half circle is achived, bin chain.

Why?
Sorry about the focus, but I had to stand on a chair and hold the camera above my head!
You get the picture, anyway.

Why bin a chain when it gets like this? There is ZERO stretch that I can see on it when measured with my 39" rule.
Chain Bend.jpg
Mick F. Cornwall