Why exactly is my new KMC joiner link non reusable?

uart
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Why exactly is my new KMC joiner link non reusable?

Postby uart » Sat Jun 02, 2018 1:59 pm

I've just bought a couple of new KMC chains, and the packaging on the included joiner link (missing link) is at pains to point out that they are "non reusable".

Having just successfully clipped them together and popped them apart (twice) to see how they work, I'm wondering why exactly they are non reusable.

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Duck!
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Re: Why exactly is my new KMC joiner link non reusable?

Postby Duck! » Sat Jun 02, 2018 2:02 pm

Because opening them wears down the locking nodes, which then makes a less secure join and increased risk of popping open.
I had a thought, but it got run over as it crossed my mind.

uart
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Re: Why exactly is my new KMC joiner link non reusable?

Postby uart » Sat Jun 02, 2018 2:13 pm

Duck! wrote:Because opening them wears down the locking nodes, which then makes a less secure join and increased risk of popping open.

Ok thanks, that's kind of what I was thinking.

Trust me though, they where still plenty stiff to pop open even on the second try, so I think a limited amount of reuse is going to work just fine.

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queequeg
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Re: Why exactly is my new KMC joiner link non reusable?

Postby queequeg » Sat Jun 02, 2018 2:31 pm

uart wrote:I've just bought a couple of new KMC chains, and the packaging on the included joiner link (missing link) is at pains to point out that they are "non reusable".

Having just successfully clipped them together and popped them apart (twice) to see how they work, I'm wondering why exactly they are non reusable.


You may reuse them on the chain you have installed them on. You should not take a used link and put it on another chain.
'11 Lynskey Cooper CX, '00 Hillbrick Steel Racing (Total Rebuild '10), '15 Cervelo S5

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Tim
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Re: Why exactly is my new KMC joiner link non reusable?

Postby Tim » Sat Jun 02, 2018 2:46 pm

queequeg wrote:You may reuse them on the chain you have installed them on. You should not take a used link and put it on another chain.


Not sure this is absolutely correct but it's what I do.
Each chain comes off the bike at 1000km intervals on rotation with another chain. Each chain is removed and then refitted 5 times ie. each chain and link lasts me 5000km's.
No problems so far.
10 speed KMC links are reusable, 11 speed non.

Pinch the side plates together (inwards) with your fingers and then open them with the tool (whilst still pinching). The pinching loosens the connection and the link opens easier.

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queequeg
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Re: Why exactly is my new KMC joiner link non reusable?

Postby queequeg » Sat Jun 02, 2018 4:20 pm

Tim wrote:
queequeg wrote:You may reuse them on the chain you have installed them on. You should not take a used link and put it on another chain.


Not sure this is absolutely correct but it's what I do.
Each chain comes off the bike at 1000km intervals on rotation with another chain. Each chain is removed and then refitted 5 times ie. each chain and link lasts me 5000km's.
No problems so far.
10 speed KMC links are reusable, 11 speed non.

Pinch the side plates together (inwards) with your fingers and then open them with the tool (whilst still pinching). The pinching loosens the connection and the link opens easier.


Straight from the KMC Site: "Always use a new Missing Link when fitting a new chain".

As for whether they are reusable on the same chain in the meantime, their official position is no, and you may or may not be able to get the link off with just your hands out on the road. However, as long as the link is not damaged, and you don't carry an old link across to a new chain, you should be ok. It would also depend how often you are taking your chain off, but given the cost of the Missing Links, I don't make a habit of just putting a new one on for the sake of it, but I do check it carefully as a poorly fitting link is likely to result in a broken chain.
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RonK
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Re: Why exactly is my new KMC joiner link non reusable?

Postby RonK » Sat Jun 02, 2018 4:24 pm

queequeg wrote:
uart wrote:I've just bought a couple of new KMC chains, and the packaging on the included joiner link (missing link) is at pains to point out that they are "non reusable".

Having just successfully clipped them together and popped them apart (twice) to see how they work, I'm wondering why exactly they are non reusable.


You may reuse them on the chain you have installed them on. You should not take a used link and put it on another chain.

Yes, that is how I choose to interpret for Sram Powerlock links too.
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Re: Why exactly is my new KMC joiner link non reusable?

Postby Duck! » Sat Jun 02, 2018 6:05 pm

RonK wrote:
queequeg wrote:
uart wrote:I've just bought a couple of new KMC chains, and the packaging on the included joiner link (missing link) is at pains to point out that they are "non reusable".

Having just successfully clipped them together and popped them apart (twice) to see how they work, I'm wondering why exactly they are non reusable.


You may reuse them on the chain you have installed them on. You should not take a used link and put it on another chain.

Yes, that is how I choose to interpret for Sram Powerlock links too.

SRAM's wording is quite clear - the link is not intended to be undone. 8 & 9-sp. links are intended to be used several times over the life of one chain, 10+ are not. KMC do both multi-use (which like SRAM 8 &9) are to be discarded when the chain is done, and single use which are exactly that.

Even if they don't fail, repeatedly opening and closing the link increases wear on the link, so you end up with that link longer than every other link in the chain, which leads to rough running, which you'll feel as a bump or clunk in the drivetrain every time the link goes around the cassette.
I had a thought, but it got run over as it crossed my mind.

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foo on patrol
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Re: Why exactly is my new KMC joiner link non reusable?

Postby foo on patrol » Sun Jun 03, 2018 11:01 am

Never had a problem reusing the links and that's with different chains. :?

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uart
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Re: Why exactly is my new KMC joiner link non reusable?

Postby uart » Sun Jun 03, 2018 9:32 pm

Duck! wrote:Even if they don't fail, repeatedly opening and closing the link increases wear on the link, so you end up with that link longer than every other link in the chain


I accept that they might get slightly looser to fit with repeated opening and closing, but I do doubt that it would have any significant effect on the link's length.

To increase the effective length of the link you would need to wear the end stop position of the slot in the side wall of the link. Any effect on the length of the slot from opening and closing is going to be totally negligible compared to when the chain is in use with your full weight on it.

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eeksll
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Re: Why exactly is my new KMC joiner link non reusable?

Postby eeksll » Sun Jun 03, 2018 9:57 pm

i use both 9,10 and 11 speed links.

on both the 9 and 10 speed chians, on my parktool go/no go ruler, when the link is part of the measurement, it registers as "worn" before the rest of the chain. I don't remove my links often, maybe twice in the chain life.

Both my current 9 and 10 speed chains are at this point, 0.5 almost falls in for the rest of the chain, but falls in easily when the chain link is in the middle. I haven't opened the link from new on these 2 chains.

the 11 speed is campag and parts are expensive so I don't let the chain get too worn before swapping.

edit: i use new links with new chains and I also don't notice anything odd with this longer link.

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Duck!
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Re: Why exactly is my new KMC joiner link non reusable?

Postby Duck! » Sun Jun 03, 2018 10:43 pm

eeksll wrote:on both the 9 and 10 speed chians, on my parktool go/no go ruler, when the link is part of the measurement, it registers as "worn" before the rest of the chain.

I have also observed this, on several brands of links, so it's not an isolated occurrence. I was first alerted to joining link wear with Shimano's early quick links (which were pretty dreadful to be blunt), introduced with the 7900-series Dura-Ace 10-sp. chain; I had a customer complain of a weird clunk in the drivetrain, out of synch with the crank rotation. After much test riding, head scratching & investigating I thought to measure chain wear at different points of the chain, with and without the joiner in the measured span. Sure enough, measuring the chain excluding the joining link showed a very healthy chain. Spin around & include the link in the measured span, and it showed as badly worn. That's a hell of a lot of wear in one link! Now those Shimano links were considerably worse than other joiners, but I've observed the same accelerated wear in every other brand of quick joining link I've worked with to some degree. Even on links that have never been opened.

So from my observations, I conclude that, even if manufacturers suggest it's OK with some models, joining links should not be used for the whole life of one chain .
I had a thought, but it got run over as it crossed my mind.

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Tim
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Re: Why exactly is my new KMC joiner link non reusable?

Postby Tim » Mon Jun 04, 2018 7:29 am

11 speed KMC Missing Links are expensive from the usual local and O/S suppliers.
I've bought them at around half the price from eBay, Taiwan source (I think) and they have been genuine parts (I think and hope).
Been using them for 2-3 years and no problems.

Re the above photo instructions.
9 and 10 speed (KMC) can be opened by hand. As I mentioned earlier, pinch the side plates together and they'll disassemble fairly easily without a tool.
11 speed snap closed and need a tool to open. It still helps pinching the plates first.

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Re: Why exactly is my new KMC joiner link non reusable?

Postby eeksll » Mon Jun 04, 2018 9:43 pm

Tim wrote:11 speed KMC Missing Links are expensive from the usual local and O/S suppliers.
I've bought them at around half the price from eBay, Taiwan source (I think) and they have been genuine parts (I think and hope).
Been using them for 2-3 years and no problems.


I got mine off ebay as well.

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