This weekend, it's kinda mid-season, and the weather was iffy so I pulled the chains off 4 bikes to clean and re-wax. On one, when I pulled the chain out of the wax, one end was hanging low instead of on the usual "dipping loop". Looking closer, at the end, there were two plates -- but no roller between them? I was able to fish the errant roller out of the wax, but presume the chain is toast. Is this a common failure? The chain is a PC-870, not like it's off-brand, perhaps 1000 miles, unsure how many waxings from new. Maybe I over-agitated when swishing the chain around in the hot wax.

it happens... re-install the bushing between the side plates.. it should kinda click in place when you apply a bit of a squeeze to the side plates.

this happens fairly frequently to my chain whip chain end...to prevent that, i put a short piece of a bread sack twis tie wire through it.... not an option for a working chain, but worth mentioning.

a way to prevent it in the future, when you're waxing... use the twist tie wire thing, or put the quick link back in.

IME this indicates that the chain has a pretty fair amount lateral slop, to allow the two inner plates to spread apart enough to lose the roller between. Usually just reinstalling the roller is fine, however I would want to check that chain's wear and shifting feel and if those weren't too good consider replacement. Andy

This happens to me often.

Why not just pop off the outer plates and re-attach with an 8 speed quick link - rather than pushing the pin and roller back in? Or am I missing something?

It doesn't happen to me often, but does rarely when removing a chain for cleaning / waxing. It seems to indicate that the inner plates for the end pair were spread slightly when removing, which can be easy to do if the rivet is pushed by a chain tool instead of popping off a quick link. In every case, if the chain measures OK for overall wear, I just pop it back in and reinstall, with no noticeable bad effects.

If someone plans to periodically remove and reinstall a chain for cleaning / waxing / other reasons, a quick link is a much better solution than using a chain tool, especially for chains with pin widths 7.1 mm or narrower. It's rather easy on 8-9+ speed chains to reinstall the pin in a manner where later failure is possible.

Maybe I should have asked this question, and waited for a response, before I ordered a new chain, arriving today. That said...

... You know, I did notice a bit of lateral flex; and I recently saw there's a measuring tool that not only measures chain linear wear/stretch, but also lateral. Might need to invest in one. BTW this is a 1x7 installation so I guess I need at least some lateral flex.

a proper multi-gear chain NEEDS some side flex, or it won't begin derailling when told to...and having a new chain is always a plus.

i have a chain gauge... somewhere... probably in the "i never use this tool" ammo box with my Park bypass cable destroyers, worn out cone wrenches, and those super thick, super useless, plastic tire irons.

i grab three links, pull, push, pull, and bend/flex to test chains... i test a lot of chains.
I taught someone how to test chains, yesterday.
his chain was thrashed... his gauge said it was fine, lots of life left in it... it squeaked, rattled some, and refused to downshift without a couple-three spins of the cassette... the cassette is also thrashed... after a short instruction, he learned to see that fact in two seconds.
i hear someone sells gauges for that too.

I can supply a new chain for a ride in the ‘64 Tiger

The replacement PC-870 arrived, just cleaned it, waiting for the wax to melt. The new one seems to have the same amount of lateral flex as the old one. Then again,I am only recently using other than 5-speed chains, and 7/8 speed chains always look "loose" to me. BTW, when comparing length, the old chain showed zero linear wear/stretch, so this chain might be newer than I recall (I do not log my miles on each bike).

And, of course, that's how you shorten a chain, and it's the end link of the chain that had the problem, 50% chance the affected link saw a chain breaker. Is there a 21st century way to shorten a chain?

RCMoeur makes some good points about chain removal and reattachment but I have a couple of quibbles.

" It seems to indicate that the inner plates for the end pair were spread slightly when removing, which can be easy to do if the rivet is pushed by a chain tool" This would require quite a miss feat with the chain pin tool during it's use. First the pin acts as an alignment dowl pin, keeping all 4 chain plates in synch WRT to each other. Then as the chain tool pin is pressed through the chain it replaced the link's pin as that alignment device. Remember the tool's pin is slightly smaller in diameter than the link's pin it. The tool's pin will slide in and out of the links freely, unless one lets the tool pin become mushroomed from repeated use, like after a few dozen uses. By the time mechanics have used the tool that many times they really should know how to position the tool pin WRT the link's pin so to reduce the chance of more mushrooming. Also every shop (and some friends I have helped) I have been in knew that the tool pin needed to be "dressed" at its tip periodically, basically a soft rotation against a grinder wheel to restore the tool pin's OEM shape. When pressing the link pin out the second outer and inner link plates are pushed up tight against the tool's "anvil". That second inner plate won't go anywhere except against the second outer plate's inner surface. It might be on removing the tool pin from the link that a badly mushroomed tool pin might catch on the first set side plates. This has happened for me many times. But it's generally easy to overcome this snagging with some twisting about of the tool and chain as one lightly pulls on the tool pin. But this has never happened on the inner plate hole, only the outer plate's hole. Remember that the outer plate's pin hole is a tad smaller in diameter than the inner plate's is (or the chain link would never freely hinge about).

"a quick link is a much better solution than using a chain tool, especially for chains with pin widths 7.1 mm or narrower. It's rather easy on 8-9+ speed chains to reinstall the pin in a manner where later failure is possible." Agreed but I think some more explanation is in order. The reason why reusing a chain pin with most all current (perhaps except 1/8" non derailleur) chains is a bad idea has nothing to do with the chain width but everything to do with the modern indexing shifting compatible chains and their using pins that have been peened/riveted at their very ends to better withstand the prying apart forces a chain will see when being shifted during high power pedaling. (And this is but one reason why learning good shifting techniques is a good idea). The mushroomed over pin end won't be as able to be pulled (or pushed with a tool's pin) through the outer plate's hole. This is what the chain brands call "strength", not the tensile strength of the chain as seen in the lengthwise pulling under pedaling but the resistance of that link pin not sliding out of the plate hole under shifting forces. RCM's sort of suggested this with the reference of "later failure".

Why does this mater to me so much? Because I have seen too many damaged chains from miss handling over my years. With very few exceptions nearly every chain problem is caused by the rider/mechanic. bad attachment method, wrong replacement size, improper length, poor shifting technique (and with the demise of front shifting some of this category will disappear), lack of periodic maintenance (like lubing) and outdoor storage are all some examples of bad things that are not the chain's fault. We all have booboos happen if we ride enough but so many chain problems are so avoidable.

One example of the chain really being the problem is when the side plates are "hardened" too much during manufacturing and have become more brittle than intended. Sedis (before SRAM was a thing) had at least one production run with said bad heat treating. The outer chain plated could start to crack at the pin hole (remember the pin is a press fit here and as such induces expanding forces to the plate hole) and in time the cracks would break through and the pin would pull out. This happened to me on our Burley Duet tandem back in the later 1980s, thankfully only a mile from a LBS that i could buy a chain and cheap tool from to do the on ride repair). There have been a few more brands that have had this brittle side plates problem but none that had the notoriety of the Sedis one. Andy​​​​​​

BTW, is this always true? I was getting ready to break out my over-used micrometer and check that; early-1970's chain breaker versus 2025 chain, did not know if pin diameters have changed.

I do use quick-links on all bikes now, the chain breaker is just used the initial time to set length.

Oh, I guess the chain has cooled now -- time to re-install. Time to go...

Mr. Stewart's response elaborated on what I didn't.

My experience has been that even an long-time mechanic can have the occasional bad rivet-push. The advantage of the experience is recognizing this and addressing it.

From observation, most 5 and 6 speed chains (pin width greater than 7.4 mm) don't use peened pins. It's also very hard to source quick links in sizes wider than 7.3 and smaller than standard singlespeed. So for those chains there's no choice but to reuse the pin and link. Also, peening on 7.3 chains depends on brand and model. You can pop and push Sedisports to your heart's content, but might not work as well on a Uniglide. Below 7.1 mm, it seems they're all peened.

I've seen chains at the co-op that had 3-4 quick links on them. Probably wanted to be sure there wouldn't be problems.

I find that finishing with a vise-grip often gets it right.

The trick I use to ensure the tool's pin is well centered on the link's pin is to only slightly press the pin initially, enough to make it move but not so fat that the tool's pin really enters the link's hole. Then i slightly loosen the tool and reposition the tool's pin while softly retightening it. This will generally allow the tool's pin to become properly centered and not hang up on the link plate hole. This along with a properly "dressed" tool pin end and the chance for tool pin damaging the link plate is greatly reduced. Andy

I have great respect for your feel; I don't have it. When I get to the point that pushing on one side makes it come out imperceptibly (except to flexing the chain) I give up and use a vise-grip, which applies pressure to both sides. Often I can't feel the pin sticking out, just the chain sticking.

Wish I had remembered this -- happened again, different brand chain. Alas, I let the wax cool in the pot while letting the wax on the chains (doing three bikes today), so I need to re-melt and then strain the molten wax. Sheesh!

EDIT: OK, found it, popped back in with a little fiddling, seems OK now. But I need to remember to wire-in the end rollers in the future before waxing!

Why not just use the quick links?

I thought about that; I've read some opinions on not ever using quick links, master links, whatever... more than once. I am doing that anyway, on the bike, would additional "uses" during cleaning/waxing make it more so?

If you remove the chain to clean/lube it and reinstall the connecting link has seen 2 more "uses" One when taken apart and the next on reassembly. Simple math with no assumptions of what's "use".

Now having said that, many people reuse their connecting links a few times over the chain's life with zero issues. Some will have problems (generally the link will self break apart during riding {coasting over bumps as example) but there seems to be few of these incidents compared to the times the reused link holds together just fine. Thankfully loosing a chain when riding usually is not a safety issue (unless you're doing something when a loss of power will be dangerous, like trying to beat out a stop light).

I've "lost" 2 chains on my bikes due to connecting links coming apart. Both times were when coasting and riding over rough road patches. That bike has a fairly high effort freehub, meaning the freehub body won't freewheel as easily as most other brands do (when working well) This slight extra "push" on the chain, from the freehub wanting to continue to rotate when coasting, can push the two halves of the connecting link together enough that with other inputs (rough road) and the pins cab disengage from their slots. Both times I frustratingly just stopped and collected the bits, reinstalled them and road on. Thankfully I was able to find both link halves both times. But for an offroader where the dropped link halves might be lost forever just carry a spare link. Andy

Good advice... I just need to examine and identify exactly which chain is on which bike. Pretty sure at least one bike is running a PC-870, my IGH bike has a Connex of some type (that's the one I had issues with yesterday). At least a spare link does not add much weight to my "kit", which is usually rather minimal.