Cycling UK Forum

Sram PG 830, minimal mileage since fitted end July, have even walked any steep bit's over summer, only had a few days only had a few days loaded with camping gear, chain never been exposed to a heavy load, excess stress, salty roads

Several Hr's giving Bicycle absolute post summer overhaul, Saturday. Chain cleaned, merely by soaking in boiled water, c/w washing up liquid & a thorough, link by link wipe afterwards. Only had 2.75 miles, flat road / former rail track, slow speed, intended Sunday half speed, 15-10 mile spin. Took 1-2 rotations of drive train on a slight gradient & chain had absolutely snapped, pin & side plates, bent right of shape. Can cleaning a chain weaken it ? Had flat top rail bridge, flat bit of stone, then a cyclist with chain tool, for repair

Perfect location, routinely walk it evenings, though pigs in field had to miss out on Sunday lunch, opted not to have another mile down the road (Nb. Weeks flabby apples, couple of pears, cauliflower stalk, soggy salad potato, they seem to enjoy it, no room for compost heap)

gbnz wrote: ↑7 Oct 2024, 9:57am ...
Chain cleaned, merely by soaking in boiled water, c/w washing up liquid & a thorough, link by link wipe afterwards.
...

Do you apply anything after that?

Jonathan

Was it the joining link? If so, perhaps only one side had not been fully mated, and so this was the failure point. Easy enough to do if working where you cannot see clearly.

gbnz wrote: ↑7 Oct 2024, 9:57am Chain cleaned, merely by soaking in boiled water, c/w washing up liquid & a thorough, link by link wipe afterwards.

Sounds like you painstakingly eliminated any trace of lube and didn't replace it.

I only found out recently that there,s a right and wrong way to fit a quick link.Also some quick links are only meant for one use ?...Did the chain break at a quick link? How worn was the chain?This can be determined on a clean chain by measuring a foot and see how much stretch there is.Google for details.Very occasionally this happens through no particular reason that you can find.

In retrospect, my error, NO lubricant will have been the reason . Wouldn't have remotely done even a 10 mile ride without a chain lubricated, but as a few Hr's detailed overhaul work required indoors, wished to leave it absolutely clean, hadn't remotely thought a "non ride" an issue

50% long, gradual downhill no pedalling required, 25% short steep uphill would have walked for views, 25% on flat occasional turn of pedal. Not a ride as such, a 16 mile version of an evening walk, incredible landscape, constructions, wildlife. A ride where 6-8mph on the flat would be ok

Naturally had assumed the quick link, no issue with quick link, a NO lubricant issue. Have never tried it cycling without lubricant, would have thought a chain would do miles, sans lubricant, without an issue

Cleaning the chain with water and washing up liquid shouldn't have weaken it. Was you boiling the water with the chain in it for some time, causing expansion of the side plates and loosen the pin?

Sans lube is not advisable but I wouldn't have thought that ~3 miles without it would have caused a failure in the absence of anything else.

Have you done anything to the chain before. Pressed in a pin perhaps? A stiff link that went unnoticed during the post-clean inspection?

Thanks, hadn't actually "boiled" the chain. Hmm, yes, although the chain had 24 Hr's to cool down post clean with boiling water, hadn't considered the fact that an expansion & contraction of metals whilst in water just boiled, could well have caused the issue (Nb. Will definitely clean in future, without boiling water ). Snapped chain must have been linked to cleaning method, snapped within 100' on slightest of gradients, though additional issues with chain occasionally, violently jumping, due to adjustment issue, new Rr derailleur, may be an issue

And no, chain was relatively new, good quality, never had a stiff link (Nb. Looks like new, hate to dispose of stuff, but risk of a snapped chain from dozens of other links, miles from home, too high (Nb. Will definitely start carrying the chain tool as routine, had only stopped, now having used quick links for 14yr's +)

Boiling water won't help - could easily cause different expansion across the rollers, pins and side plates and potential weakening.

Washing up liquid contains ionic surfactants - basically salt - and is also rubbish at actually cleaning a chain, use proper degreaser.

Lack of lube won't have helped but is unlikely to be a problem - you only have to look at half the bikes being ridden around to see rusted squeaky chains in evidence and they kind of survive.

Joining it properly is key, any weakness there or an improperly connected link will be a near instant source of failure.

And a poorly adjusted drivetrain is only going to exacerbate any issues. Fix and clean and adjust the mechs properly.

It is human nature to blame events immediately prior for any breakage but very often the part was already cracked, already doomed, and all that happened was the coup de grace was administered. So any talk along the lines of 'a pothole broke my spoke' is invariably utter nonsense; that spoke, being cracked, was as good as broken anyway. The vast majority of chain failures are like this too.

Modern chains are usually chock full of stress already (eg. from bullseye riveting) so don't need much excuse to break anyway. IMV immersion in boiling water is extremely unlikely to break a chain, since this would require harmful stresses that could only arise if the pins heat up faster than the sideplates. This is just about possible if the chain is placed in very shallow water or directly onto a hotplate, but not otherwise.

So my advice would be to carefully examine the break, looking for signs of prior cracking. The chances are that your chain was already cracked, long before it broke; if so, the true culprit is whatever caused the cracks to start, not finish.

Thanks, no cracks apparent, pin had simply pulled out on one side, the side plate being bent around by a few mm's. May keep the chain in use as it's virtually new, minimal mileage. 12yr's back of whatever, simply used to push pins in to save cost of quick links / won't have heard of quick links for years. Can't recall ever having an issue with a chain snapping after pushing a pin back in

gbnz wrote: ↑7 Oct 2024, 4:07pm Thanks, no cracks apparent, pin had simply pulled out on one side, the side plate being bent around by a few mm's. May keep the chain in use as it's virtually new, minimal mileage. 12yr's back of whatever, simply used to push pins in to save cost of quick links / won't have heard of quick links for years. Can't recall ever having an issue with a chain snapping after pushing a pin back in

Most modern chains are not designed to be joined by pins. Use the proper quick link for that chain (they can vary between chain brands). It's worth having a couple of spares as well.

Much as I was willing to give the cleaning method a bit of blame for the split, it was always almost certain to be the joining of it that was at fault. Sad to say, user error.

rareposter wrote: ↑7 Oct 2024, 4:13pm

gbnz wrote: ↑7 Oct 2024, 4:07pm Thanks, no cracks apparent, pin had simply pulled out on one side, the side plate being bent around by a few mm's. May keep the chain in use as it's virtually new, minimal mileage. 12yr's back of whatever, simply used to push pins in to save cost of quick links / won't have heard of quick links for years. Can't recall ever having an issue with a chain snapping after pushing a pin back in

Most modern chains are not designed to be joined by pins. Use the proper quick link for that chain (they can vary between chain brands). It's worth having a couple of spares as well.

Much as I was willing to give the cleaning method a bit of blame for the split, it was always almost certain to be the joining of it that was at fault. Sad to say, user error.

No, the chain was joined via a wipperman connex quick link. Have used quick links for 12yr's, the pin which pulled out, had never been touched by myself. Merely years ago, used to join chains with a chain tool, pushing pins out, pushing the pin back in.

Fair enough.

There's one more possibility which hasn't been mentioned.
Counterfeit chain.

Shimano in particular have been plagued by this; the likes of Amazon and similar online retailers are riddled with fake Shimano stuff and I assume fake SRAM gear too.

Independent testing on genuine vs counterfeit chains has shown the fake ones are abysmal, they fail all the strength and durability tests.

I would never buy a chain from anywhere other than a reputable bike shop.

Also, I'd be tempted to just bin that one. If it failed at a point you haven't touched then you'll never have any confidence in it. Either:
it's counterfeit and therefore terrible
it's genuine but faulty
the cleaning you did to it has weakened it
In any of those scenarios, you don't want to be putting your weight through it up a steep hill or pulling out of a junction. Bin it, get a new chain from a reputable shop.

gbnz wrote: ↑7 Oct 2024, 4:07pm.... no cracks apparent, pin had simply pulled out on one side, the side plate being bent around by a few mm's. ....

so in your case nothing broke, but a previously untouched pin came out? In all modern cycle chain designs, something is done to the rivet (pin) after it is inserted to make sure it doesn't come out again. Needless to say, but they don't always get this right. For a very long time sedis/sachs/sram used rollers to make their pin ends sightly mushroomed, hence the two lines seen on the pin ends in many of their older designs. However, this approach requires that the pins protrude slightly, so it cannot be used in state of the art chains, most of which have flush pins. These pins are given a different treatment eg. 'bullseye riveting'.

If this is overdone, the chain is chock full of residual stresses, and may crack (if it hasn't already). If this is consistently underdone (which should be detected by QA testing) then the pin pushout force (PPF) is reduced, leaving the chain vulnerable to damage, eg. spontaneously or via a mis-shift.

Using an ordinary chain tool to push an ordinary pin back in always reduces the PPF value in a modern chain, leaving just that link vulnerable.