I did some searching on the forums, and I cannot find anything recent that specifically addresses this. Years ago, I only used Shimano chains, but I got tired of buying their overpriced chain pins, and decided to try SRAM and the quick link. I have put thousands and thousands of miles on SRAM chains and I was totally convinced that they were better chain for the price. I had no issues with them at all.

Recently, however, the SRAM chains have been giving me problems. The last two chains on my MTB have snapped while I was climbing as a result of one of the outer plates slipping over a pin and torquing that link to the breaking point. Has anyone else noticed a decrease in quality of SRAM chains lately, or is this just a coincidence?

I've broken one SRAM chain this year. That's not enough data points to make a determination.

Have you considered using a Shimano chain with a removable link? It seems like people do it quite often. From what I hear Wipperman chains are awesome, but don't have any experience with them at all.

I'll add my data point of no problems.

I've had good luck with SRAM chains but again, obviously not enough data points to matter.

Do you do a lot of shifting under load on your MTB? This can cause premature failure. Tiny MTB granny rings put more tension on a chain than just about any other application. Obviously they should still not break, but if you're hammering on them and "power-shifting" a lot I wouldn't say it's unreasonable. Are your chainrings/cassette badly worn? Again, this won't help.

+1 for using a Shimano chain and SRAM link if you're unhappy with SRAM chains.

I wouldn't say I am putting a ton of force on the chain while shifting. I certainly try not to as much as possible, but in both circumstances the chain did break under load while shifting.

That would be the cause IMHO. Shifting under load puts a lot of stress on the chain. It's best to lay down a couple of power strokes to gain momentum, then lightly pedal as you shift.,,,,BD

I've got thousands of kilometers on both kinds and never had issues. For Shimano chains, just use KMC quick links. Easy.

I use both Shimano and Sram chains and I use Sram quick links on all.

Shifting under load will break a chain. I actually used to be able to break chains on demand as a demonstration for customers, and all I did was shift into the small chainring, hold the rear brake lightly while I shifted back and forth a few times on the rear while pedalling. I had 100% success rate for causing failures.

Edit: I just noticed the OP’s handle is ‘Big_Rider’… I, too, am a ‘big rider,’ and that is why I was able to break chains so consistently. Sorry, big rider, but you are going to have to relax your massive leg muscles when shifting from now on… don’t stop pedalling, just don’t shift while exerting 100% power!

A couple of years back, SRAM recalled 10 spd PowerLocks (one time use masterlink) due to cracks. In the event you have a 10 spd and the masterlink is breaking, that might be the answer. The suspect link had a production code of "M" or "N". See https://www.cyclingnews.com/news/sram...luntary-recall

I've had great results with SRAM for mountain (9 spd) and road (10 spd). I did not like the one-use master link on the 10 spd model, so I switched to KMC. With ~1500 miles on the KMC, I prefer it to the SRAM. Not only does it have a reuseable master link, it shift nice and has performed flawlessly.

I must be a real lightweight weakling as I shift under load all the time on the road and mtbs and have yet to break a chain while shifting. I even shift while standing and pedaling, though not generally at max effort. This is with both Shimano and SRAM chains.

There's a guy who brings a bike into the shop for repair quite often, as he is a big big guy as well. I mean I am 220-230 on average lately, but I have never FOLDED a big chainring like this guy did last time he brought his bike in. He said all I did was jump up on the bike with one foot on the pedal, and used my weight to propel myself from a dead stop. This should give you an idea of what stress a chain is put up against while shifting under heavy load. Go single speed and use a 1/8" chain if you want to mash that hard?,,,,BD

sram chains seem to wear out faster for me.

The single largest cause of the type of failure the OP describes is shifting under load. This twists the chain and forces the plates outward on the pin and will break any chain. It doesn't necessarily break during the shift, but with a plate hanging on the edge it'll break the next time it's heavily loaded.

To prevent this type of failure modern chains (since Hyperglide) have the pins peened over the outer plate forming rivets like those used in bridge construction. This is why they cannot by cut and spliced by simply pushing the rivet back and forth. Once the peened lip (think rivet head) is sheared off pushing the pin through, there's nothing left to prevent plate spread when the pin is pushed back.

Getting back to Sram- Srams chains come in a range of qualities. I suspect that the basic parts are the same differing only in finish, but the biggest difference is the type and extent of peening of the pins, running from 4 points at the lower end, to 100% at the top. The greater the extent of the peen, the greater the resistance to damage from shifting under load.

Note that all chains meet the same standards for break strength under tension, and if not for side stress all would be equally strong.

I'm using a couple of Sram chains, before that one was running a Sachs chain, the old name for Sram. Zero problems. I have had a couple of Shimano failures, pin pulling out of ones side and the link bending or braking.

All of my chains have always been mid-to-high-end Shimanos (HG-73 & HG-93) but I bought a SRAM chain (PC-9**) on the advice of an LBS employee. It worked great and shifted very well for four months and then snapped while climbing some stairs at Butler U. Undaunted, I repaired the chain after a 3 mile walk, and it work just fine for about two more months, until it snapped again going over a 2 ft log on a local trail. That was it. It became a set on chain whips and hasn't given me any problems since.....

Is there an industry standard for bicycle chain, like ISO or ASTM?

I'm sure there is, but don't have the time to pull it up. Years ago, (before ISO for bikes) Any decent 3/32" chain had a tensile breaking load of 1,100 or 1,200kgf. Today there are still chains rated at 1,200-1,300kgf.

With all that reserve strength you'd think chains would never break, and in fact they very rarely do just from tension. As I said earlier, chains break because a plate is forced over the end of the pin. This doesn't reduce the strength by half, but closer to 95 or more percent, because with only one plate the chain is free to bend that plate, allowing the other to slide free of the pin.

That process accounts for just about all the breakage we see, with a small percentage breaking because of a structural defect, or stress crack in a plate.

If you close chains properly, and don't spread the plates by shifting under load, a chain should never break. Consider that we're all riding solo bikes using the same chains as those used by world champion hill climbers using chainrings as small as 24t (mtb). Those same chains are also used as final drive chains on tandems, often with two strong riders, so they obviously have reserve strength well beyond our needs.