mesasone

On the way to work today, I broke my chain. Just fell off as I was starting from a dead stop at a traffic light. I went back to grabbed the chain and carried my bike to work, and then made the walk of shame home tonight. Was not a happy camper.

I'm not really sure what happened. Aside from the outer plates being bent to hell and an indentation on the inner plates, the link looks fine to my untrained eye.





Anybody seen this before? I am a bit concerned if my chain is failing for no apparent reason.

10 Wheels

That happened to me on my new bike ,when at 200 miles, I was learning to shift going up a hill.

HillRider

What make and "speed" is the chain? Had a pin been removed and the same pin replaced in the past?

bikeman715

just buy a new chain,or buy a link and put the chain back togather.

bikinfool

Carrying a chain tool and a quick link/power link will save you a walk. Looks like something may have gotten jammed in your drivetrain, something as simple as a pebble can do that if it's in the right place at the right time. You might also check your cogs and chainrings for damage.

Joshua A.C. New

Oh, man. All for the want of a chain tool.

mesasone

I actually have a chain tool and usually carry one, but had emptied my saddle bag last weekend and neglected to put it back in there.

As for the chain, it is a 9sp SRAM PC-971. No pins have been removed up until this morning when I removed the broken link.

Joshua A.C. New

Yeah. I know that one. I also only get flats when I've neglected to bring my inflator. Also, it rains when I've forgotten to put my mudguard back on.

Da Tinker

At least one pin had to R/R to mount the chanin on the bike. How much wear is on the chain?

This seems to be a typical failure mode for chains. I perfer to use SRAM or Wipperman links.

masiman

Not if the chain has a SRAM or Wipperman link on it.

bikinfool

? How do you figure?

Da Tinker

The pushed in/out pin is a weak point in the chain. The other pins have been peened or swedged over on the ends to keep the plate from spreading past the end of the pin.

Remember the extra effort it takes to start to push a pin out when you cut a chain? That's the effort needed to overcome the swedging. Out of line forces, such as a present when the chain line is anything other than dead solid perfect, can cause the plates to spread.

mike_s

Uh, he said "it is a 9sp SRAM PC-971," and that no pins had been removed (so none could have been replaced). He is obviously using the SRAM PowerLink which came with the chain.

mesasone

Yep, this chain has a PowerLink on it, which is what I use when I remove my chain.

Da Tinker

Ah, but I did not make that assumption. If that is indeed the case, beats the heck outta me why it at that link. Maybe some past twisting?

mike_s

It's not an assumption. It is the only logically consistent conclusion.

Supertick

I never broke a chain until I went to 9sp. I have broke two 9 spd chains so far. I don't care to start a war here, but I broke both 9 spd chains while powering up a hill on tour. I did not break the chains on the same tour either. Like I said, I never broke a 7-8 spd chain while on tour or any other time. Might just have been my time. I always do regular maintanence on my bikes so the chains were not ignored. Just my opinion!

mo_feezy

This just happened to me on Saturday night as well. Same chain, same bike (assuming it was your lht). I had just had my one month tune up last week and hadn't ridden much due to rain, so I was stoked to be out on a longer ride on sat.
Lbs said they removed a kinked section when it was in, and on sat the chain kept skipping until it finally just popped off. They replaced the chain, so I'm hoping it was just that, but I haven't had a chance to go for a good ride yet due to the weather again.

The guy at the lbs said that from the looks of it, it was a defect.

operator

There's only 3 reasons why a chain should break.

1) Extremely worn
2) Damaged/twisted chain
3) Installation error

By far #3 is the culprit for people who actually maintain their bikes.

LarDasse74

#3 is probably the most common, but there are, as someone mentioned above, ways to damage a perfect chain while riding (shifting under extreme load, chainsuck, debris caught in chain) meaning that @ 2 is very likely as well - probably more likely if there was more than a couple hundred miles on it when it broke.

coldfeet

So, how many miles on it?

operator

This is a worthless metric for chain wear. That's why we have 12" rulers.

Ex Pres 

I've broken a SRAM PC-951 with less than 100mi on it. Same break. I had used the PowerLink and had no reinserted pins.

I was going up the steepest part of a hill that averages 10%. Guess 200# = too much for SRAM.

My LBS gave me a new one no questions. SRAM will stand behind it, but they shouldn't break.

bikinfool

+1

ogbigbird

hmmm... if there was a power link that could be used for chain "breaks", that would almost rule out that someone used a chainbreaker and didn't drive that pin far enough back into the side plate. i've seen that one a few times, and untill you break a chain riding a single speed with full fenders and ONLY a coaster brake going down hill, you haven't lived yet.

perhaps someone took a chain tool to it b4 and didn't drive the link back in symetrically all the way. could be defective. if you don't fully replace it and decide to mend and reuse, inspect the other link pins to be sure they are properly driven in and symetrical.