SoSmellyAir

During a ride yesterday afternoon, I sprinted a little bit on a flat road, heard a "prang" sound, and felt my chain slip over the rear cog every few revolutions when I pedaled hard. I knew my chain was not worn because I had just cleaned it, measured it with a Pedro chain checker (Chain Checker Plus II » Pedro's NA), and lubed it the day before yesterday. When I got home, I discovered a broken link in my chain. I am quite sure that there are < 2,000 miles on this chain so I don't know how this could have happened. And no, I am not powerful. Luckily, I have an Ultegra chain bought during Thanksgiving sale, so that went on today.

Sy Reene

Did you consider just fixing with a quicklink? Also, supposedly the 105 (601) chain is directional. I'm not sure exactly how one tells if the chain is installed in the right direction, but here's a snip of a 105 chain -- I don't see any of the same markings on your chain.

Mojo31

Markings go on the outside.

eduskator

2000 miles is not that much if it was maintained properly throughout its life. If it was mine, I would get a new link and keep it if it's still good (under 0.5% of stretch).

A chain is as strong as its weakest link, as they say

On a similar note, do you always keep your chain as dirty as that? Looking from the picture, there is way too much lube on it. It will only attract dirt that will end up inside the rollers and reduce its lifespan.

walnutz

If that’s an extremely dirty chain, I’m in trouble 😮. As for OP, that is a really bizarre failure, glad it didn’t cause any major issues.

Sy Reene

Ok.. but which way is up? just curious

Mojo31

Letters are right side up on the top and upside down on the bottom. Duh....

Iride01 

So you are just bragging that you broke the chain........... SH!

Iride01 

No, the plates on most don't care whether they are up or down. Just which side they are on. I've got both upside down and right-side up SHIMANO on the outside plates of my chains.

Moe Zhoost

You think that chain is dirty? You must be one of those waxers. Thankfully I was able to break that habit a decade ago.

Mojo31

I know, perhaps I should have used the sarcasm emoji.

Of course, the plates will be both upside down and right side up no matter how you install it. Just depends on the part of the chain you look at.

Sy Reene

hmm. which letters? See the photo I posted?

Sy Reene

So, by "directional chain", the direction is just that letters are outside, not actually which direction the chain runs in?

Mojo31

See post 11.

Mojo31

Yes.

Iride01 

Oh....

You'd think they would put them on all the same way. If my wife was to ever notice that, it'd drive her nuts. She's a little particular about how things are arranged. If I turn one of the Kurig pods upside down in her pod holder, she gets bothered. <grin> LOL I don't use Kurig pods. Those pods have to be filling up landfills quicker than plastic bottles now. I just brew my coffee in the morning and let it sit in a pot till gone.

79pmooney

+1 My chains are only occasionally that clean. (Perhaps the requirement for clean is higher with higher than 9-speed. I wouldn't know.)

I see chain cleanliness as a balancing act between looks, chain life, land fill and solvent use, my time and my pocketbook. My chains being fairly cheap, doing a lot of work for a few extra miles doesn't seem worthwhile and I have no OCD requiring my chains to be spotless. That might change when I go 11-speed.

Sy Reene

Got it.
Back to the OP.. Is this a 105 chain in the first place? I don't recognize the markings, but perhaps there's OEM versions that differ from retail packaged chains?

looking closely, his chain appears to have an NE engraved in the side plates.

79pmooney

[/QUOTE]
I see why the lettering must be on the outside. Notice the very tidy recess for the pin head on the outside and the simple exposed peened pin on the inside? These chains have vanity issues. Showing off what is never intended to be seen doing something as public as a sprint? He/she couldn't take it. (If the chain was inanimate, it wouldn't care.)

Iride01 

I don't know that Shimano makes any chains that are worried about their direction of rotation. Shimano for a long time has cared that their name is on the outside. Whether that is for advertising or that the side plates are different for the dynamics of upshifting vs downshifting I don't know. I'm happy to oblige them either way.

msu2001la

The side plates are slightly different on the outside vs inside. If you look carefully at the edges of the plates, they have a slight chamfer around the outside perimeter.

I think this is to improve front chainring shift performance. I have no idea why they don't just make both sides like this, but the difference is highlighted in the manual (yes, there is a manual on chains):
Shimano Chains

eduskator

I am not, even if it's the best lubricant out there. My chain, chainrings and cassette are always 100% clean though. All you need to do is wipe it off after every ride. Literally takes 15 seconds.

Psimet2001 

They make them like that because of all of the ramps and features they have worked into the cogs and the chainrings to help with shifting. One set of plates is designed to work better climbing up the cogs. The other side plates are better at climbing the chainrings.

As for it making a difference - It has absolutely made a difference on more than one bike I have worked on where the owner put a new chain on "backwards" then rode it for a couple of hundred miles and brought it in because it shifted horribly.

OP - as for the plate cracking - that's not exactly completely unheard of. It could just be a one off issue. Inspect the other links for cracks that radiate out from the pin. If you cleaning techniques uses cleaners that can cause hydrogen embrittlement then this can happen more easily. There was a bit of a hubbabaloo about using simple green to clean chains many years back and how it's use, possibly in a ultrasonic cleaner or heated wash could accelerate conditions for hydrogen embrittlement to occur.

Psimet2001 

If the general state of bikes that come to me for service are any indicator you are truly wizzing into the wind on this one. Honestly I'd settle for people just washing their bike once every 50 rides or so. Not many do.

SoSmellyAir

The OEM chain was not maintained properly throughout the first half of its mileage. Even though my bike is 4 years old, I did not really care or learn about maintenance until about a year and a half ago. So since I had a replacement chain, I figured I might as well use it, to minimize the chances of the same thing happening.

The photo was taken after a 20 mile ride after a chain cleaning and lubrication. I was doing the post ride wipe, which I generally only do after the first ride after a chain cleaning and lubrication, when I discovered the broken link. Thank you to walnutz, 79pmooney, and Moe Zhoost for affirming the adequacy of my chain cleanliness.