Broken Bike Chain?

Yes, broken bike chain is a syndrome and no one is immune. It can happen to you with haste. And sometimes there is no explanation other than shoddy craftsmanship. Most of the time it’s a result of poor care.

With chains doing so much of the work, ie, taking you forward up hills and across the land, they get all of the brunt and no thanks. No one gets off their bike and says, “I am so happy about that chain! It’s allowed me to pedal my bike up to this ridge line. Damn it’s gorgeous up here!”

Usually it goes something more like this: “This is a damn fine bike.” They take a look around and move along with a high level of stoke. Life is good. The chain goes unthanked.



What about when the chain breaks? My breaks have been in places that are exclusively isolated and inconvenient. I have to say that at the moment I was not excited about my relationship with my chain.

Why they break:

You’re asking why this happens. So am I. But I know why. Let’s take a look:

  1. chain needed replacing a long time ago and is structurally unsound to operate
  2. really bad shifting (under load)
  3. Installed by an idiot (someone unqualified)
  4. Manufacturer Defect

1. Chain’s need to be replaced as they are a serious wear item. The chain is an assembly of small parts where metal on metal movement is part of life. As the chain twists and bends laterally and rolls over thousands of rpm’s per ride, it’s exposed to dirt and grime and bad shifts. The plates wear at their carrier pins and develop flex. At a certain point this starts to be measured as “chain stretch.” It’s because now the fittings of plates against pins is super sloppy.

broken chain example 1 & 2
fractured chain plates

Then one day under load you shift and then a plate fractures or peels away from the pin and you have a broken chain. End.

broken chain
example 3 & 4

2. When chains shift from cog to cog or chainring to chainring, the chain flexes in an abrupt way, much like when you’re about to miss an exit on the highway at 80 mph and you go for it. Something that is otherwise straight takes on a temporary sharp bend to go to the next gear. When this action happens under load or hard, fast pedaling (like we see done on e-bikes) the chain wears the pins at an accelerated rate. Now concepts from rule 1 apply.

breaking chain
example 5 – chain plate peeling away; chain are quite strong and for a bit this will actually feel like something is going on with shifting until one makes a solid chain inspection

3. When a chain is installed using a formerly pressed out pin, or if a new pin is improperly installed:

improperly installed chain pin
improperly installed chain pin leads to nearly immediate breakage – repaired by simply replacing the link with a master-link

Sometimes the pin installation isn’t right but seems so close that it requires a trained eye. But generally, using a previously pressed pin is the culprit here.

Each chain pin as little flanges at the end that essentially hold the outer chain plates in place. Once a pin is pressed back out it knocks this flange off one side and once pressed back in there is nothing to retain the outer plate on that side of the pin. Do yourself a favor and replace it with either a masterlink or a new chain pin, depending on what chain you have.

shimano chain pin
shimano chain pins, each for a different speed chain.
sram power link
SRAM master link or power link (black is for 10 speed)

4. Sometimes you’re the victim of poor manufacture. Get to your local shop and talk with them about it. Here’s one:

SRAM XX1 Eagle chain that appears to have had a defective pin, notice how the pin is broken in the middle and the ends are still within the outer plates?



Remedies:

Get a new chain. Sometimes you need new chainrings and cogs as well, depending on how worn things are.

Ridin’ the Train

Get your wrenches ready – to throw at people

At a point in time when there was great poverty and starvation, calamity and horror, the Draisienne was invented. Somehow, the folks in the United States misspelled this so badly it wasn’t even relate-able. It didn’t have pedals. It was around 1812. (Bicycling Science, MIT Press, 18)

Since that time there have been folks like me fixing the offspring of the Draisienne, what has become today’s bicycle. In Europe this is still a respected trade as cycling is very much a part of daily life and critical to getting around. Here in the United States, cycling is primarily a recreational diversion. Although, folks will use them to get around the cities, you won’t see so many of them in use on the country-side. Of course as you drive along the country road you’ll see a few of these machines and their owners dead in the ditches on the shoulder as they’re continually targeted by terrible humans driving automobiles. Some call this “roadkill” when it’s a deer.

So the machine abounds. The bicycle is used worldwide for getting from place to place quicker than walking. It’s a workhorse. To fuel it you need to eat potatoes. But like all machines they break down and cause heartache. This is where we, the mechanics of bicycles, come in. We save the day. We’ve been charged with the safe riding of all cyclists, except those who choose to buy their velo from a department store.

In the US more and more folks are riding bikes as entertainment and means of fitness. It means I’ll always have work. But as long as I work on these machines I will never have a retirement plan, a pension, insurance, or really anything other than a bike and place to lay my head.

“Well you chose that career!” People say. Their rationale is that it’s a high-schoolers job. Have you seen what happens when a high-schooler repairs a bike? Have you seen one of these species fix anything after 2006? I’m having problems with my high-school employees sweeping and staying awake; their brains generally resemble soft oats and their ability to express their thoughts is about as lackluster as the wind tipping an over-flowing garbage can. I do what I do because I’m exceptional at it. I am sought out. Good mechanics fix actual problems. When I go away and pursue a “real job” your bike stops functioning the way it should.

If your bike stops working because your shop’s high-school mechanics can’t fix it you’ll go to the next shop and find other high-school mechanics. You’ll pay real money and come away with more problems. You’ll get over it and repeat the process. And then you’ll mutter, “My old mechanic was an asshole but he sure could fix a bike.” Then you’ll move onto other sports, like curling or something equally inert.