How often does a coaster brake break?
 

I read on Sheldon Brown's website this could happen, and it did to a friend's kmart bike in kindergarten. But is it likely on a non-junk bike?

I would rate the likelihood of a coaster brake failing as extremely unlikely. I volunteer at a non-profit and have overhauled hundreds of coaster break hubs. Even the cheapest hubs on the lowest end Walmart bikes have very robust builds. They are the one item on BSOs that actually have enough grease.

The most likely ways to damage a CB hub are to burn off the grease by riding in very hilly areas (riding a coaster brake in hilly areas doesn’t sound fun in the first place) and forgetting to connect the reaction arm which would loosen the hub during braking and lead to bearing damage.

Generally by the time your coaster brake breaks the rest of the bike is already making it hard to ride.

The two best ways of killing one is to not maintain it until the sprocket bearing gives up and the internals begin to break up - but the loss of coaster function is a big indicator, or take it to the mountains and wonder why it fades long before a modern disk brake would.

They are easy to rebuild, and it is often cheaper and more effective to replace all the internals if it still fails to engage cleanly after it has been cleaned, greased and adjusted.

We talking' about some unbranded coaster hub out of an unknown factory in China, or a Velosteel or a Monē?

The #1 problem I see is the lack or securing the brake reaction arm. This allows the arm and the connected internal parts to rotate on the axle and cause bearing slop and loss of braking. #2 is not having the cones and lock nuts counter tightened enough to prevent the axle from rotating during securing the axle nuts. Again slop or overly preloaded bearings result. Note that both issues involve the wheel's removal and reinstall by someone who isn't experienced. I have to say around here we nearly never see a lack of lube due to heat. We do see really gummed up old grease sometimes. There was a local bike shop, years ago and long gone, that would do quickie CB overhauls by just loosening up the insides and pouring in a tablespoon or two of kerosene. Much like spraying WD40 into a STI shifter pod this would soften up the gummy grease, at least for a while... Andy

Kmart is the poor man's Wal-Mart

I've had cables break on the best of brakes. But I've never had a brake break. Even on the cheapest of bikes I've owned or bought for my kids.

About the only actual failure I’ve seen on a coaster brake was on an older, high quality unit. It had a circular spring pulling the brake shoes back. This spring had broken.
Then I’ve seen a few with very worn brake shoes.
So I’d say a quality unit, stored reasonably well is very unlikely to break.

If you live in a mountainous area. Going down hill can heat up your coaster brake enough to either fail or seize.

Indeed, when I moved to Madison, I lived on top of a steep hill with a tight turn and busy intersection at the bottom, and my coaster brake faded on that descent. First I thought the hub just needed a repack (they called it "repack" racing for a reason), then on the second time, I realized what was actually happening. Just like we've taught about how to properly descend on a road bike, properly descending on a coaster brake bike is a matter of understanding the physics of what's happening and remembering to make appropriate accommodations. Most importantly, the simple technique of descending slowly reduces the power delivered to the brake and lets it keep up with its own cooling. Also, pulsing the brake lets the oil film recover.

But these days I would not ride a coaster brake bike without a front hand brake. Just a couple days ago, I dropped my chain on an off road trail, and the hand brake was my only practical way of stopping. There are plenty of other possible failure modes, plus as adults, we're typically heavier and riding in more traffic, than what we remember as kids.

I too spent a year with a not profit that reconed bike for kids. I dont believe I ever saw one that wouldnt work.

I agree with rydabent in that CBs are pretty hard to kill. Seriously wound, yes. But to make totally unuseabe takes a lot of time. I have seen it done, just not at all often. The "usual" kill shot I have seen involves chunks breaking off the two large shell ball tracks. Andy

"How often does a coaster brake break?"

Generally, only once.

In Little Five Hundred racing a lot of single speed brakes go south but rarely do they break. Mostly the brake surfaces are worn down to less than optimum service but will still work under hard back pedaling. In a few cases I have seen the shoes break into two pieces and the spring get de-tensioned but otherwise, If correctly assembled will they fail. Smiles, MH

I've seen it rarely, when something is allowed to go out of adjustment, presumably because someone failed to attach the hub properly, Or perhaps they allowed a cone to get loose while the wheel was off the bike. But one good stomp on the back pedal when things are already falling apart, and . . .

often = failures/usage, not total failures.

I had one where the freewheel would release without warning when standing on the pedals going uphill, but luckily it was a classic folder so I survived the incident without having to shed a tear.

has anyone been down Repack with a coaster brake?

does the hub really smoke?

i would like to try that maybe once or twice,

Not Repack but we regularly do a run down a local mountain where noobies are known to make them smoke, turn blue and even seize almost solid there's so much galling on the shoes. Couple of things that help, helicopter turbine grease that's rated for a very high temperature and beer. Beer is more effective, after a few beers they lose their fear and stop riding the brakes like a sook, that's what kills the brakes. So generally after the first pub it's all good. Last ride I got a cup of frying oil from the restaurant at the first pub and used that to get two hubs going that wouldn't spin. I've though of making heat sinks using beer can fins and a hose clamp around the hub.
It's 10.6 miles and 4200ft of descending, so a fair good workout for the brakes. https://www.facebook.com/groups/1683288705275035

there was an old man up in the mountains above chico ca who used to ride a coaster brake down a long grade,

he had water bottle cages but he didn't drink, used them to squirt the back hub every once in a while. dude was like 100 years old and still riding.

i guess you could pour beer on there but nobody likes to smell warm beer,

Does anyone just piss on it?

While riding?

Standing up and aiming backwards. probably not pedaling

If you ever watch the movie Klunkers Joe Breezer and Gary Fisher had to rebuild their coaster brakes after every downhill run

https://www.amazon.com/Klunkerz-Film.../dp/B00FIKINO2

Excellent movie BTW