If you look at the actual data, the failure rate for Shimano cranks is very small (less than 1% IIRC). ALL products have a failure rate and less than 1% is pretty damn good.
That said, the problem for Shimano was that the sheer volume of failed cranks reached a point where it became an issue for them. But inherent in that is the fact that they sold MILLIONS of cranks during the affected period. They still had a low failure rate, but a low % of a huge number is still a significant raw number.
Right. Small consolation if you were hurt when your crank failed. “Sorry man… you’re a rounding error.” I spent my career in risk management and fully appreciate that a small percentage of a large number is also a large number, but I doubt that most manufacturers would consider “less than 1%” is “pretty damn good”, unless it is a LOT less than 1%.
I used “less than 1%” as I wasn’t sure of the exact percentage…but go ahead and look it up. It is in the initial reports when they issued the recall. It is pretty damn small.
If you have spent you career in risk management, the you know that no product is without failures. It is a statistical fact of life. So your arguement of “unless you were one of those who got hurt” is a logical fallacy known as Appeal to Emotion.
If zero people getting hurt is your threshold for whether a product is brought to market or not, then there are almost no products brought to market.
Hm… looking back through the thread to see where I said anything about “zero defects” and not finding it ANYWHERE. I find it pointless to engage with someone who makes stuff up and puts words in others mouths. But thank you for playing!
Well now you’re just dodging the conversation….you said a defect rate of less than 1% is not acceptable, but now you are saying you never said zero defects. So what is your acceptable defect rate?
The problem here is your hyperbole has exposed the flaw in your argument, but rather than see that, you are just checking out.
I’m not trolling…I’m making a valid, statistically based argument. The fact that you can’t answer the questions posed to you does not make it trolling.
No need for this rudeness.
Sorry Mike, but I would say the HT crank issue is very similar. While there is little to no maintenance that can impact likelihood of crank failure, I suspect cleaning frequency and storage humidity will, plus where the bike is ridden and in what conditions most definitely have an impact.
Equally, leaking pistons result in contaminated pads resulting in terrible braking performance. I’d say that’s a fairly major safety issue that’s perhaps worse than crank failure.
The difference? It’s easier for Shimano to pass off the calliper issue as wear and tear because of being able to say it could be servicing issue and/or seal lifespan, and it’s hard to prove otherwise.
Nailed it there Julian, with my emphasis at the end.
As I and others have said, there is no fundamental flaw in Shimano’s design. I see leaking / cracked pistons from other manufacturers. I see Shimano users (myself included) with no issues. There’s always going to be anecdata out there on random failures due to a manufacturing quality failure or maintenance / riding events - mine, yours, theirs - but that doesn’t mean Shimano calipers are any more likely to fail than anyone else. There’s just not the data to back that up.
I totally get brakes are a critical safety component. The number one reason most brakes perform poorly is users covering the rotors in stuff - spray lubes, detergents, whatever - or rotors picking up contamination spray from the road - oil and leechate from tarmac when it’s wet.
The thing is, brakes don’t fail instantly the way cranks do under peak load resulting in a crash. Brakes get worse over time, and anyone should be able to spot that and get their bike in for a service.
I’m sorry that your calipers are leaking, but your expectation of free replacements after the warranty period seems a bit misguided to me.
Even if you can prove that the leak is due to a design fault, you have used the calipers for over two years. Their remaining value is… not very high. It would be generous from Shimano to offer you a discount on a new caliper, but I certainly would not expect it.
As for the price, they are cheaper than a chainring or many cassettes. People with oil bikes spend much more on keeping their drivetrain alive. I’d be happy to pay a little every two years to restore braking performance.
Edit: everyone wants free stuff, and I would not be mad about receiving a free upgrade. But who is going to spend the money necessary to keep the bike industry alive?
Brakes often/generally get worse over time, but I’ve had Shimano brakes go from good to very bad between rides due to the piston seal leaks, and I’ve only realised that once I’ve set off, only to have a shock when I first pull the brakes.
I’d say hitting something due to the brakes not working is as dramatic as crashing due to crank failure.
Also, most crank failures will have warning signs (creaks, movement in directions there shouldn’t be, etc.), and it’s more a question of whether the rider picks them up and diagnoses the cause.
At the risk of derailing the holey war taking place, it is worth noting that rebuild kits including pistons and seals are available from third parties for Shimano calipers. Amazon and ebay are two sources, and I even saw one selling ti pistons.
Shimano disc brakes at least pre-12 are garbage. I even changed the calipers. Everytime in the podcast they say how good they are it triggers me. How can anything that has a leaking problem (and is noisy with poor performance as a result) be considered good is beyond me.
I was lucky enough to bin all my Shimano gear. I felt bad for the bin.
The constant rotor rub - when I rode out of the saddle or after engaging the brake briefly on descents or when I looked at it wrong - was the main reason I upgraded to the 12-speed Dura-Ace groupset back in January 2022. That 10% or so of increased spacing between the pads and the rotor in the 12-speed system was enough to put an end to the rotor rub.
1 pair of R9170s for me, that had a very slight crack in one piston both front/rear, evidenced by the Fluid Ring of Death, on the backing plate of brake pads. Not sure what happened to them, came with a bike that got sent in.
Other than that, zero problems so far… 
Appreciate the arguments here. I checked one of my calipers and it was indeed cracked. This solves my long standing occasional leaking issue.
Hopefully the new caliper won’t go the same way.
In the event you find yourself in need of spreading those pistons apart, you could consider something like SRAM’s Ultimate Piston Press, or one of the numerous alternatives on AliExpress, etc.
These have the benefit of applying pressure uniformly over the entire circumference of the piston, instead of specific sections, thereby reducing hotspots that could result in the pistons cracking (when using screwdrivers, and similar).
It’s also worth noting that you’re using untested and unapproved random parts on a critical - THE critical - safety feature of your bike.
This sort of conversation is dangerous. Would you fly on an aircraft that had been repaired with random unapproved parts? Would you let your spouse drive your kids around in a car with brake parts from Aliexpress?
When you sell or lend someone your bike, will you disclose that you fitted unapproved parts to the brakes? Would you buy a bike where the owner told you they had done so?
On the recent Geek Warning podcast @Dave_Rome talked at length about safety. And here we are, discussing fitting untested 3rd party random brake parts…all to avoid a repair bill on a critical safety component that would cost less than a dinner out 
This bit, in my opinion, deserves its own discussion topic.
If a product is out of warranty according to the purchase date, when is it acceptable for a brand to deny a warranty claim and use the warranty expiration date as the reason for denying the claim?
1 day, 1 week, 2 months, 3 months, 6 months?
Where can a brand draw a line and expect to not be criticised for denying the claim?
The bit I am disgusted in is that shimano think its acceptable to throw away a whole caliper because of a small part failure.