FAILURE Shimano Cranksets

Discuss light weight issues concerning road bikes & parts.
schlafen
Posts: 74
Joined: Sun Mar 24, 2019 11:51 pm

by schlafen

2lo8 wrote:Drillium is taking an overbuilt part, lightening it, not riding it much or at least not on the training bike, and not being surprised it breaks if it does. If done right, it's material removed in low stress areas, rather than removing material in high stress areas already prone to failure. This is taking a part that has failed, and attempting a fix that is worse than the factory method which already failed, and expecting the inferior fix to work better.

There is no way in which these two things are comparable, even if Shimano screwed up big time. It being a bicycle has nothing to do with whether or not failures happen, as evidenced by the fact that these cranks are on bicycles, and also fail, meaning it being a bicycle didn't prevent them from failing the first time.

Neither is a logical argument for JB welding cranks back together.
The only logical question in this instance would be - does shimano use an inferior bonding agent than jb weld?
The only certainty I have is that I don't know.
What I do know first hand is that shimano's glue must be sh1t if it fails.
Have you seen any hollowtech crank arms repaired with jb weld fail?
I haven't.

So assuming that jb weld is an inferior bonding agent, to an unknown bonding agent which failed first, is stupid logic, sorry.

As far as drillium goes, I'm not that old, can't say I believe you, heh.

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by Weenie


2lo8
Posts: 549
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

You're comparing a sample size of n=1 (or 0) vs a sample size of n=some huge number. The actual rate of failure of Shimano cranks is very low except for some riders that seem to check all the boxes for crank failure. You're not even accounting for all possible factors, like surface prep. It's possible to use any perfect adhesive and end up with an inferior bond due to bad surface prep, JB Weld, or Shimano mystery glue. Or other factors like mixing JB Weld A and B ratios perfectly.

Furthermore, my understanding is most of these failed cranks have had lots of mileage, JB weld crank was briefly tested for immediate catastrophic failure. It appears it is not the case that these cranks fail within the first few rides because shear/tensile whatever strength of the bonding agent is exceeded due to peak loads, so it is questionable if that n=1 is even comparable. It is not that the epoxy is initially weak, it is that it somehow weakens over time, due to aging, hard use, chemical exposure, high mileage, fatigue somewhere, or something else.

Clearly you want to believe what you want to believe, I can't, won't, don't care to stop you from risking life and limb to spend a few hours to save a couple hundred bucks. You do you. But for anyone else that might be reading this thinking about JB welding a crank, those are not sound arguments.
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uraqt
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by uraqt

@2lo8,

You are trying to justify a company's bad behaviour. And that company has a history of bad behaviour.

C

2lo8
Posts: 549
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

uraqt wrote:
Tue Apr 21, 2020 6:02 am
@2lo8,

You are trying to justify a company's bad behaviour. And that company has a history of bad behaviour.

C
I am not at all. Please actually bother to read my posts. I am saying JB Weld doesn't solve Shimano's bad behavior. Shimano's culpability goes beyond the economic damages of some tubes of JB Weld. As I have pointed out more than once, there is risk of injury and to life and limb, which JB Weld doesn't fix.

The only "kind" thing, if you can call it that, I have inferred about Shimano's epoxy jobs is it's probably better than some random person attempting to assemble it with JB Weld at home. But please tell me this is saying I am justifying a company's bad product.
[14lb(6.35kg) of no carbon fiber]
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uraqt
Posts: 984
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by uraqt

The actual rate of failure of Shimano cranks is very low except for some riders that seem to check all the boxes for crank failure.
I will admit I didn't read the full thread as my point of veiw is clear earlier in the thread...however the above is what I did read...

C

2lo8
Posts: 549
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

uraqt wrote:
Tue Apr 21, 2020 7:29 am
The actual rate of failure of Shimano cranks is very low except for some riders that seem to check all the boxes for crank failure.
I will admit I didn't read the full thread as my point of veiw is clear earlier in the thread...however the above is what I did read...

C
It's 100% factual. I'm sorry you have an issue with facts.
[14lb(6.35kg) of no carbon fiber]
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schlafen
Posts: 74
Joined: Sun Mar 24, 2019 11:51 pm

by schlafen

2lo8 wrote:You're comparing a sample size of n=1 (or 0) vs a sample size of n=some huge number. The actual rate of failure of Shimano cranks is very low except for some riders that seem to check all the boxes for crank failure. You're not even accounting for all possible factors, like surface prep. It's possible to use any perfect adhesive and end up with an inferior bond due to bad surface prep, JB Weld, or Shimano mystery glue. Or other factors like mixing JB Weld A and B ratios perfectly.

Furthermore, my understanding is most of these failed cranks have had lots of mileage, JB weld crank was briefly tested for immediate catastrophic failure. It appears it is not the case that these cranks fail within the first few rides because shear/tensile whatever strength of the bonding agent is exceeded due to peak loads, so it is questionable if that n=1 is even comparable. It is not that the epoxy is initially weak, it is that it somehow weakens over time, due to aging, hard use, chemical exposure, high mileage, fatigue somewhere, or something else.

Clearly you want to believe what you want to believe, I can't, won't, don't care to stop you from risking life and limb to spend a few hours to save a couple hundred bucks. You do you. But for anyone else that might be reading this thinking about JB welding a crank, those are not sound arguments.
The reason for n=1 is that this is the only one known to me to split at the seam.
If you look carefully at the pictures of broken cranks posted here or anywehere, they are broken, not split.

Maybe shimano has a poor process, in the shed they do the bonding and people are assembling them with greasy fingers after eating burgers. Who knows. No one as shimano ain't tellin, that's for sure.
Big companies mess up all the time and cut corners to save money. There's a lot of money to be saved from glue at the level they're using it. 1000 cranksets destroyed in total maybe? A drop in the bucket.

(Imagine the poor process caused by workers pinch glue to sniff it, that would be hilarious, now that they found the guy pinching the glue, everything's back to high, no pun intended, shimano quality)

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2lo8
Posts: 549
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

Just because there's a reason n=1 doesn't mean n!=1. This is again, not a real argument. It split at the seam because the owner caught it early and deliberately split it at the first sign of failure. It did not split on its own. The bonding process is done by robots, Shimano has in fact told this much, along with a few other details of the process, and there's still no good reason to think that some random guy using JB Weld in his garage is going to do a better job. I have no idea why you think JB Weld crudely mixed in someone's garage and cured overnight is some sort of superior or even a particularly good bonding system when compared to application specific industrial adhesives, except that for some reason you think that Shimano is less competent than a duct-tape engineer because of a higher than typical but still fairly low rate of (dangerous and unacceptable) failure. It's a decent off-the-shelf consumer grade epoxy, that is more than adequate for many applications, that's about it. Shimano's failure rate is bad, but it's not duct-tape engineering bad. Again, you are free to believe what you want to believe, but this is just wishful thinking.
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shotgun
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Location: Philippines

by shotgun

Maybe it's not just the bonding agent, but a multitude for factors. Mileage, heat, sweat and humidity. Could be the bonding agent's reaction to those? Or the reaction with those to the aluminum?

What's clear is that they should have done a more thorough testing before pushing a process and design into produciton, (not just quality control at the end). I'm not saying that they didn't try, but fact remains it's an issue. I've had 2 falures out of 2 cranks. That's a 100% hit rate for me.
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kgt
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Location: Athens, Greece

by kgt

+100
A hi-end and expensive product like a DA crankset is should not fail, even after many years of hard use. This is the only fact.

jamesstirling
Posts: 4
Joined: Mon Jan 16, 2017 7:53 pm

by jamesstirling

Mine failed 2 days ago. Bike is 5 years old but only covered circa 6,000 miles.
I'm trying for warranty even though I know its only 2 years, but I do not think they have been used excessively.

Also got a nice shiner on my leg for my troubles.
Big shout out to JeJames....they lent me some 105 cranks to get me by! :thumbup:
WhatsApp Image 2020-06-03 at 08.27.59.jpeg
WhatsApp Image 2020-06-03 at 08.41.13.jpeg

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kgt
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by kgt

Ouch!

madik
Posts: 226
Joined: Sun Jan 08, 2017 12:44 pm

by madik

jamesstirling wrote:
Fri Jun 05, 2020 9:41 am
Mine failed 2 days ago. Bike is 5 years old but only covered circa 6,000 miles.
I'm trying for warranty even though I know its only 2 years, but I do not think they have been used excessively.

Also got a nice shiner on my leg for my troubles.
Big shout out to JeJames....they lent me some 105 cranks to get me by! :thumbup:

WhatsApp Image 2020-06-03 at 08.27.59.jpeg

WhatsApp Image 2020-06-03 at 08.41.13.jpeg
Can you tell us where are you located and how is your bike stored? I heard that the cranks failing due to accelerated oxidation in warmer climates. So basically the closer to equator the faster is the process.
Functionality > Performance > Weight

jamesstirling
Posts: 4
Joined: Mon Jan 16, 2017 7:53 pm

by jamesstirling

madik wrote:
Fri Jun 05, 2020 12:58 pm
jamesstirling wrote:
Fri Jun 05, 2020 9:41 am
Mine failed 2 days ago. Bike is 5 years old but only covered circa 6,000 miles.
I'm trying for warranty even though I know its only 2 years, but I do not think they have been used excessively.

Also got a nice shiner on my leg for my troubles.
Big shout out to JeJames....they lent me some 105 cranks to get me by! :thumbup:

WhatsApp Image 2020-06-03 at 08.27.59.jpeg

WhatsApp Image 2020-06-03 at 08.41.13.jpeg
Can you tell us where are you located and how is your bike stored? I heard that the cranks failing due to accelerated oxidation in warmer climates. So basically the closer to equator the faster is the process.
I'm located in Derbyshire, England. Bike has mostly been stored in my conservatory so, slightly cooler than room temperature. I have read about the oxidation, and many report of the white powder of which mine had also.

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pdlpsher1
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by pdlpsher1

Glad you're OK and didn't get hurt more than a big leg bruise. Shimano should be held accountable and at least honor the warranty on a goodwill basis.

by Weenie


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