Shimano 9000 Crankarm Failure.

[avalonracing]

Damn, that IG page freaks me out. Especially since my riding buddy broke his DA 9000 cranks in a similar fashion. Yes, I'm 50 pounds lighter than he is but breaking a crank arm shouldn't be a worry when you are sprinting.

[Davist]

the old CNC cranks broke a lot too (cook brothers et al) but they came in purple.. the cold forged ones by the majors were obviously stronger but had stress risers form in the spider portion.

I haven't personally seen shimano break in the wild, but have seen the specialized carbon ones (twice) and had a buddy break the cannondale ones..

From BMX days the welded chrome moly cranks (redline, profile, gt, boss) would break once in a while too..

but agreed, I'd add a 1/4 lb there for a better solution!

[slambers3]

I’m a campagnolo guy through and through, but I’d like to see how many failures shimano has experienced vs total number of those cranks in the wild before freaking out about risk. Shimano has sold hundreds of thousands of those cranksets, a lot of them have seen very high mileage under very abusive circumstances without failure.

[dddd]

Originally Posted by slambers3

I’m a campagnolo guy through and through, but I’d like to see how many failures shimano has experienced vs total number of those cranks in the wild before freaking out about risk. Shimano has sold hundreds of thousands of those cranksets, a lot of them have seen very high mileage under very abusive circumstances without failure.

True, the numbers of Shimano hollow/bonded cranks on the road is huge.
Their designs are tested to high standards and I would say they are known for above average quality control.

And, does anyone know how many crank failures, regardless of brand, are initiated by a crash onto the pedal?
I mean, I've seen a Trek carbon frame end up with a broken DT and ST after a solo-rider crash that I witnessed first hand. Unbelieveably that rider actually rode the flopping bike to another location a few hilly miles up the road where his wife was to pick him up!

[mcteague]

https://www.bikeradar.com/features/s...crank-failure/

https://youtu.be/Rj__lexd_BI

Tim

[dvs cycles]

Has Shimano ever warrantied any of these cases?
Mine is over seven years old but I've gotten more years and miles out of their
older models.

[thirdgenbird]

Originally Posted by dvs cycles

Has Shimano ever warrantied any of these cases?
Mine is over seven years old but I've gotten more years and miles out of their
older models.

It sounds like shimano has even replaced them outside of warranty.

Read the comments on the BikeRadar article above. It’s amazing how many of them are people that have experienced this failure. Some of them multiple times. It seems to be more prevalent in hot/humid climates.

[bfd]

People have been breaking cranks for many many years. Check out pardo for several types of old school cranks and other broken bike parts:

http://pardo.net/bike/pic/fail-001/000.html

Good Luck!

[steveoz]

Interesting article showing the failure of the crank - I wonder how much "hands on" fitting and assembling goes into those cranks. I use epoxy resins everyday at work (for bonding and another for surface finish). Parts HAVE to be degreased and roughed for bonding and wiped down with alchohol before using the finish coat- even human oils can interfere with proper results . It could be that particular SHimano crank was prepped on Friday and glued on Monday - leaving juuust enough time to allow a layer of surface oxidation or contamination to develop.

[Mark McM]

Originally Posted by avalonracing

Damn, that IG page freaks me out. Especially since my riding buddy broke his DA 9000 cranks in a similar fashion. Yes, I'm 50 pounds lighter than he is but breaking a crank arm shouldn't be a worry when you are sprinting.

If you read the BikeRadar article, you'll see that the crank failure wasn't fully
"spontaneous and out of the blue". There had been signs of the impending failure well before it happened, that the rider had ignored. This is true of many bicycle failures - period inspection of frames and components can detect many impending failure before they happen. If you're worried about a particular component, then you shorten the time between inspections.

[Asudef]

Interesting, I wonder if this is the source of my friend's crank issues with chainring wobble so bad you can't dial the chain rub out.

[Velocipede]

Originally Posted by steveoz

Interesting article showing the failure of the crank - I wonder how much "hands on" fitting and assembling goes into those cranks. I use epoxy resins everyday at work (for bonding and another for surface finish). Parts HAVE to be degreased and roughed for bonding and wiped down with alchohol before using the finish coat- even human oils can interfere with proper results . It could be that particular SHimano crank was prepped on Friday and glued on Monday - leaving juuust enough time to allow a layer of surface oxidation or contamination to develop.

These crank arms are put together by hand. The issue isn't the epoxy or cleanliness. They need to redesign the interface and add a locking lip and they would help stop it. But given they barely acknowledge the problem, they will never do this.

[oldpotatoe]

Originally Posted by Velocipede

These crank arms are put together by hand. The issue isn't the epoxy or cleanliness. They need to redesign the interface and add a locking lip and they would help stop it. But given they barely acknowledge the problem, they will never do this.

Pretty interesting. along with DA top pulleys unscrewing and falling out and cartridge bearing headsets that made a whole generation of forks obsolete.

I had an interesting conversation with Wayne Stetina(he still at shimano?) about the above and he says, it's a somewhat cultural thing(not in a derogatory sense) and a mindset of being the BIGGEST dog in the market.
"Cuz they are SHIMANO"...

[GregL]

Do the Shimano MTB cranks exhibit the same failure modes? Or do they use different construction techniques that make for a more reliable bond? I’m curious since this discussion has focused only on the road cranks.

Greg

[Velocipede]

Originally Posted by oldpotatoe

Pretty interesting. along with DA top pulleys unscrewing and falling out and cartridge bearing headsets that made a whole generation of forks obsolete.

I had an interesting conversation with Wayne Stetina(he still at shimano?) about the above and he says, it's a somewhat cultural thing(not in a derogatory sense) and a mindset of being the BIGGEST dog in the market.
"Cuz they are SHIMANO"...

I never had or seen the DA pulley issue but heard about it. The headset thing, they did make a nice headset though.

Yeah, Wayne is still there. Oh, it's totally a cultural thing. It's like when I was at American Classic and I'd find a problem, something Taiwan did wrong. You couldn't come right out and say hey, you goofed or screwed up. You still had to give them deference even though they were wrong. In Shimano's case, they are so massive with hands in so much, they REALLY hate to be told they're wrong.

The crank arm thing is real. It's hard to NOT Acknowledge but they blame it on salt air or whatever. And if you don't live near the ocean, then they blame it on salted roads. The excuses are wild when dealing with them. And they could fix it easily. But it would require new dies and would cost a fortune.

Originally Posted by GregL

Do the Shimano MTB cranks exhibit the same failure modes? Or do they use different construction techniques that make for a more reliable bond? I’m curious since this discussion has focused only on the road cranks.

Greg

I'm sure they have happened. But most mountain bikers would blame it on themselves and their riding and abusive of the bike. And they'd think it's cool. And show it off to their buddies. They are made the same way so it's had to happened.