FAILURE Shimano Cranksets

Discuss light weight issues concerning road bikes & parts.
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nickf
Posts: 580
Joined: Sat Mar 06, 2010 10:34 pm

by nickf

wheelsONfire wrote:It seems this is due to corrosion, humidity and salt?
Perhaps in conjunction with a twisting load when we pedal it work itself off or in some cases crack?

So Shimano Hollow Technology is bascially a U-profile with a reversed U-profile glued on?


Its humid here in Orlando for sure but no salt water to worry about this far inland. The customer lives and rides in the central florida area. The glue on the inside was dry and chalky. This is a recreational rider.

by Weenie


PedroS
Posts: 3
Joined: Mon Nov 23, 2015 12:18 am

by PedroS

I wonder just how wide spread this really is. Is it design flaw or just a bad run of cranks? I just purchased a full 6800 group hang on a new Ti frame and now I'm wondering if I should for forego the crankset and find a nice 6700 crankset on eBay.

moonoi
Posts: 436
Joined: Sat Nov 21, 2015 3:04 pm

by moonoi

I dunno but here in Thailand there seems to be an increasing number of failures, this happened to one of our club members a few weeks back, Shimano swapped it out under warranty. Failed after just 2000km/5 months.

I just got a new Ultegra crankset on my M9 and quite worried about whether it is going to fail.

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RDorna
Posts: 1
Joined: Fri Mar 09, 2018 9:41 pm

by RDorna

Ultegra 6800 Crank failure? I have a private collection! 8) The fist one I threw in the trash. Should be 7, not ONLY 6... SHOULD BE A SMILE FACE WITHOUT TEETH TOO
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MyM3Coupe
Posts: 137
Joined: Thu Nov 24, 2016 10:32 pm

by MyM3Coupe

It’s a raging failure. I’m in the US and have seen this on several peoples Ultegra cranks. Shimano needs to do a recall or get badly sued when someone gets hurt.

alcatraz
Posts: 971
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I don't remember my chemistry very well but it could be possible that something has started a corrosion between the two bonded pieces. Maybe a foreign element creating a galvanic cell. I would clean it thoroughly and apply a light layer of oil or thin grease. Polish that baby up after.

I recently got a cheap sisl2 crank which are two bonded alloy pieces and I did notice that corrosion had attacked it and started getting inbeteen the bonded layers. This is not good. I took some oil on a rag and wiped the crank down. It was bone dry and looked rather dusty when I got it. Probably a result of leaving it in a damp and dirty place without any previous treatment for a longer time.

/a

Geoff
Posts: 5136
Joined: Sat Dec 13, 2003 2:25 am
Location: Canada

by Geoff

:shock:

NJCyclist
Posts: 22
Joined: Tue Aug 30, 2011 4:13 pm

by NJCyclist

Is there any information on the prevalence of these failures? I have a 6800 crank on one of my bikes and I'm a big rider, putting a lot of force through the cranks. Would it be prudent to move away from the Ultegra crank?

wingguy
Posts: 3948
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

Having worked in a large, road oriented bike shop through the entire 6700, 6800 and now 8000 eras of ultegra I have never seen an Ultegra crank failure, or even any incipient signs of this kind of failure.

Just think how many of these cranks are out there. It and 105 are far and away the most popular ‘race level’ cranks in the world. Even if there are quite a few documented failures the rate of occurrence is still vanishingly small, IMO.

NJCyclist
Posts: 22
Joined: Tue Aug 30, 2011 4:13 pm

by NJCyclist

I figured the failure rate was quite low. I suspect it's not a design flaw but instead a bad batch made with bonding compound that wasnt' to spec.

2lo8
Posts: 440
Joined: Thu Mar 31, 2016 10:32 am

by 2lo8

wingguy wrote:
Thu Apr 19, 2018 5:02 pm
Just think how many of these cranks are out there. It and 105 are far and away the most popular ‘race level’ cranks in the world. Even if there are quite a few documented failures the rate of occurrence is still vanishingly small, IMO.
Pretty sure 105 use the tube-pinched-shut-at-the-pedal-eye-end construction of older hollowtech cranks at least up through 5800, which could explain it. I don't have 5800 anymore, but I remember checking and noting that it did not appear to have bonded construction. 6700 for that matter too. I think the bonded cranks are 9000 and 6800 onwards. This bonded construction saves all of 20g(?) between 5800 and 6800 arms.
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shotgun
Posts: 195
Joined: Tue Dec 30, 2008 3:38 pm
Location: Philippines

by shotgun

My 6800 crank failed on me 2 weeks ago. Similar issue that the top portion of the crank split. Adhesive failure I guess. Good thing I was less thatn 5km from my car. I thought it was a loose cleat since my right heel would brush against the chaistay.

I've had the crankset for 2 years, 80% of the time it's used indoors. I don't produce loads of watts, but I figure that having it strapped to a trainer increases crank stess.

shotgun
Posts: 195
Joined: Tue Dec 30, 2008 3:38 pm
Location: Philippines

by shotgun

NJCyclist wrote:
Thu Apr 19, 2018 2:29 pm
Is there any information on the prevalence of these failures? I have a 6800 crank on one of my bikes and I'm a big rider, putting a lot of force through the cranks. Would it be prudent to move away from the Ultegra crank?
Myself and another training buddy had our 6800 crank fail on us. We're both under 70kg and shell out low watts (under 300 FTP I reckon).

XCProMD
Posts: 584
Joined: Sat Jan 26, 2008 10:25 am
Location: Cantabria

by XCProMD

ImageImage

I’ve found these with a quick search on my mobile (can’t find my own DA though) but I’ve seen - heard of dozens of cases.




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by Weenie


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wheelbuilder
Posts: 445
Joined: Wed Feb 08, 2017 2:10 am

by wheelbuilder

wingguy wrote:
Thu Apr 19, 2018 5:02 pm
Having worked in a large, road oriented bike shop through the entire 6700, 6800 and now 8000 eras of ultegra I have never seen an Ultegra crank failure, or even any incipient signs of this kind of failure.

Just think how many of these cranks are out there. It and 105 are far and away the most popular ‘race level’ cranks in the world. Even if there are quite a few documented failures the rate of occurrence is still vanishingly small, IMO.
Interesting. I also work in a road oriented shop only a couple days a week, and I have seen four.

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