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Ultegra 6800 drive arm. TORN!?!

Hello.

I'm surprisingly proud of this cycling achievement. Was out the weekend and took a short, sharp, steep hill with a fast climb. To my astonishment, I've managed to tear my Ultegra 6800 (53) crank arm away from the chainset. There's a great big tear in the aluminium casing from the base of the arm across the first fixing. Which has warped the arm and rendered the set useless.
So...
Can anyone shed light on how common an occurrence this is ? In my 30 years of road cycling. I've never managed to get anywhere close to this achievement.
Normally, I'd be miffed at the extra cost to replace the set but given the held opinion that these cranksets are meant to be infallible. I wear it as a badge of honour.

Any thoughts welcome.

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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25 comments

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levestane | 8 months ago
1 like
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wycombewheeler | 8 months ago
0 likes

Obviously this is a known problem. Does anyone know what the failure rate is? I'm not the gentlist on my cranks, being overweight, and often turnng a bigger gear than I should.

Have I been unusually lucky, or would I be unlucky if this happened to me?

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Daveyraveygravey replied to wycombewheeler | 8 months ago
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I'm not sure it is weight or power related.  Both mine lasted around 4 years, I'll have a look at Strava and Veloviewer to see if I can get an approx mileage.

The parts are bonded together, I think the glue gets eaten away by crap weather.  My bike gets ridden year round, no mudguards and I'm not the best at maintenance and post-ride cleaning.

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marmotte27 | 8 months ago
1 like

Spécialités TA still do the classic Pro 5 vis:

https://specialites-ta.com/130-pro-5-vis

Well, from time to time anyway. But might be worth waiting for. And looks better on a slender steel frame.

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marmotte27 replied to marmotte27 | 8 months ago
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Weight Dura Ace Crankset (according to the first google search result) 615g (50/34)
Weight TA Pro 5 vis (according to velobase) 611g in 52/42. (Mine's a 44/26, but not going to take it off to weigh).

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marmotte27 replied to marmotte27 | 8 months ago
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Watching the Hambini video posted above, I've thought more about modern road bikes in the last 15 minutes than in the last 15 years...
I'd always wondered how Shimano and now even Campa ended up designing such eyesores.
But now I see it's (albeit perversely) logical: huge ugly carbon frame -> huge ugly crank...
So function follows form instead of the other way round.
And thus you are in trouble...

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wtjs | 8 months ago
3 likes

Ultegra Pasta Cranks- a true saga of our times

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Fignon's ghost replied to wtjs | 8 months ago
0 likes

I never knew this and won't buy another one. It's never been hammered.

Is the r8000 as bad? If so, FSA light as recd by shiny.

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Jimnm replied to Fignon's ghost | 8 months ago
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Fignon's ghost wrote:

I never knew this and won't buy another one. It's never been hammered. Is the r8000 as bad? If so, FSA light as recd by shiny.

Go for Shimano 105 cheaper and does the job. I did and bought with shorter cranks 172.5 are too long. I bought 170mm but should have considered 165mm. Maybe next time. 

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Fignon's ghost replied to hawkinspeter | 8 months ago
1 like

Thanks. Oh well. Will have to chalk it up as a product failure and not Hulkamania.

I've never used anything other than Ultegra or 105. Any alternative suggestions ?

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Spangly Shiny replied to Fignon's ghost | 8 months ago
1 like

FSA SLK Light, solid carbon; light, strong and not too expensive (despite Keith Bontrager's assertions).

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hawkinspeter replied to Fignon's ghost | 8 months ago
2 likes
Fignon's ghost wrote:

Thanks. Oh well. Will have to chalk it up as a product failure and not Hulkamania.

I've never used anything other than Ultegra or 105. Any alternative suggestions ?

105 should be fine - it's only Ultegra and Dura-Ace that have the problem as they're hollow bonded.

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Fignon's ghost replied to hawkinspeter | 8 months ago
1 like

Thanks. I'm pretty sure 105 will do for me. However, I'm on a mission to test out your 105 conclusion.

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hawkinspeter replied to Fignon's ghost | 8 months ago
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Fignon's ghost wrote:

Thanks. I'm pretty sure 105 will do for me. However, I'm on a mission to test out your 105 conclusion.

Go for it - I haven't seen any reports of 105 cranks breaking

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Welsh boy | 8 months ago
1 like

"a short, sharp, steep hill".  Not Caerfilthy mountain getting ready for the ToB by any chance?  What length cranks do you ride?  A pair of 165mm Ultegra and/or 170mm Tiagra chainsets in Newport going for a very resonable price if you are interested.

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Fignon's ghost replied to Welsh boy | 8 months ago
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No. Not Philly. Although I did manage to piss off a host of motorists queuing up on the single lane. I literally got stranded on the climb out and it was obviously a technical. My gesticulating fell on unsympathetic eyes n ears. The muppets had to beep, scowl and moan.

I could've happily dechained and "gone to town"!

No. Typical cyclist. Too polite. I just pulled the bike into the hedge and let them pass.

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ChrisB200SX | 8 months ago
3 likes

This looks a little different to the usual Ultegra failure, which tends to be the debonding of the arm section. Maybe debonding at one edge has caused a weak point there which has resulted in a crack that has now spread?

Does appear like you've mangled it with huge torque though, chapeau!

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Fignon's ghost replied to ChrisB200SX | 8 months ago
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Thanks Chris.

Yes. The tear begins at the earliest torque point.
It's not as if I use this one all the time. I have two regular road bikes. Doing anything from 50 to 300 miles a week between them.

I'll probably go for the r7000 instead. I'm a hobby rider but, even though I say it myself, have legs like Abdoujaparov!

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Fignon's ghost | 8 months ago
3 likes

Here we go...

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Daveyraveygravey replied to Fignon's ghost | 8 months ago
2 likes
Fignon's ghost wrote:

Here we go...

  Looks very typical to me!  I've got through two in 8 years, usually around 4 years of use.  There's a website on Instagram called "thankshimano" which has loads.

I managed to get a warranty replacement the first time, but it took a lot of nasty threatening letters & emails.  I've now switched to 105 cranks in the hope they last longer.

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Fignon's ghost replied to Daveyraveygravey | 8 months ago
1 like

Davey. Thanks for deflating my balloon! FWIW. I did it on 172.5.

My other is a 105. As Chris pointed out. There are two sections to the ultegra 6800 composition. Compared with the 105, which looks a solid, single cast unit. Presumably it's slightly heavier. 105 is good enough for me.

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ChrisB200SX replied to Fignon's ghost | 8 months ago
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Fignon's ghost wrote:

Davey. Thanks for deflating my balloon! FWIW. I did it on 172.5. My other is a 105. As Chris pointed out. There are two sections to the ultegra 6800 composition. Compared with the 105, which looks a solid, single cast unit. Presumably it's slightly heavier. 105 is good enough for me.

I'm not sure 5800 is actually any different in the 6800's general construction, maybe they used a different/thinner alloy or different adhesive for Ultegra? I've got two 5800 and one R8000. I'm hoping the latter is less prone to the earlier Ultegra crank death.

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Daveyraveygravey replied to Fignon's ghost | 8 months ago
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Fignon's ghost wrote:

Davey. Thanks for deflating my balloon! FWIW. I did it on 172.5. My other is a 105. As Chris pointed out. There are two sections to the ultegra 6800 composition. Compared with the 105, which looks a solid, single cast unit. Presumably it's slightly heavier. 105 is good enough for me.

Both mine were 6800.  I got the 105 off Ebay, lightly used for under 50 quid, so even if it DOES go the same way, I don't feel like it has cost me a huge amount. 

I was furious the first time as I hadn't heard about it before.  I was on my way to Rosedale Chimney in N Yorks, and if it had failed going up there it could have been nasty kiss  I would think long and hard about a bike with Ultegra ever again, which is a shame, because it has been great apart from that.

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McVittees replied to Daveyraveygravey | 8 months ago
1 like

For what it's worth, virtually all the weight difference between Ultegra and Shimano cranks is in the chainrings. The arms themselves have only a very minor weight difference, something like 20g when I weighed mine.

Here you go, look: Ultegra vs 105 

 

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