Strange Crank Failure

ColinJ

Puzzle game developer
Yikes - that could have had extremely nasty consequences! :eek:

I don't agree with this comment though...

BikeRadar article said:
This crank had done some serious mileage, but nothing we wouldn’t expect a crank to be able to withstand
15,000 km or 9,321 miles - even with my relatively limited annual totals I would do that distance in under 2.5 years!
 
OP
dave r

dave r

Dunking Diddy Dave Pedalling Pensioner
Yikes - that could have had extremely nasty consequences! :eek:

I don't agree with this comment though...


15,000 km or 9,321 miles - even with my relatively limited annual totals I would do that distance in under 2.5 years!
I thought that, I could put that amount on a crank in under five years and I don't do serious milage.
 
Location
Loch side.
I read that article this morning and thought it was rubbish. It is a whole lot of speculation and suggestion and innuendo but never gets to the point of why the crank failed. It seems as if the writer didn't examine the crank closely and looked for stress risers or any other cause. There's a bit of mention of adhesive, but since there is adhesive in there, that shouldn't surprise anyone.

I'll admit that it is the first photo I've seen to show how the crank is created. Very interesting that.

Shimano stuff is good. Very, very good and one crank failure is neither here nor there. I've seen probably a dozen failures on different brands, especially old Campag stuff.

Unfortunately it is a really poor article, a lot like the speculation and what-iffery we're seeing on the current you-know-what issue that's bothering us.
 

Ajax Bay

Veteran
Location
East Devon
Trapped moisture in voids during manufacture leading to thermal cycling and failure of adhesive/meniscus. Suggestion that the ?vast majority of failures have been experienced between latitudes 30 north and south (Tropics of Cancer and Capricorn plus a bit).
 

Drago

Flouncing Nobber
Location
Poshshire
Trapped moisture in voids during manufacture leading to thermal cycling and failure of adhesive/meniscus. Suggestion that the ?vast majority of failures have been experienced between latitudes 30 north and south (Tropics of Cancer and Capricorn plus a bit).
Well, the Bike Radar offices are in Quito :okay:
 

wafter

Über Member
Location
Oxford
From a quick google-bash it seems that this issue is only being flagged on Ultegra and Dura-Ace cranks; this poor bloke has had one of each fail; the second being a replacement for the first. He probably had some time to calm down before writing his blog entry, but had that been me I'd have lost my sh*t on the second one and being in the litigous US would be slinging around suggestions of legal action as there's clearly an issue with these products that presents a clear and potentially very serious safety risk to their riders.

Trapped moisture in voids during manufacture leading to thermal cycling and failure of adhesive/meniscus. Suggestion that the ?vast majority of failures have been experienced between latitudes 30 north and south (Tropics of Cancer and Capricorn plus a bit).
Interesting observation. Certainly looks like it's a problem with the bonding; being a luddite I was a bit disappointed to see that this much-touted "Hollowtech" format relies on bits being glued together.

Having just bought a bike with a 105 R7000 groupset I'm relieved that I can't find any examples of such failures on these cranks, although they are a bit newer so have had less time for the problem to occur.. and while being heavier I imagine the assembly process and bonding agents used are probably the same as those in the two higher-end groupsets.

Not what I expect from Shimano tbh; one of the few manufacturers in this industry that I have (had) pretty much 100% faith in / respect for :sad:

It seems that knowledge of these issues is gaining momentum and it'll be interesting to see how the manufacturers handle it.
 

Ajax Bay

Veteran
Location
East Devon
Don't confuse 'Hollowtech' crank design/manufacture with Hollowtech 2 axle and BB 'technology'/Shimano standard. On the same crankset but two discreet design aspects.
 
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