Ultegra chainsets

[Magpie]

Hi , I’ve an ultegra 6800 chainset that has has broken right side arm after 30 months of use. The LBS suggests this is an not uncommon issue, looking on the internet suggests this happens , while I understand it’s out of warranty and need to cop the replacements costs, but is there an alternative so it won’t happen again in a couple of years or has Shimano done anything to improve the product?

[Duck!]

I would not go so far as to say it's "not uncommon", but yes, there are cases of cranks separating. Tne R8000 series which has been available fot almost a year now replaces the 6800 model, and is a bit beefier in the right arm construction.

[Magpie]

As a follow up, there are now numerous posts regarding failures of late model Shimano cranks. The 2 cases I’ve now seen first hand have been from bikes that lived in Dubai and Hong Kong and were subject to cyclical high ambient temperature/humidity, then then kept in an air conditioned apartment, which fits with some peoples theories for the cause of the failures.
I now have DA9100 which is great and live in a less extreme environment.

[stevenaaus]

Hmmm ... Thermal expansion/contraction is a powerful force, especially when differing alloys/metals are joined ?.

[Duck!]

It's not different materials; the inner & outer parts of the crank are made from the same alloy, but glued together rather than the welding of older Hollowtech cranks. Delay between surface preparation and bonding may allow oxidation to occur, affecting the strength of the bond, thus more susceptible to environmental extremes.

[Magpie]

https://www.bikeradar.com/news/shimano- ... tid=Zxz2cZ

North America has apparently issued a recall of certain hollow tech Shimano chain sets due to the delamination of the cranks, would be good for this to be extended to other parts of the world

[Duck!]

See also thread in the General section. The recall is global, however the timeframes for addressing it will vary by region.