Shimano Recall
 

PSA

https://www.cpsc.gov/Newsroom/News-R...a-Crash-Hazard

https://www.cyclingnews.com/cycling-...ankset-recall/

https://www.cyclingweekly.com/news/s...rankset-hazard

The cranks should have been recalled based on looks alone.

The recall happened a long time ago, this is the penalty they must pay for damages/negligence

So Shimano had quietly made 9 changes to these cranksets while they were still publicly denying there was anything wrong. I wonder what those changes are. The one visible change I can see, is that the 12 sp cranksets have wider arms. This makes them stronger but does it do anything to solve the underlying issue of glue separation followed by moisture getting inside and causing galvanic corrosion between the steel axle and the aluminum spider?
It’s mind boggling that they continue making glued together cranks instead of going back to the welded hollow cranks like they used to do back in the 10 speed era.

Should have stuck to solid forged cranks IMO

https://i.ebayimg.com/images/g/vrcAA...pfM/s-l140.jpg
as advertised for folding bikes...
Ebay search: 170mm Anodized Folding Bicycle Crank Arm 130BCD Chainrings Crankset with BB

any guesses on how soon they begin to break?

How does this relate to a years-old Shimano recall?

So I had my Ultegra 6800 crankset inspected about a year ago and of course it passed inspection but I have no confidence in it at this point. A Praxis Alba looks like a solid unit so I'll likely go that route.

I prefer the old metal cranks. :innocent:
https://cimg1.ibsrv.net/gimg/bikefor...47ad6658f3.jpg
Simple.

https://cimg5.ibsrv.net/gimg/bikefor...2b4c1d8de7.jpg
Nothing to come un-bonded.

https://cimg2.ibsrv.net/gimg/bikefor...84e656047.webp

not to you, that's for certain. :p

well... if you squint REAL hard, make some odd groaning sounds, wrinkle your oversized brow, and pucker up yer lips around your tongue super tight... you may actually begin to see the point i made..

or a nurse will come into your room, and change your diaper, one of the two
:lol:

hint: future recall awaiting multiple lawsuits.

One difference I've noticed between my 6800 cranks and 8100 ones is that 8100 have a plastic insert right after past the preload threading in the axle, perhaps to seal the inside of the axle-spider connection more?

Criminal defendants don't get to plead innocent and still get a plea deal.

If their engineering department is ethical, they have been screaming upward about this too. I guess TQM is finally dead

Me too either 7700 or/and 7800 cranks, never seen one ever fail.

The Ultegra 6700 crankset on my 2013 Specialized Roubaix Comp looks exactly like the 6800 in the first link.
Should I worry?

The 6700 crankset is a five arm design.

So the issue was that only having four caused the breaking?

No but it doesn’t look the same and apparently isn’t subject to the same flaw. It was only the 6800, 8000 (and 9000/9100 DA)

Check the shimano recall including batch numbers if you are concerned.

It's not a matter of 4 arms vs 5. It's a matter of the glued-together construction of those particular Ultegra and Dura Ace cranksets. The 105 5800, R7000, R7100, etc all have 4 arm constructions and they have no cracking/separation problem. Because they do not use that glued-together construction.
https://i.ebayimg.com/images/g/6AgAA...V/s-l1600.webp
Look at the fine split line along the edge of the right crank arm here. That's where the two halves of the crank arm are glued together. On the Ultegra cranksets the left crank arm is not glued together. So you don't see any split line there. On the Dura Ace cranksets, both left and right crank arms are glued together.

Thanks. I can see the seam.
Why would they want to make and glue 2 piece crank arms? Cost? It seems cheaper to make a one piece than 2 that have to fit perfectly.

Weight savings and possibly manufacturing reasons to achieve the desired result. Hollow crank arm is lighter than a solid crank arm.

Many passenger airplanes today and since before the turn of the century have a lot of glued together parts. When it is done correctly, it works better than many other methods of fastening.

I still prefer forged hollowtech II cranks over glued once but I am an old school person.

For the same reason the bike frame and many other components are made of tubes and not rods. A tube is stiffer for a given amount of material, limited by the point it's not durable enough against dings or buckling like a tin can. They have hollow chain rings as well. Shimano does have hollow welded arms in its catalog sometimes. This failure is a specific mistake in the design, not the basic idea of making it this way. Shimano are not the only ones who make hollow cranks. They don't do carbon cranks, but hollow carbon cranks can be amazingly light weight. There have been other kinds of hollow cranks. There were BMX cranks that were tubes welded at an angle and there were cranks with arms drilled out like a pistol barrel.

Here's a photo I found of an earlier Shimano crank

https://cimg8.ibsrv.net/gimg/bikefor...519debe6ff.png

and here's a SRAM XX1 carbon crank from when they started DUB bottom brackets 8 years ago. As you can see they are also putting full trust in a glue/aluminum joint

https://cimg9.ibsrv.net/gimg/bikefor...0954baa4ad.png