BTinNYC 

If my Hollowtech crank arm breaks, my awesome biking power can be The Only Cause.

shelbyfv

Stay safe!

am8117

Likewise!

Bald Paul

Two bikes with Ultegra Hollowtech cranks. Thousands of miles on each. Zero failures.
Show me hard stats on failure rates and MAYBE I'll worry. (But probably not.)

shelbyfv

But, but, but.... are you sure you don't want to order a couple of Sora cranks, just to be safe? Maybe some solid rubber tires as well?

kek

Shimano have more than 2 types of hollow designs

hollow forged v0
glued bonded v1 (light-weight-glued+with-spider+left-pinchbolt)
glued bonded v2 (heavy-weight-glued+with-spider+left-pinchbolt)
glued bonded v3 (light-weight-glued+direct-mount+left-nopinchbolt)

ultegra crank arms:
10s left v0 right v0
11s left v0 right v1
12s left v0 right v2

dura-ace crank arms:
10s left v0 right v0
11s left v1 right v1
12s left v0 right v2

xtr crank arms
10s left v0 right v0
11s left v2 right v0
12s left v3 right v3

all other cranks (grx,105,xt,slx) uses v0 or non-hollow design *

v0 safe, v1 fails, v2 unknown, v3 safe

* grx=hollow forged rx810 (fc-rx600=non-hollow); 105=hollow forged 5600-r7000 (fc-5500=non-hollow); xt=hollow forged m760-m8100 (fc-m750=non-hollow); slx=hollow forged m660-m7100 (dx fc-m650=non-hollow)

am8117

Better Tourney and gallon of sealant please.

Btw that’s the issue at hand Shimano won’t make the stats public, if they did one would know if to be more concerned eg living in humid climates or maybe a particular batch was made like that.

Anyhow let’s see what will trickle down … to Sora 💁🏻‍♂️

Igor_M

Interesting.
Not to question you, but rather, delve deeper into the topic, could you share the source(s) for this info?

am8117

So I am at a loss now here holding in my hand freshly arrived but old design R460 which should be Tiagra level (it came about about the same time as 4700) but has the old design.

I know it's not of primary interest because everything else than dura-ace and ultegra was supposed to be safe, but I wonder what happened here. The left crankarm is old-style non-hollow scooped out, but the right almost looks like the glued kind (as opposed to rounded edges hollow forged). More confusingly when I look at the 4700 that I have here both left and right crankarms are old fashioned scooped out. I clearly remember the 4600 which this design comes from was scooped out, so they retained the 5-arm design for oldish looking crankset but used new technology on only one side meanwhile the more popular (than non-lineup R460) Tiagra that came out same time has the old scooped crankarms on 4-arm design?

So now I am also curious where the info above came from.

nomadmax 

So the GRX 810 crank isn't hollow and bonded?

am8117

Not that I know the answer, but I was thinking this same way, it's rather at the higher end so how come. But GRX came rather late, maybe late enough for Shimano to not to use the hollow glued (at least of the first crack-it-once-shame-on-it iteration)...

That would allow to guess since when Shimano knew of the problem and considered it serious enough to avoid for new designs ... but kept selling off the DA and Ultegra stock.

Fredo76

That the crank in question is under-engineered seems self-evident, even without statistics.

Terms like garbage, POS, utter rubbish, etc., would remain opinions. And they are mine.

am8117

So if one follows Shimano's own web, it would be appear the GRX is not hollow crankarm at all ...

https://bike.shimano.com/en-EU/techn...ollowtech.html

It seems up to date since the latest ones are listed. Of course they do not go into lengths explaining "vX" as per kek's designations above but it would fall in line with his "v0 or non-hollow" for "all others."

This would mean lots of Shimano's cranks are not even hollow.

am8117

Just revisiting this as I now noticed that Shimano's web on "Technology" has three separate links for "Hollow":

1) Hollowtech (crank arm): https://bike.shimano.com/en-EU/techn...ollowtech.html

2) Hollowtech II (shows cranksets but only talks about bottom brackets): https://bike.shimano.com/en-EU/techn...lowtech-2.html

3) Hollowglide (just concerning the big ring): https://bike.shimano.com/en-EU/techn...llowglide.html

As the Hollowtech seems referring ancient racetrack DA and even Octalink FC-T521 it would explain what happened here. The two have nothing in common, one is about void in the crankarms and another in the spindle.

GhostRider62

They don't have failure statistics because they have no consumer reporting system because they don't care. No different than SRAM or Zipp. If you as a customer call with a design problem, they tell you to piss off.

One would hope Shimano evaluated potential failure modes and their effects during the design. It should not have taken a rocket surgeon to foresee this issue as a potential field failure

It looks like the bond separation between the two clamshell halves fails in a "safe" mode

am8117

That is safe to assume, but the publicity eg on youtube gives customers enough to go and see what to buy next. I do not mean something other than Shimano, I mean e.g. 105 instead of Ultegra. It would have helped a lot if they were more open about which was made with what technology (it is somewhat buried in lineup chart PDFs but not to this detail in this specific case). The move from forging to bonding was so silent one would believe the product quality was not in mind, but production costs. Ironically this happened in the highest margin category.

GhostRider62

But what about consumers like me who would not put a 3rd tier part on their bike?

I went with another brand. Carbon. 583 grams with power meter. 105 is a boat anchor

am8117

Just want to correct myself as I saw the like so that nomadmax is not misled. By Shimano specs charts the RX810 actually *do* have hollow crankarms, not the RX600 though.

Adding screenshot and PDF here, it is public on Shimano web but it downloads forever for some reason despite being a small file, GRX cranksets are page 123 (120 if you go by the footer markings).

NB Still impossible to tell what kind of hollow it is ...

shelbyfv

Fighting words for the inverse snobs!

am8117

And that's a great example how to lose a customer and nothing wrong with your preferences. Perhaps they might have kept you if they addressed it, explained the issue, e.g. mentioned in PR statement they are moving on to different bonding method, and rather than full recall if not deemed safety issue eg provide extended warranty. That and e.g. tossing in some sugarcoated white lie (e.g. in only corrodes in humid climates) would have been better ... or not .... for them.

One way or another at least you get to know "on the internet".

am8117

There's nothing wrong having different preferences when one does not impose theirs on all others.

shelbyfv

tcs

FWIW I ordered newly fabricated, factory fresh springs, pawls and an axle key for my pre-WWII Sturmey-Archer AW.

veganbikes

Oh shoot I didn't know that my cranks were gonna asplode! I have had my 6800 cranks for 5 years now and no issues. I also work in a shop and have done 1 Shimano crank warranty in the past 8 years and that was a bent Dura Ace Power Meter arm from a co-worker it was still completely whole and only slightly bent.

I am not saying that one cannot have an issue just not something I have seen widespread beyond this thread.

CliffordK

Yet if you have Ultegra or Dura Ace 9-speed shifters, then the little plastic shifter cover is almost unavailable.

If you have AX brake levers, the brake hoods are almost unavailable. Other woes?