ralphs

I used to work for an aerospace firm- building satellite subsystems. We used a variety of specialty epoxy adhesives for bonding components together. We could control adhesive thickness to +/- 0.002 inches to ensure optimum bond strength.
One year we did a comparison test of the adhesives we used to establish a best practices matrix. For sh*ts and giggles, we included Gorilla Glue epoxy in the testing. Gorilla Glue actually excelled in the strength testing- it beat all of the aerospace epoxies we used. We already knew it did not pass outgassing for use in vacuum, with unknown product controls (being a consumer product), it was just a fun test.
We did not test JB Weld.

jadmt

seems if you looked at your crank before each ride and then again when you completed the ride you should catch any problem before it became a bigger problem.

spelger

that gets old fast.

terrymorse 

Same here, but that was a lifetime ago. I don't think Gorilla Glue existed back then.

Wildwood 

I checked and my Ultegra FC R8000 SC falls just after the last code numbers.

Serious question.
Does that mean Shimano fixed the issue, started using Gorilla glue, or just hasn't seen enough failures yet from late 2019, 2020 and beyond.

jadmt

it would sure be interesting to see some destructive testing on the crank arms of crank arms that fall in the range and crank arms that are later..I doubt anyone wants to ante up the money tho...maybe a youtube person like Hambini would take it on.

PeteHski

Given the failure mode, I’m not sure what this would prove? If there are no current examples of partial debonding in the later units then what will a test prove?

jadmt

it could potentially show what changes were actually made to later units. How do we know there are not/or won't be debonding in later units? seems like shimano denied there was any issues in earlier models for a long time period. it might not prove anything no doubt but it might reveal something.

PeteHski

Yes it could show any design changes that are not visible from non-destructive inspection and testing. But it might not show any differences in the bonding process if there are no mechanical design changes.

Of course we don’t yet know if later units will ever start to fail. Have any failures been reported in these units to date?

CAT7RDR

What is important to me is the company's integrity and my trust in the company producing cranksets or any components that could potentially fail and lead to catastrophic accidents.

I've seen first hand TBI from a bike accident (no the patient did not wear a helmet).
I'm done with Shimano cranksets.

jadmt

at least 1 report that I know of but, face it people who post on forums are really a small percentage of the actual numbers of cranks sold. I ride with 2 different people that have durace cranks and they had no idea of the recall and they are very avid cyclists but don't do forums.
This was copied from another forum.

PeteHski

Well if later units are being reported as failing then it doesn’t look good for Shimano. But it’s hard to tell from individual examples without knowing their history of use and potential abuse.

If I had one of these cranks I wouldn’t freak out over the recall. The reality is that there are literally millions of these cranks in circulation and the failure rate appears to be relatively low and with well used cranks (according to the report linked earlier). But I would use it as a good excuse to upgrade sooner!

mpetry912 

well the quest for ever lower weight means the material in the arms is thin which means a smaller bonding area.

one good curb strike will make it look like that picture above.

No bike component is truly bulletproof (except maybe a Phil bottom bracket or Stronglight A9 headset )

But the trend toward lighter and lighter "race day" components means that those same premium priced components are failure prone and not damage resistant.

/markp

biker222

What is the difference R7000 105 crankset that make it exempt from recall ? I believe they use Hollowtech II for arms.

Maelochs

Apparently they are cast as a single piece, whereas the others are cast in two pieces and bonded together. Separate castings (I would imagine) allow for more precise, and thus lighter and thinner parts, so the upper-end cranks use the more complicated (and in this case, less reliable) two-part construction.

Just guessing.

PeteHski

I tend to agree. It’s a fine line between durability and super light weight. But this does appear to be a specific bonding process issue making the parts more susceptible to failure than they normally would be.

OldForerunner

I have a crankset within the range listed, only two hundred miles on it, still looks brand new.

I'm curious to see how this affects the used market, if at all, since I'd plan on replacing anyway before the Shimano recall (not for any safety considerations, just personal preference).

Maelochs

Pretty sure it is not some "special bonding process" as bonded aluminum monocoques for sports cars are decades old ... probably older for aviation and aerospace.

I am assuming this is "special low-paid Malaysian labor technique" which results in this unique situation.

PeteHski

I think you misread. I didn't say it was a "special bonding process". I said it was a "specific" issue with the bonding process. The report was only speculating what that issue might have been.

Eddy_G 

Shimano 105 R7000 cranks are hollow forged and not bonded.

Rotor Vegast 24 are forged aluminum that has been cnc'd to shave weight, and are fully compatible with Shimano R7000/8000/9000 bottom brackets.

Rotor ALDHU 24 are carbon composite arms and are full compatible with your Shimano BB as well.

The Praxis cranksets will require a Praxis Bottom Bracket, as they are not true 24mm standard, but rather use a GXP-like 24/22 design.

smd4

The Dura Ace 7700 crank arms were made hollow by welding an aluminum plate onto a channel, and polishing everything smooth. This way the arms appear to be solid.

Eddy_G 

In any case, no adhesives are used in the construction of R7000 cranksets, they are forged, they are hollow, and as a finished product each arm has no seams or joints other than the point where the spindle meets the right side crank arm.
Never heard of one failing, at least none that haven't been abused and mis-used.

Perhaps, using old 9-speed as a comparison was an error. R7000 105 is a superior groupset to 7700 Dura-Ace in at least a few categories.

smd4

’Cause it hasn’t more gears? Meh. It definitely isn’t top of the line.

Sy Reene

Campy Centaur?
https://www.tradeinn.com/bikeinn/en/...et/136661619/p

Eddy_G 

More gears. More gear range. stiffer crank arms. The combined weight of cranks and bottom bracket is lighter. More powerful rim brakes. More ergonomic brake hoods/levers. Shorter shift throw. More modern styling.

Not top of the line today, but better than the old stuff nonetheless.

The person I was originally posting to before some folks became sidetracked was asking for suggestions of compatible forged cranksets to replace their R8000 or R9100 arms with.

I stand by my recommendations of R7000 or Rotor 24mm options.