Hollowtech Crank

awol

Esteemed Pedelecer
Sep 4, 2013
1,216
374
I know they are called Hollow-tech and the clue maybe in the name but are they supposed to be left "hollow" like this?
DSCN0008.JPG
Or are they supposed to have some sort of plastic bungs in the ends?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,982
8,565
61
West Sx RH
No bung.
 
  • Informative
Reactions: awol

NJS

Pedelecer
Oct 14, 2017
104
28
67
Uk
Oh, will do that.
Thats why I thought there should have been some plastic endcaps with it.
Also, do you leave that plastic screw piece in the left side after tightening the crank arm?
I think plastic end caps would likely trap the moisture in rather than keeping it out.

I can't help on the other question.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,982
8,565
61
West Sx RH
  • Agree
Reactions: EddiePJ

NJS

Pedelecer
Oct 14, 2017
104
28
67
Uk
My first new bike I bought was 5 years ago a Norco 700c, it has hollowtech cranks and I have never done any maintenance like that and they are fine.
I'm pretty sure that Alan Farrina would have said the same right up until the day his sheared.

For the sake of a quick spray inside once a month -- say a £10 can a year -- I'd rather that effort than end up under bus if it let go in traffic.

Maybe he was unlucky, but it doesn't seem to be an isolated incident.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,982
8,565
61
West Sx RH
I'm pretty sure that Alan Farrina would have said the same right up until the day his sheared.

For the sake of a quick spray inside once a month -- say a £10 can a year -- I'd rather that effort than end up under bus if it let go in traffic.

Maybe he was unlucky, but it doesn't seem to be an isolated incident.
Over reaction to a rare occurrence, there are millions of Hollowtech's in use.
Nothing in your link suggesting any major issue or problem.
Any failure is most likely contributed to other factors such accidental damage leading up to a failure, bearing failure or a manufacturing fault.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,982
8,565
61
West Sx RH
£10/year for peace of mind an overreaction. Hm. If you say so.
I do.
We have our own opinions so that is that AFAIAC.
 

Steve UKLSRA

Esteemed Pedelecer
Oct 29, 2015
318
293
Porthmadog
www.ukbusas.org
Oh, will do that.
Also, do you leave that plastic screw piece in the left side after tightening the crank arm?
Yes, that's the preload bolt (1.5Nm) for the BB bearings.
 
  • Informative
Reactions: awol

NJS

Pedelecer
Oct 14, 2017
104
28
67
Uk
Over reaction to a rare occurrence, there are millions of Hollowtech's in use.
Nothing in your link suggesting any major issue or problem.
Any failure is most likely contributed to other factors such accidental damage leading up to a failure, bearing failure or a manufacturing fault.
He's a small sample of hollowtech II failures findable on the web. All separate, all verifiable. Many severe injuries. At least one death.

A small percentage of those is use; and if those odds are acceptable to you, ignore this.

If not, an ounce of prevention just might save you from becoming a statistic.








 

RobF

Esteemed Pedelecer
Sep 22, 2012
4,732
2,312
He's a small sample of hollowtech II failures findable on the web. All separate, all verifiable. Many severe injuries. At least one death.

A small percentage of those is use; and if those odds are acceptable to you, ignore this.

If not, an ounce of prevention just might save you from becoming a statistic.








Hard to see what the user could have been done to prevent those catastrophic failures.

No amount of lube will stop a crank shearing, and even with the broken axles it doesn't looks as if corrosion played any part.

Possible the axle somehow seized, but once again lubing the tube internally wouldn't stop that.
 
  • Agree
Reactions: Nealh and E-Wheels

NJS

Pedelecer
Oct 14, 2017
104
28
67
Uk
No amount of lube will stop a crank shearing, and even with the broken axles it doesn't looks as if corrosion played any part.
Most of those crank failures a shear failures. Shear failures start with stress risers. Rusting causes pitting.

Waxoil is not "lubrication", but rather a rustproofing fluid used to prolong the life of steel. It works by excluding water and air from bare metal and by slowing the progress of existing surface rust using phosphoric acid rust inhibitors.

No rusting, no pitting. No pitting, no stress risers.
 

RobF

Esteemed Pedelecer
Sep 22, 2012
4,732
2,312
Seems to me unlikely painting any fluid on those cranks would have prevented them shearing.

The axle failures are a bit more complicated, but I reckon the tube is simply not strong enough as manufactured to resist the various forces applied to it.

Painting it with something is not going to make it stronger.

Most of Shimano's kit is decent, but the company does have a track record of using buyers to beta test products.

Alfine 11 hubs and eMTB motors are just two examples.

I don't pretend to be a Hollowtech expert, but I bet the latest ones are strong enough to do the job.
 

Advertisers