Snapped spindle

[Ming the Merciless]

Hmm, more than double it to 100 Nm. Still no twist and this is 628 watts at 60 rpm. No one put at those watts at such a low cadence, in reality shear stress less, angle of twist still zero..

 

[Ming the Merciless]

Finally Chris Hoy. Still aint twisting Hollowtech, angle of twist zero. Shear stress of an Olympic Gold medallist is 1/29th of what you came up with

 

[silva]

Just a quack one @silva - could I confirm you've never actually fitted a hollowtech2 BB/chainset?
(The OP 'snapped' the spindle of one of this type.)

As said earlier here, and also elsewhere on this forum in past times:

...
Your last sentence then, it wasn't my "opinion", it was my "experience".
The only plus I experienced, also already said here and elsewhere on the forum, from Hollow Technology, was the chainring centering of Hollow Technology version Hollow Technology 2: on the bike used before my avatar bike, and used while the latter was on repair, the tension variation of the chain was near to nil (remember, case singlespeed). But its bearings failed after 5 years, and the Octalink version of Hollow Technology, failed for me due to that loosening crank, that inflicted me near accidents upon (re)discovery, and dozens if not hundred of stops along the road to check the -*--bolt.
There's only one word for such: CRAP, and I used it, Mister fossyant.
...

It was the bike I used before the avatar bike.
I purchased it with a singlespeed drivetrain.
But reoccurring annoyant freewheeling in both directions with the freewheel, trying other brands/models (upto triple the price, with more pallets, and (better) seales) to no avail, decided to let it convert to a fixed gear.
First this HT2 bike, then also the 1 year older square taper bike.
I never had a bottom bracket/bearing failing before, with a bike typically used a decade, the HT2 one was the first fail, it was after 5 years. Despite bigger bearings made possible by the HT2 change to outside shell.
1 explanation could be that the plus of the bigger was undone by the min of the less protected due to outside shell.
I rode all weather (no choice - work), rain, mud, ...
I mounted various shielding for the chain, but the low sitting bottom bracket is hard to shield.
The Octalink 1 story with the avatar bike was similar to the freewheel and HollowTech 2 stories: it's always water that scraps them.
Water in the freewheel > sticky grease > springs too weak to move pallets back.
Water in the freewheel > frost > springs freeze in position.
Water in the HollowTech 2 bearing > rust > fail
Water in the Octalink 1 spindle left > "lubricates" the pressfit to loose > left crank falls off. I made a solution for it: I mounted a cover above the left cranks mount, rubbersealed and tied in place. Since, the left crank never came loose anymore.
But since my frame had to be replaced, and thus everything disassembled, I decided to not risk Octalink anymore, it had been a test (chain tension variation), and the test had failed anyway, so not any reason to keep it.

Above has all been said here on the forum, over the years.
In my view this spindle break should never occur, this spindle is to transfer leg power, not a spindle of a wheel that might be overloaded due to a bump over a pothole or so. Hence also the torsion cause of the break.

 

[roubaixtuesday]

As said earlier here, and also elsewhere on this forum in past times:

It was the bike I used before the avatar bike.
I purchased it with a singlespeed drivetrain.
But reoccurring annoyant freewheeling in both directions with the freewheel, trying other brands/models (upto triple the price, with more pallets, and (better) seales) to no avail, decided to let it convert to a fixed gear.
First this HT2 bike, then also the 1 year older square taper bike.
I never had a bottom bracket/bearing failing before, with a bike typically used a decade, the HT2 one was the first fail, it was after 5 years. Despite bigger bearings made possible by the HT2 change to outside shell.
1 explanation could be that the plus of the bigger was undone by the min of the less protected due to outside shell.
I rode all weather (no choice - work), rain, mud, ...
I mounted various shielding for the chain, but the low sitting bottom bracket is hard to shield.
The Octalink 1 story with the avatar bike was similar to the freewheel and HollowTech 2 stories: it's always water that scraps them.
Water in the freewheel > sticky grease > springs too weak to move pallets back.
Water in the freewheel > frost > springs freeze in position.
Water in the HollowTech 2 bearing > rust > fail
Water in the Octalink 1 spindle left > "lubricates" the pressfit to loose > left crank falls off. I made a solution for it: I mounted a cover above the left cranks mount, rubbersealed and tied in place. Since, the left crank never came loose anymore.
But since my frame had to be replaced, and thus everything disassembled, I decided to not risk Octalink anymore, it had been a test (chain tension variation), and the test had failed anyway, so not any reason to keep it.

Above has all been said here on the forum, over the years.
In my view this spindle break should never occur, this spindle is to transfer leg power, not a spindle of a wheel that might be overloaded due to a bump over a pothole or so. Hence also the torsion cause of the break.

This is very similar to the issues the barnacle goose has with its webbed feet, I think.

 

[silva]

Hmm, more than double it to 100 Nm. Still no twist and this is 628 watts at 60 rpm. No one put at those watts at such a low cadence, in reality shear stress less, angle of twist still zero..

View attachment 799409

Because you filled in an spindle diameter twice, quadruple, ten times HT2's and decided to keep it outside your picture, in order to jest a Don't Know Nothing?

This was my second example, with HT2 spindle diameter entered:

Following Silva's earlier example I filled in the as documented actual figure for the HollowTech 2 spindles diameter:

https://amesweb.info/Torsion/torsion-of-shaft-calculator.aspx
Selected "Hollow shaft"
Filled again in some rough bicycle alike values.
HollowTech axle diameter is documented as 24 mm.

Torque [T] 500
Rotation speed [ω] 60 rpm
Shaft outer radius [c2] 12 mm
Shaft inner radius [c1] 11 mm
Shaft length [L] 100
Modulus of rigidity [G] 300 GPa
= 1 mm wall thickness
RESULTS:
Maximum shear stress [τmax] 626.697 MPa
Angle of twist [θ] 0.997°

Torque [T] 500
Rotation speed [ω] 60 rpm
Shaft outer radius [c2] 12 mm
Shaft inner radius [c1] 10.5 mm
Shaft length [L] 100
Modulus of rigidity [G] 300 GPa
= 1.5 mm wall thickness
RESULTS:
Maximum shear stress [τmax] 445.14 MPa
Angle of twist [θ] 0.708°

Maximum shear stress difference is 626.697-445.14 = 181.557
That's 29% less stress in the material.
29% more reserve to avoid a snap, by a 1.5 mm instead of 1 mm thick wall.
The weight "penalty" is:
https://www.profilebendingmachine.com/steel-pipe-tube-hss-weight-calculator/
24 mm outer diameter, wall thickness 1 mm
Result: 60 gram
24 mm outer diameter, wall thickness 1.5 mm
Result: 80 gram

So, for the HollowTech 2 spindle (outer)diameter specification of 24 mm,
Increasing a wall thickness case of 1 mm to 1.5 mm (=+50% thickness)
- gains 29% more resistance to torsion-snapping (=Good For Safety)
- gains 33% more weight (=Bad For Cheating in Races - the "extra" is 20 gram.
Yes, this Spindle Snap Safety +29% increase is Priced as 20 gram, but at the Counter they Complain to the Cashier because the lesser cheating might cost them 3 sec on 3 km and come in second...

... just to illustrate the rather big difference in priority between a cheat-racer and a commuter/shopper that happily wants to trade that 3 sec for no spindle snap.

Spindle wall thickness 1 mm: Angle of twist [θ] 0.997°
Spindle wall thickness 1.5 mm: Angle of twist [θ] 0.708°
The wall +0.5 mm decreases the angle of twist from 0.997° to 0.708°, that's 29% smaller.
That is that same 29% of my "gains 29% more resistance to torsion-snapping" above, Mister Ming the Hmmm I Don't Know Nothing Merciless.

 

[Webbo2]

Did Silva get jilted by one of the Shimano family. 🤷🏼‍♂️

 

[Ming the Merciless]

Because you filled in an spindle diameter twice, quadruple, ten times HT2's and decided to keep it outside your picture, in order to jest a Don't Know Nothing?

Nope. I put real world torque figures into the calculator. You know, figures that cyclists actually produce. Dont come near your figures, no need for extra material to handle 500 Nm.

I also put in the real outer and inner radius of 12mm and 9mm. The steel axles are 3mm thick not 1mm as you put in.

The axles are operating 6-7 times within their shear yield limit. I would say that is pretty safe.

 

[silva]

This is very similar to the issues the barnacle goose has with its webbed feet, I think.

Well no, these issues are the ones of the Light Religion Lotsa Bucks for Little Plus, be sure. Including freewheels, 6 instead of 3 pawls OHNO All That Weight! Sealing instead of no sealing OHNO...
Of course, cost cutting, By Big Coincidence, is the same direction.

 

[roubaixtuesday]

Well no, these issues are the ones of the Light Religion Lotsa Bucks for Little Plus, be sure. Including freewheels, 6 instead of 3 pawls OHNO All That Weight! Sealing instead of no sealing OHNO...
Of course, cost cutting, By Big Coincidence, is the same direction.

Ah, more your Egyptian than barnacle goose. Fair enough, my mistake.

 

[classic33]

Well no, these issues are the ones of the Light Religion Lotsa Bucks for Little Plus, be sure. Including freewheels, 6 instead of 3 pawls OHNO All That Weight! Sealing instead of no sealing OHNO...
Of course, cost cutting, By Big Coincidence, is the same direction.

Poor or no maintenance doesn't help things either.
Something else for you to consider, before replying again.

 

[silva]

Because you filled in an spindle diameter twice, quadruple, ten times HT2's and decided to keep it outside your picture, in order to jest a Don't Know Nothing?....

Nope. I put real world torque figures into the calculator. You know, figures that cyclists actually produce. Dont come near your figures, no need for extra material to handle 500 Nm.

There you went again denying what I wasn't asked - I asked "spindle diameter", you deny is "torque figures".

Because you filled in an spindle diameter twice, quadruple, ten times HT2's and decided to keep it outside your picture, in order to jest a Don't Know Nothing?

This was my second example, with HT2 spindle diameter entered:

Spindle wall thickness 1 mm: Angle of twist [θ] 0.997°
Spindle wall thickness 1.5 mm: Angle of twist [θ] 0.708°
The wall +0.5 mm decreases the angle of twist from 0.997° to 0.708°, that's 29% smaller.
That is that same 29% of my "gains 29% more resistance to torsion-snapping" above, Mister Ming the Hmmm I Don't Know Nothing Merciless.

The HollowTech 2 spindle diameter is 24 mm.
If you make it ten times to 240 mm, or a hundred times to 2400 mm, you pre-draw a small dinosaur and a big dinosaur to break it.
That is what you did in your "hunt" for a denial.

For this HT2 diameter, the stress resistance (and formula-implicit the angle of twist) decreases with 29% if wall thickness is increased from 1 to 1.5 mm (to the inside of course).
29% better to resist snapping.
I compared along the "Maximum shear stress" parameter.
You compared along the "Angle of twist" parameter.
It doesn't matter - both give the same comparison result of 29%.
Regardless force, since on both sides of the equation and thus to eliminate in the comparison.

 

[silva]

Poor or no maintenance doesn't help things either.
Something else for you to consider, before replying again.

Well no, just the Light Religion that Surfs on the Edge of Safety.

 

[Dogtrousers]

This thread is a work of art

Dada