Snapped spindle

Page may contain affiliate links. Please see terms for details.

silva

Über Member
Location
Belgium
The only tools an artisan needs to work on bottom brackets

View attachment 798958

That's what I saw the dealer using to get the drive side out.
It worked, and without doing damage.
The chisels handgrip was round, he put the head on the axles side, and hammered it further deeper.
But, as told you several times by now, you're self-made argument is based on full or zero power with nothing inbetween while looking at tv... what you made of my "hammer and chisel".
 

silva

Über Member
Location
Belgium
Ah, thanks. Yes I've seen his bike is transport and it breaks a lot. I suspect it's the user not looking after it, but if he's also prolific back home on forums........

I'll get my mate to log in that's an ex pro and lives out there these days. Does loads and loads of miles on hollowtech cranks.
The break of the frame tube bottom bracket to drive side rear wheel mount with a slot in it for belt application, has nothing to do with the crankset or spindle.
It's not because the Cat Crabbed the Curtain, that the Dog Dropped the Donut.
 
OP
OP
R

roubaixtuesday

self serving virtue signaller
https://amesweb.info/Torsion/torsion-of-shaft-calculator.aspx
Filled in, for what it matters, just some rough bicycle alike values.

Torque [T] 500
Rotation speed [ω] 60 rpm
Shaft outer radius [c2] 28 mm
Shaft inner radius [c1] 26 mm
Shaft length [L] 100
Modulus of rigidity [G] 300 GPa
= 2 mm wall thickness
Results
Parameter Value
Maximum shear stress [τmax] 56.524
Angle of twist [θ] 0.001
Power requirement [P] 3141.593
Polar moment of inertia [J] 247683.165

Torque [T] 500
Rotation speed [ω] 60 rpm
Shaft outer radius [c2] 28 mm
Shaft inner radius [c1] 25 mm
Shaft length [L] 100
Modulus of rigidity [G] 300 GPa
= 3 mm wall thickness
Maximum shear stress [τmax] 39.783
Angle of twist [θ] 0
Power requirement [P] 3141.593
Polar moment of inertia [J] 351907.072

Maximum shear stress difference is 56.524-39.783 = 16.741
That's 30% less (what you call "minimal") stress for a 50% thicker (what you call "maximal") wall.

Formulas are more accurate than minimal, maximum, and Believe.

Very poor to only include 5 significant figures in some of your calcs. The full 9 used for part moment of inertia is far superior. That's 10,000 times more accurate, which is much better.

Inaccuracy costs lives!
 

Ming the Merciless

There is no mercy
Location
Inside my skull
But, as told you several times by now, you're self-made argument

You are the one who got upset when told that I can remove my HT2 cranks only using an Allen key. Rather dented your needing expensive tools for the job argument. Then later above, you claimed you agreed all along an Allen key is all that is necessary.

Answer this. Why did your dealer use a hammer and chisel to remove a HT2 BB, rather than the correct tool for the job? Plus what model of HT2 cranks did you have fitted?
 

Ming the Merciless

There is no mercy
Location
Inside my skull
Ah, of course. I wondered why my bike exploded!

Depleted uranium everywhere 😮
 

silva

Über Member
Location
Belgium
Very poor to only include 5 significant figures in some of your calcs. The full 9 used for part moment of inertia is far superior. That's 10,000 times more accurate, which is much better.

Inaccuracy costs lives!
Very poor to only include 5 significant figures in some of your calcs. The full 9 used for part moment of inertia is far superior. That's 10,000 times more accurate, which is much better.

Inaccuracy costs lives!
Repeat: 50% increase of thickness of hollow axle's wall (to 30% stress reduction
https://amesweb.info/Torsion/torsion-of-shaft-calculator.aspx
Filled in, for what it matters, just some rough bicycle alike values.

Torque [T] 500
Rotation speed [ω] 60 rpm
Shaft outer radius [c2] 28 mm
Shaft inner radius [c1] 26 mm
Shaft length [L] 100
Modulus of rigidity [G] 300 GPa
= 2 mm wall thickness
Results
Parameter Value
Maximum shear stress [τmax] 56.524
Angle of twist [θ] 0.001
Power requirement [P] 3141.593
Polar moment of inertia [J] 247683.165

Torque [T] 500
Rotation speed [ω] 60 rpm
Shaft outer radius [c2] 28 mm
Shaft inner radius [c1] 25 mm
Shaft length [L] 100
Modulus of rigidity [G] 300 GPa
= 3 mm wall thickness
Maximum shear stress [τmax] 39.783
Angle of twist [θ] 0
Power requirement [P] 3141.593
Polar moment of inertia [J] 351907.072

Maximum shear stress difference is 56.524-39.783 = 16.741
That's 30% less (what you call "minimal") stress for a 50% thicker (what you call "maximal") wall.

Formulas are more accurate than minimal, maximum, and Believe.
That is pretty clear
For an hollow axle with that radius, a wall thickness increase from 2 mm to 3 mm = +50%, decreases the stress in the material by 30%.
30% better resisting breaking.
30% is not "minimal", that is (near to) 0%.
50% is not "maximal", that is (near to) 100%
You complain here about "accuracy", while that as "minimal" declared, is 30 whole units off, and that as "maximum" declared, is 50 whole units off.
That's like adjusting the crosshair of the scope while you hold the rifle backwards. ;)
 
Top Bottom