Snapped spindle

[roubaixtuesday]

Chris Hoy at his peak would produce 2,500 watts

Yet it was little known, middle aged me whose torque broke Hollowtech.

IN YOUR FACE, HOY BOY!!!

 

[Paulus]

I did once use a hammer and chisel to undo a corroded locknut on an adjustable bearing cup.
None of this hollowtech technical stuff in my shed though.😁

 

[classic33]

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.

I get it's not for you, but you realise a 1/3 of the posts on this thread are nowt but you complaining, or trying to prove why they're not what you'd use any more. Just find something that works for you.

Fine, don't like them don't use them. But the flogging of the dead horse has to stop sometime.

 

[Yellow Saddle]

Yet it was little known, middle aged me whose torque broke Hollowtech.

IN YOUR FACE, HOY BOY!!!

Yes but how do we know you weren't all juiced up?

 

[Ming the Merciless]

Yes but how do we know you weren't all juiced up?

@roubaixtuesday Is known as the hammer and chisel of cycling.

 

[roubaixtuesday]

@roubaixtuesday Is known as the hammer and chisel of cycling.

I ride for the Camborne school of mines team