Snapped spindle

[Ratchet Cat]

I’ve always used square taper bottom brackets and had no problems so far.🙈😺🙄

 

[Drago]

I’ve always used square taper bottom brackets and had no problems so far.🙈😺🙄

Did you fit them with a chisel though?

 

[Ratchet Cat]

Nope. I used the proper tools. This thread seems to be going on forever.
Do I need to get a drink and some popcorn?

 

[Webbo2]

Nope. I used the proper tools. This thread seems to be going on forever.
Do I need to get a drink and some popcorn?

You might need a barrel and a corn field.

 

[Drago]

Nope. I used the proper tools.

Ah, a crowbar and acetylene. Very wise.

 

[Ratchet Cat]

Don’t forget the tractor and the rusty spoons.

 

[roubaixtuesday]

Do I need to get a drink and some popcorn?

Hemlock is the only drink to enable escape from here.

 

[Ratchet Cat]

I don’t think our local shop has got any. What about Dandelion and Burdock?

 

[roubaixtuesday]

I don’t think our local shop has got any. What about Dandelion and Burdock?

I would imagine enough of that might have a similar effect. Why not try it and report back?

 

[Dogtrousers]

I broke up a wooden pallet this afternoon using a chisel and a lump hammer. Just saying.

 

[roubaixtuesday]

I broke up a wooden pallet this afternoon using a chisel and a lump hammer. Just saying.

Better than breaking up a relationship with the same...

Yours Jack.

 

[Jameshow]

That

I recently respoked a wheel with a shovel.

That's nothing a built a carbon bike using my JCB...🤣

 

[silva]

Following Silva's example I recently used a mortar to dig over my front garden.

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.

 

[Ming the Merciless]

Chris Hoy at his peak would produce 2,500 watts at 130-135 rpm sprinting round the velodrome. That only comes to 184 Nm of torque. At the more modest outputs of us mortals it will be far less. A typical cyclist peaks no more than 40 Nm

 

[Drago]

That

That's nothing a built a carbon bike using my JCB...🤣

I clean my carbon bike with a custom blended mix of seawater, battery acid, and coca cola.