Yellow Saddle
Guru
- Location
- Loch side.
And much more entertaining than yet another chain wax thesis.
Snapped spindle
- Thread starter roubaixtuesday
- Start date
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And much more entertaining than yet another chain wax thesis.
Ming the Merciless
There is no mercy
- Location
- Inside my skull
Whilst you managed to get that bit right, you got the inner radius incorrect. Hollowtech steel spindles are 3mm thick. Thus the outer radius is 12mm, and inner radius 9mm. Putting real world figures in the calculator, even Olympic Gold medallist torque, you are not going to reach the shear yield point by a factor over 3. A good safety margin.
roubaixtuesday
self serving virtue signaller
Just out of interest, how much does the safety factor improve if the shaft were solid? The hollow shaft with 3mm is only 44% of the weight of a solid shaft. I doubt the strength improves by very much by filling in the centre, but I don't recall the relevant formulae and am far to lazy to look them up.
Ming the Merciless
There is no mercy
- Location
- Inside my skull
A solid shaft of the hollowtech outer diameter has a safety margin of about 4.5 for an Olympic track cyclist.
For us mere mortals in everyday use, the hollow axle far exceeds that safety margin. A safety fsctor of about 9 for a mortals very short sprint.
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roubaixtuesday
self serving virtue signaller
Thanks!
So making it solid would give a a weight increase of ~2.5x for a strength increase of ~1.5x.
Back on the subject of ducks, birds are designed like hollowtech axles. It turns out that some diving ducks are however an exception to the rule that birds have hollow bones, which are assumed to be a modification to reduce weight for flight. The more time spent diving, the less likely to have air filled bones.
One example is the Long-tailed Duck — the deepest diving sea duck — which they found to have thick, marrow-filled bones. This trend is observed amongst many aquatic diving birds because it gives them extra weight to counteract their buoyancy in water, which requires even more energy for diving. In contrast, they found that other ducks, like the Eurasian Teal (a dabbling duck that spends most of its life in the shallows and doesn’t submerge its entire body underwater) have almost entirely air-filled humeri.
https://www.esc.cam.ac.uk/news/some-birds-have-hollow-bones-and-new-research-helps-us-understand-why
So making it solid would give a a weight increase of ~2.5x for a strength increase of ~1.5x.
Back on the subject of ducks, birds are designed like hollowtech axles. It turns out that some diving ducks are however an exception to the rule that birds have hollow bones, which are assumed to be a modification to reduce weight for flight. The more time spent diving, the less likely to have air filled bones.
One example is the Long-tailed Duck — the deepest diving sea duck — which they found to have thick, marrow-filled bones. This trend is observed amongst many aquatic diving birds because it gives them extra weight to counteract their buoyancy in water, which requires even more energy for diving. In contrast, they found that other ducks, like the Eurasian Teal (a dabbling duck that spends most of its life in the shallows and doesn’t submerge its entire body underwater) have almost entirely air-filled humeri.
https://www.esc.cam.ac.uk/news/some-birds-have-hollow-bones-and-new-research-helps-us-understand-why
Ming the Merciless
There is no mercy
- Location
- Inside my skull
Indeed the solid axle duck never got off the ground.
roubaixtuesday
self serving virtue signaller
Hollowduck II for the win
Vapin' Joe
Formerly known as Smokin Joe
- Location
- Bare headed cyclist, Smoker
Campagnolo ducks never break.
Yellow Saddle
Guru
- Location
- Loch side.
But but but...what about Olympian Teals? Safety margin?
Yellow Saddle
Guru
- Location
- Loch side.
They do brake. I've seen it being done.
I was unable to find the inner diameter specification, so I used example cases of 2 (first example) and 1 mm (second example).
Both (of course since percentuages don't change with absolutes, something you ignore(d)) example cases resulted in a 29% better resistence to snap.
Here you make that same "argument", as back then Yellow Saddle did with "Minimal" and "Maximal": a "Good" safety margin.
I then said let's put figures on it, resulting in a 29% better snap resistence, which is Faaaaaaar From Minimal.
This topics declared-as fact is: HollowTech 2 spindles DO snap.
That means that what you here claim as "Good" safety margin was NOT Good ENUF, Nuff' said.
Note again that all I say here is a repeat.
For the Win?
Who did you beat, the Lizards aLong the way?
You Limped Thankfully 3 Flat Miles Home on 1 Leg:
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Fastpedaller
Über Member
- Location
- Norfolk
If it quacks.......
classic33
Leg End Member
It's quackers?
roubaixtuesday
self serving virtue signaller
Another cheeky and lazy question: any idea what the equivalent calc for a solid square taper is?
