gksplash wrote: ↑Mon Oct 28, 2024 8:28 pm
I am sorry but as an eng myself, those parts are really poorly designed. Have you ever seen a part with a SF of 1,25. I have in the aero industry but never in commun parts. Blowing those have hapened to all of us.. seat clamp, chainring bolts, stem bolts.. just bad design.
I wouldnt say poorly designed exactly. They did what they could, considering the kcnc one weighs I think only 11 grams. It has an aluminium bolt, but its thick enough. The only real engineering fault is its overconstrained and in bending when tightened really much, as I did. Then, of course it breaks at the start of the threads. Nothing unexpected, its a lightweight part.
The wolftooth ticks all the engineering principles, but its twice the weight.
As for FoS around 1.25, id say it is not so untypical. I consider 25% overload a pretty safe margin if the design envelope is well defined and the weight is a consideration.
Fun fact, sometimes even a below 1.0 safety factor (0.98-0.99) is used (because accumulatively the safety factor of the materials or the fatigue estimates is deemed sufficient)
This is on very rare occasions though and they usually regard strategic advantages against China or Russia