Originally Posted by
Kontact
Ah, so your comments did not pertain to the newest failure?
Nope.
I admit I hadn't been following this thread
that closely when I posted what I did... the OP's suffered yet another BB failure? Or the joints where other frame components connect to his BB have failed, again? But in some way different than what had been referred to in earlier posts?
Can we perhaps agree that bicycles are engineered to withstand a wide range of fairly well understood stresses during common usage? Also that the OP perhaps represents an extreme case beyond which the engineering constraints of durability are routinely being compromised?
If MRV's seeing
repeated failures in various fabrications at the
same point of frame design my take is that he's routinely subjecting his frames to stresses that are
beyond what those frames' designers and engineers expected their work to have to endure. He's essentially behaving as a destructive testing consort. (Make no mistake here MRV please! This isn't to be taken personally in any way!!)
Originally Posted by
Andrew R Stewart
Perhaps but it's the fork I'm most worried about WRT failure. Every other member of a frame has both ends joined to another member EXCEPT the fork. That poor steerer is a cantilevered beam, even the fork blades are connected at the dropouts via the front axle but that steerer has only wall thickness going for it
Andy.
True enough, and I agree that failure of a fork stands a greater chance of being catastrophic than failure of a BB (keeping this within the boundaries of this thread's title) or the various tubes connected to it. Full loss of one of the only two contact points a bicycle has with the surface it's being ridden upon is something to be avoided. Designers and engineers have had decades of experience that contribute to their better understanding of how frame geometry and materials fabrication can go towards ensuring longevity, where the stresses involved can be quantified.