Originally Posted by
lowlife1975
not surprising given how many people out there buy carbon seatposts w/o a torque wrench and just tighten the hell out of them. 9/10 bikes i see, the seat post collar turned the wrong way too, which tends to lead to pinches-> cracks -> failure.
i'm sure there are bona fide cases of tightening the post to spec and still having failure but more often the post has probably been overtorqued some point in its life.
Right on. The plastics have some nice properties but they are prone to fatigue cracking, impact cracking and the most common is quoted above. You can't squeeze this stuff.
Besides that, unlike metals, when plastics fail there's no warning. Looks perfectly good one moment and then BAM!, complete failure.