If you were to judge by the comment section alone, you might think that roughly eighty percent of all carbon fiber cranks ever sold have also sheared in half. You might also get the impression that it was only thanks to the good graces of whoever's running our simulation that those riders, with $800 splinters embedded deep into one leg, didn't also perish from fatal fiber poisoning that claims one in every ten weight weenies.
With those cold, hard facts staring you in the face, do you really want to risk your life to save half the grams that a relaxed visit to the loo can eject? And why am I thinking to myself that I should just save even more weight by doing both?
Sure, while that's all puffed up beyond reality, a certain Huck to Flat video
recently had many riders sharing their experiences with broken carbon cranks. And by "many," what I really mean is way more than I would have expected. It's certainly not limited to a single brand or two, either, with failures being reported across completely different designs and even seen very publicly under one of the quickest World Cup racers
Unfortunately, it's often difficult to narrow down the precise cause of the failure after it's happened, as we discovered. Is the root origin of your crank's failure a rock strike, or were they just not durable enough? The answer is probably yes, but also maybe probably. Point is, anything can break if you try hard enough, and thirty seconds on the Google reveals scores of failed aluminum bits, so it's not like carbon has the exclusive monopoly on trail-side failures.
Even so, it's painfully obvious that carbon fiber isn't the ideal material to be dragging through pointy rocks at speed, isn't it?