Originally Posted by WhyFi

Manufacturers are able to make such thin seat stays because they're not doing a lot of the heavy lifting. See Steven Kruijswijk's Cervelo: he crashed and then finished a TdF stage without noticing that he'd completely lost one of his seatstays -




Just riding around isn't going to stress that area enough to cause that kind of damage. An impact, like from a branch swept in to the wheel, is more likely to cause the type of damage seen on your 'stays. Knowing this explains why Spec "dragged their feet."