Bobbins have been impact tested to insure they do meet the necessary standard required, we use high tensile steel bolts that are designed to bend and not break.
The video below shows a 50 kg weighted bar dropped from a height of 1.1 metres, this resulting in the high tensile bolt bending and not breaking off.
Bobbin has slight impact mark, more than capable of withstanding this force......
https://www.youtube.com/watch?v=4BHtWJ4bSQ0