I guess it depends if you mean Josh Bender levels of real mountain biking. I’m 90kg and fairly confident that I’m not going to do anything gnarr enough to break them. I am firmly a tyres on the ground type of rider though.
I went for the flat ones in the end – arrived today and look lovely – can’t try them out for a while due to broken bones but look pretty decent, especially for the money!
Think twice before ordering from Planet X .. ordered the bars, which seem ok. Half of my order hasn’t turned up though, even after chasing them multiple times!