because his frame most likely does not have a bashplate, there is nothing to protect the bottom of his frame.
if you have 1 bashring, then it will have some protection, but 1 side of the bbshell can still get damaged.
if you have 2 bashrings, then it will give even more protection....
did you even thing before you posted that
you put more force on them though pedaling forwards, but not as much backwards.