Do you put more tension on the belt to avoid this?
You can either put more tension on the belt or put an idler pulley so that it makes the pulley engaged with the belt more.
i usually use 14t 9mm, no slipping as long there is less than a few mm of give when you press down with a finger lightly. high tension here is big on efficiency.
also if something is miss alined that can cause slipping on hard braking…
Where did you buy from your 14T pulley from? I’m having a hard time trying to get one.
from diy sometime last year.