When i did my cbt, my instructor was adamant about " owning your lane", basically meaning to keep central as much as possible, on my second ride on my own bike, i had some twat up my arse, so i slowed down and held him back, always checking my mirrors to see what he was doing, then when he backed off, i resumed normal speed , i won't allow anyone to try and intimidate me, and if i did get a nudge i'll just leave it there To be honest this isnt smart. Brake checking someone can cause serious incident or even a gradual slowdown can cause them to get frustrated. Last thing you want is an emotional driver behind you.