What do you say to the rozzers when you get stopped for something petty?

What reason did they give for the search? They're only allowed to perform a search if they have reason to believe you're carrying something to commit the crime they're accusing you of (i.e. not justified for cycling on the pavement), or if there was a crime in the vicinity that you were being searched in relation to. By law, they're required to tell you why this is necessary.

Otherwise it's just an abuse of powers.

I suspect the latter...

I'm unfortunately ripe for a section 44 so I can't get away with shit. I once got pulled over at the train station and had my car searched on a section 44. When I asked him why me, he said my car was too loud. How the fuck is that related to a section 44!?