While they’re busy loading your bike, hop into their driver’s seat. If you’re lucky, maybe they left the keys in the ignition, free car! If not, either surprise the fuck out of them and ask “Where are we going?”, or call the law, or just beat the shit out of them, your choice.
OP here, and I hear ya.
Still, if it was me, and I actually wanted to hurt them (if they were riding off and not loading it in their trunk as my post regards)…
I (probably) wouldn’t hurt them directly, I’d probably jam a stick or pipe in the spokes. Like fuckit, it’s my bike, I installed all the spokes myself and can install more later if necessary. And I know my bike’s serial number by heart.
I can’t help it if the thief busts his face on the pavement because I damaged my own property…