We need to arm the bikes with crowbars, not to actually use but if someone comes up to your car window wielding a crowbar you listen to, and remember them 
Alternatively, have an airzound wired up to a parking sensor, if they're within 3ft of your handlebars, they get a blast... Simple

Alternatively, have an airzound wired up to a parking sensor, if they're within 3ft of your handlebars, they get a blast... Simple
