When the camera is mounted on the handlebars, I place my hand behind the camera and stand in an officious manner while waiting for the green man. If a vehicle is moving quickly, I ‘pan the camera’ on it by moving the handlebars.
I have read some camera owners like to go incognito or are totally discreet. Rightly or wrongly I am choosing to be more obvious about what I am doing. I haven’t had any abuse hurled my way so far.
Neither has the old lady in the press you may have read about. She dresses in high viz and points a hairdryer at speeding vehicles and they slow down.