Im with Frank Zappa on this one, i.e. use of a mirror, when I came back to road cycling, as separate and distinct from my occasional off road ventures I loved it but kept looking at an imaginary rear view mirror so I enquired at the local bike shop and got a helmet mounted one, great but very wobbly, I saw a Cateye one in
Halfords, much more stable image and wider field of view, plus very little need to adjust it all the time.
I do feel very deliverate movements are required, its all about sending non ambigous signals, I do it in cars but on a bike its much easier due to you not being boxed in, a lot of problems arise from dithering and not making your intentions clear.
I also think sometimes, if you give a driver the option to make a dodgy overtake, they take it and regret or werent happy about the maneuver and most seem to prefer being told what to do, I am having primary so you wait and they are freed from the decision of whether to squeeze through, therefore you have saved them that potential dilema.
However, some are just f*cking animals, like the 100 yd stretch where I rode primary through roadworks the other night to avoid debris, cones and some clown overtaking, guess what the clown went for it, little fat Asian bloke with a tache in a manky E series Merc squeezed through, hit the kerb, nearly hit me, blew his horn, brake tested me and then stopped in the traffic, I stopped and the pussy put his locks down, next time perhaps he will realise the sixteen stone six foot snorting dayglo thing may catch up and is actually rather alarming, much more daunting when separated from large Mercedes.....
There was the local gardener who left hooked me, a beardy old drunkard in his pickup turned left in front of me, no indicators, hit the kerb, he goes in my local, might have a quiet word about his alcohol "enhanced" driving.
Otherwise, most drivers have been good for me, few close overtakes but no actual agression but then I do my best to get out of the way and if someone has done me the courtesy of being patient I raise a hand as they go past which I hope they are taking as a thankyou.