What's your top speed?

Wrong. It IS possible to set them off.

BMMF and I both set one off on the drop down into Brighton on one of the forum rides (when 50x14 made his debut perhaps?).

speed cameras need to have a reflective surface to bounce off of, so it's not a definate that you will; set off a speed camera on a bike.

So Hippy rides around with a mirror on his back? Interesting, no doubt so riders left in his screaming wake are forced to witness their own looks of tortured pain as he leaves them for dust.....or something like that anyway.