The recommended speed is 20km's over the speed that the vechicles are traveling... (from a multitude of sources), most of us are comfortable with 30 - 40 km's over... much more than that is IMO stupid.
I have had car doors opened in front of me, pedestrians running through traffic, etc, and I have managed to miss all these obstacles... I have however seen other riders not quite miss...
Thank you, I'll stay riding at my pace and the suicidal idiots can just wait behind till I can safely move over for them...