When they say "Do you know what speed you were doing" means they haven't a clue and need you to tell them so they can write the ticket. I always say 110kph :-)
I once got pinged for 120kph because he knew I was speeding but by the time he booted up the radar detector I was down to 125kph.
At the time I was actually doing somewhere around 150kph
Worst ticket I ever got was for 160kph overtaking a unmarked car. Though the funniest ever was passing a truck on a hill and then realise he was behind a police car, I blitzed them both and thought F*** it and just kept going.
Though my mate was behind me and the cops pulled him over out of frustration I think and asked him If he knew who the other guy was.
Oh these were on roads limited to 100kph. And when on a bike that can do 150kph in first 100 is bugger all. And no I don't make a habbit of speeding at ridiculous speeds too much on the road, tend to save it for more even surfaces like the track or speedway.
...-Gixer