So I been thinking about that. I have a plan.
One person goes to the north end of the road. Everyone else goes to the south end. With both ends covered with eyes there is very little chance a cop will get on that road without us seeing them, there are not many/any other ways in. So for the sake of explaining this I will be at the north end, and you will be at the south end with everyone else and you will be the 'Starter'.
You call me, and the first rider gets ready. You stand to the side in front of him and get the phone by your mouth with one arm and the other arm in the air and you yell 'Go' at the same time you drop your arm.
I start the timer when I hear 'Go' and rider one goes on the arm drop.
Rider 1 will start with the timer at zero.
You wait 5 minutes and we do it again. At that point though since I have the timer I will warn you that 5 is coming up...then I yell 'Go' at the correct time in the phone and you arm drop on that.....
And so on.......As they get to me I write down the time they arrive at. Obviously we would subtract 5 minutes from Rider 2's time, 10 minutes from Rider 3 and so on.
@Uncle Punk is not invited, he hates speed contests on public roads.