I suppose most of us think about what it would be like to go up that road. But then I began to wonder what it would be like coming down - on a motorbyke or a bicycle.

You'd want to know that your brakes are in good order and be very careful about getting too deep into a corner before braking. Any sort of slip up could be lethal. (I suppose if you think like that you just shouldn't do the ride.)
Near me, Macquarie Pass is a favorite with bikers (8km of tight turns but no great gradient) but this totally puts it in the shade.