We have one nice downhill with a pretty straight road and good pavement and a conveniently placed radar speed sign right at the base of the steepest part. On days with a good tailwind I get into a tuck and then sit up so the radar will be sure to 'see' me. Usually it's in the mid to upper 40s, but if I can get up to 50mph or more it switches to flashing "Slow Down."