Speed limit drops from 35 to 25 at city limits sign, just before a very steep hill. There is no warning that a steep downgrade is imminent. Gravity immediately accelerates vehicle unless the driver is aware of the hill and slows before downgrade. Motorcycle officers wait under a shade tree and step out into the road to wave motorists over. Depression of grass at the side of the road indicates many vehicles were pulled over. Questionable if radar was actually used. Officer indicated tiny radar unit built into motorcycle just behind handlebars.