N.H. Rev. Stat. Ann. § 265:143-a

Every driver of a vehicle, when approaching a bicyclist, shall insure the safety and protection of the bicyclist and shall exercise due care by leaving a reasonable and prudent distance between the vehicle and the bicycle. The distance shall be presumed to be reasonable and prudent if it is at least 3 feet when the vehicle is traveling at 30 miles per hour or less, with one additional foot of clearance required for every 10 miles per hour above 30 miles per hour.