Biking of all flavors exists around Newport.  But if you haven't fat biked a beach, it's one of the best places to ride a "fat bike" anywhere, with miles of beach suitable for all ages.  A "downwind" shuttled ride is fantastic.  Rentals and shuttles are available at Bike Newport, who also support folks on longer bike tours.   A great ride for the family starts at South Beach State Park, winding East to the Yaquina Bay.  Also, Newport is the home of the Oregon Coast Classic mountain bike race on the Wilder Trail System.  You will need a permit, and can get it plus check for logging closures with Bike Newport but the trails are quite close just next to the airport and a brewpub at the trailhead.  Last, options for road biking or casual rides around town abound, literally too numerous to list here.