Seaside [1] has a bumper crop of places that rent bicycles, skates, and surreys, all for similar rates, about $10 per hour for a bike. The Prom Bike Shop (622 12th Ave., 503/738-8251) is a full-service bike shop; rent cruisers or novelty bikes at Wheel Fun Rentals Spoke 1 (21 N. Columbia St., 503/717-4337), Wheel Fun Rentals Spoke 2 (151 Ave. A, 503/738-7212), or Iron Coach Bike Rentals (220 S. Columbia St., 503/738-9458).
Links:
[1] http://www.moon.com/destinations/oregon/north-coast/seaside