There are plenty of places to ride your bike within the park but I don't recall any bike paths just the main roads.
The only bike path is the 3 mile path that runs between Westport Light State Park and the Westport Docks area. As far as Grayland Beach State Park there are no bike paths just country roads. Across the highway to the east you can bike through the back roads of Grayland past cranberry bogs. Harvest will be starting any day now.
Thanks! Your answer is awaiting moderation.