Portland Road Bike: Wanted - Portland to Coos Bay Route

I'm heading up from Southern Cal to do the Mt. Hood Hoo-ha on Saturday Aug 16th. After that I'm looking for a cycling route to get me from Portland to Coos Bay. I am hoping to do it on my fixed gear, but if there isn't a feasible route to do so, I will take a multipy speed. Any suggestions would be greatly appreciated.........Thanks......Tony