Take the train
You can quickly access the Willamette Valley Scenic Bikeway from Amtrak at the Salem and Albany stops. The Oregon City Amtrak stop is about 20 miles from Champoeg State Park, the northern terminus of the bikeway. The Eugene stop is about ten miles from the southern terminus of the bikeway.
There are two types of Amtrak trains along the bikeway. The Cascades Train allows for unboxed bikes. You will need to make a reservation for your bicycle to be stored on a bike rack in the cargo part of the train. The Coast Starlight train requires bikes be boxed.
Cascades trains make more stops along the bikeway and even has its own Facebook page the Coast Starlight goes all the way to California.
Amtrak reservations for passengers and bicycle storage space are required. Tandem, recumbent, or other unusual bikes must be boxed. Folding bikes are sometimes allowed as a carry on. For more information, call Amtrak at: 1-800-USA-RAIL (1-800-872-7245) or visit http://www.amtrak.com/bring-your-bicycle-onboard and check out Amtrak's Facebook page