This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
Bicycles are permitted on Interstate highways in Oregon. ODOT's bicycling policy permits cycling on the shoulders of most rural Interstate segments in Oregon (notably much of I-5, I-84 and I-82) where no reasonable alternative exists. Specific urban segments, the Portland metro area, and certain bridges are signed prohibited; always confirm against ODOT's bicycling-on-Oregon-highways guidance before riding.
What this means in practice
Interstate cycling is legal in Oregon, but ride only where you have a wide, clean shoulder and exit at the first signed bicycle exit when conditions deteriorate.