Disclaimer: We're not lawyers. This page is to share the laws with you so you can make your own interpretations. We also outline what we've gathered from our experiences.
“Public nudity” is legal in Oregon, with a few obvious exceptions. See ORS 163.465. However, Portland has adopted a stricter “indecent exposure” law, 14A.40.030, which overrides Oregon's “public nudity” law within Portland city limits. Basically, if you're in a visibly turgid state, or are otherwise notably “indecent,” you may be committing a crime.
In 2008, Judge Jerome LaBarre of Portland, Oregon ruled that riding naked is a legally protected form of free speech. This ruling came about after a cyclist was arrested for riding naked on Alberta Street in Portland during a Last Thursday event in June (not during the WNBR). Although he bore no painted slogans and was not handing out leaflets, the judge dismissed the case because riding naked is “A 'well-established tradition' in Portland, and understood as a form of 'symbolic protest'.” See the story on BikePortland.org or OregonLive.com.
Therefore, it is highly unlikely you will be cited for public nudity on the World Naked Bike Ride, but you can still be cited or arrested for other crimes such as disturbing the peace or obstructing traffic.
The Portland Police Bureau are allies of the World Naked Bike Ride. They are there to help the ride go smoothly. They won't hassle you unless you do something in addition to riding naked to call attention to yourself. You should obey traffic laws, not ride while intoxicated, have a white headlight, a red tail light or reflector, and otherwise not be a jerk.
Putting it another way: If you get arrested for anything, it probably won't be for indecent exposure. They'll probably call it disturbing the peace or obstructing traffic. But if you're just riding naked, you're probably safe.
Neither Shift nor the event organizers are responsible for anything you do. You are. Riding naked in Portland is legal. Please respect the ride, other riders, the Police and yourself. This is officially a “bare as you dare” ride, so make your own choice about how naked you want to be. If you want to blow through a red light, or otherwise do something illegal, that is also your choice and your risk. We can't stop you. (Although various entities like, say, a big truck *can* stop you, and that might not be entirely comfortable.)