From the organizer's website: Bikes, bridges and free admission to the Bite of Oregon afterwards are in store for the annual Providence Bridge Pedal and Stride. Since 1996, this is the only opportunity each year to enjoy the Willamette River bridges – including the top decks of the Fremont and Marquam bridges – from the best possible vantage point: the seat of a bicycle. Avid cyclists and novice pedalers, young and old, savor this opportunity. With bike rides from 3 to 36 miles, as well as a five-mile walk, the event offers choices appropriate for everyone.
Start time and location is variable depending on which route you chose. More details on their website: