To find the starting point for Forest Park, get off of 205 at Highway 30 then go west on Vaughn then Thurman then Aspen. Park near the top and hike or bike past the gate and it's almost immediately pure forest. The flood of green is impressive, especially during a light rain. This service road is Leif Eickson Drive and is open to hikers and bikers (but not motor vehicles), and the hikers and joggers tend to thin out with each mile. The Wildwood Trail parallels up the hill a ways and is open only to hikers. Both follow the contour of of the hillside with hardly any elevation gain. It ends at the Germantown Road eleven miles later.
Vancouver Washington 2006
Forest Park is a forested hillside that stretchs for seven miles on Portland's northwest side. This service road winds for 11 miles along the length of the park, and is remarkably remote in the thick green forest. There's no real challenge to biking it, other than the length.