Parts of the route are dual sport/Adventure type bike roads. There are also locked gates at the Bull Run reservoir area. I didn't go around them.
I started from Troutdale and did this clockwise. I was detoured at a locked gate into the Bull Run reservoir area. I was able to get back onto to southern part of the route at Brightwood. At the summit of LoLo pass, it turns to gravel. I have 80/20 tires that did fine but a bash plate is advised.
This loop starts/ends in Sandy, OR. Head East from Sandy and cruise up Sleepy Hallow Dr and some National Forest Roads up towards Mt. Hood. Breathtaking views of the mountain and several crossings of the Sandy River and other waterways.
GroovyTimBob