Lower section of 39 before the bridge at SG reservoir has narrow or no shoulder, guard rails and high speed traffic, very sketchy. After the reservoir, traffic is light and the shoulder wider. Really hot in Summer, often slight headwind. Fantastic views start at about halfway point. Water tap next to road at Coldbrook campground. No water at hwy 2 end point. 2 mile detour to Crystal Lake campground for more water and market for snacks. My preferred option to avoid traffic on lower 39 is to start on GMR (Glendora Mt Rd) and connect to 39 via E Fork Rd. Section above Crystal Lake junction has unmaintained surface. 25's or 28 tubeless with lower pressures a good idea.