From the trail description
The remaining 60 miles of the trail is surfaced with packed gravel or cinders with pavement planned for the future. Riders with hybrid and mountain bikes will find the entire trail very enjoyable.
I'm especially interested in hearing from folk that have ridden the unpaved sections.
Also having trouble finding a campground near Big Rapids MI, I prefer this to stealth camping. If you know of one let me know. Closest I can find is Paris MI to the north.