Coramtb.org has a map of all the trails in the greater Cincinnati area, which included some up your way, though still a bit of a drive. I think the closest to Dayton on their map is Caesar Creek.
And if you just want to do some fitness riding away from cars, the paved trail system around Dayton has gotten really good. See miamivalleytrails.org for a map.
And if you just want to do some fitness riding away from cars, the paved trail system around Dayton has gotten really good. See miamivalleytrails.org for a map.