Tannery Knobs gives Johnson City a proper outdoor playground almost in the middle of town. The trail system folds around a wooded ridge above downtown, with purpose-built mountain-bike routes that range from beginner-friendly loops to faster, more technical lines.
It is a good pick if you want an active half day without driving deep into the Appalachians. Bring your own bike or check local rental options before you go, and expect the trails to feel more like a compact bike park than a wilderness ride.