This is a rail-to-trail paved bike path. 12.5 miles is one way. It ends at the Withlacoochie River. A worthwhile ride if you're ever in the area.
In Madison, Fl. on Hwy 145 (East Livingston St). Trail begins on right side of road heading North.
http://www.singletracks.com/item.php?c=1&i=5206