Pinkney State Rec Area and the Patowanami Trail 14 miles of single track for bikes its a really good trail.  Herritage Park in Adrian has trails too but can be overgrown. At one point they had some features like small jumps and ladders.  I grew up in Jackson and lived in Toledo so I would say those are your best bets.   Ella Sharp Park in Jackson has some trails too but they are kind of pieced together sections but if you don't mind exploring.   

People don't realize how great Charlotte is for trails.  Up there you have to work to find anything to ride.