I am by far an expert of knowledge here but I am sure you will find plenty of trails to keep you busy at 2 different locations near Bryson City:

Tsali

http://www.mtbikewnc.com/trailheads/tsali.html

Fontana

http://www.fontanavillage.com/


Depending on you and your son's ability there are a ton of options...we really do have it all here!!! Enjoy!!!