The trails can be quite rooty, and steep, at times. Most are rolling, somewhat wide, but spread out well also. Steepest doable climb is 20%!
Rt. 20 in Sudbury, MA, travel west to a left turn on Brimstone Lane. Park in parking lot at bottom. Pedal 1.2 miles on pavement to top of Nobscot Mtn. The trails are from the top.
http://www.singletracks.com/item.php?c=1&i=864