 The trail is well known among area mountain biking enthusiasts for its rolling terrain which makes for fast, smooth rides although there are portions requiring technical skills.The portion of the trail that sees the most mountain biking activity starts near the end of Michael Faraday Court, behind SkateQuest-Reston ice skating rink and follows the tributary stream valley to Lake Fairfax.From Lake Fairfax the trail crosses over Hunter Mill Road and follows Difficult Run itself all the way to Great Falls Park.