Black Ash Mountain is located in the south end of the park on the west side.  Access to the loop is from Tuxedo Station where there is a trailhead parking lot (this still requires a .5 mile walk to the trailhead by road. It is also popular with commuters from NYC that do not have cars.  You can take a train to Tuxedo and walk the road to the trailhead.

From the trail parking lot just over the Ramapo River, walk east on East Village rd, turning to the right.  Walk under Rt 287 then turn left.  The trailhead is about 200 yards up on the right.

This loop can be hiked in either direction.  I always hike in a clockwise direction.  Right where the trail starts from the road, the Ramapo-Dunderberg trail (red dot markings) is straight then makes an immediate right to climb the hill.  Follow this for .25 miles where you reach the Triangle trail (yellow triangle markers).  Stay on the Triangle trail for 2.6 miles.  After this point the trail is shared with the White Bar trail (white markers) for .2 miles.  Here the Triangle trail turns left.  Stay on the White Bar trail for another .2 miles where the trail intersects with the Ramapo-Dunderberg trail.  Turn right on the R-D trail and follow all the way back out to the trailhead.

This trail receives less traffic than other trails and is a good fall hike.