The trail has a lot of everything, slow technical tight areas, fast downhill, extremely bumpy uphill, flat and smooth. I usually ride this trail every night after work, takes me about an hour, but i don't ride the whole singletrack.
From Green Bay take 41/141 North to Exit 176 Sunset Beach Road. At the bottom of the ramp take a left. Go about 2.42 miles and take a right onto Reforestation Road. Go about 1.51 miles down Reforestation Road until you see the NEW ZOO on the right, and parking on the left. You will need a different pass to ride these trails, this is not a state trail. If you go into the NEW Zoo visitor center you can get more information there. I believe it is $3 daily and $15 annual.
http://www.singletracks.com/item.php?c=1&i=3117