This is one of the best rides I've been on in Montana. My favorite kind of riding is fast, flowy downhill so this was right up my alley. The trail is just over 3 miles up and ~2 miles down. The total elevation gain is about 1,800 ft. The descent is one-way downhill so you can really drop the hammer -- no need to worry about bikers/hikers coming up. They built a couple smallish jumps and a bunch of banked turns --- makes for an extremely fast downhill. This is a blast to ride!
Head South on S 19th Rd from Bozeman. Take a left on Nash Rd and then a right on S 3rd Rd. This will eventually dead-end at the Leverich Canyon trailhead.
http://www.singletracks.com/item.php?c=1&i=3983