I assume you're referring to the backside of Barker / Locke / White Cap.  It has shitty exposure, doesn't hold snow and is pretty rocky.  Also, there are some sudden drops with flat landings and trees.  You can get mangled back there.  Not to mention the hike back up sucks, unless you plan on skinning down to one of the logging roads and heading out to Airport road near Big Adventure.  Don't get me wrong, you can have some fun back there.  There are better places to ride at the river.