Start at Girdner Trail and head north. A little over a mile down the trail it splits. Take the left in the Y. There is no trail sign here. There are a couple turn offs before the Y, but they all go uphill and dead end shortly after you start on them. Western Civilization continues downhill. Take it easy going down to the creek crossing. The trail is steep and a little hairy is places.
Once at the creek bottom, it's uphill to the Cockscomb Trail. The trail is a grind, but mostly all rideable. Some sections get a little steeper, but it's pretty gradual the whole way up. The climb is worth it as you forget all about it as you take a left on Cockscomb and have a blast going down hill on Aerie.