Chugach National Forest is an amazing 5.6 million acres and has over 200 miles of trails, mostly on the Kenai peninsula. The longest is the Resurrection Trail System which includes the Resurrection Pass Trail, the Resurrection River Trail, and part of the Russian Lakes trail.

• Alaska Backcountry Bike Tours
• Alaska All Season Cycling has an Introduction to Mountain Biking in Alaska
• On and off-road biking in the Denali Highway area
• The Arctic Bicycle Club in Anchorage
• All about the Iditasport 'ultra-race'.
• (See also this article by Dave Inwood)
• GPS Trail Maps around Alaska
• maps of Alaska

more links:
http://www.nearpointpress.com/NPP_Links.htm
more bike shops:
http://www.nearpointpress.com/Bikeshopsrev.htm