Cecily and I are planning to ride the Tarbell Loop in SW Washington. We'll meet at the Gateway Transit Center at 8:00 as well. Or you can meet us at the Rock Creek Campground at 9:00. This will be an intermediate to advanced ride due to length and amount of climbing.
See you there.
Jordan

http://www.oregonlive.com/cycling/index.ssf/2008/06/cyclists_find_lots_to_love_on.html

From the Oregonian:

Approximately 22 to 25 mile loop.  Begins with a six-mile strenuous climb then is a mix of rolling hills, and some short climbs.  There is a section of baby heads and some larger rock to traverse on a fast and reasonably steep descent.  This is not a beginners ride.  You need solid skills and at least moderate aerobic capacity.
 

If you ride in any of these areas please fill out this survey. It only takes a few minutes will help determine the future of these popular and close to Portland trails. Tell them that you mountain bike and that you enjoy these public trails.

http://www.dnr.wa.gov/RecreationEducation/Events/Pages/amp_rec_western_yacolt_burn_survey.aspx

Jordan