New to biking?  Need to revamp what's in your pack?  Here are some basics that all riders should bring on every ride.  Be independant on the trails so you or your ride buddies don't have to walk out due to a mechanical.  Knowing what to bring and how to use it will ensure that few rides are ruined by a simple mechanical problem, riders running out of water, or bonking. 

Also, check out your local bike shop or bike club and learn the basics of caring for your bike, changing tires and fixing a trail.  In the Seattle area, REI, Cascade Bike Club, and Evergreen Mountain Bike Alliance regularly host and/or post maintenance classes.

http://www.cascade.org/community/Classes.cfm - Shows links to many local resources for bike maintenance classes
http://www.rei.com/map/store - Find a Store and watch Events for maintenance classes
http://evergreenmtb.org/home/index.php - Watch the ride calendar for maintenance classes

Basics to bring on every ride:

CLOTHING

   TOOLS

•   Spare tube
•   Tire levers
•   Multi-tool for most of the bolts & adjustments on your bike
•   Pump or CO2 cartridges  (know how to use it)

    FIRSTAID

• Basic First Aid Kid (in zip-lock bag) including Bandaids, Ibuprofen, Tums, Benadry

Depending on the distance of the ride and it's location, your "What to Bring" list should get longer.  For more information, check the Evergreen Mountain Bike Alliance website.  If you are riding more than a few miles away from civilization, bring an expanded list of items and more water.  The what to bring page at Evergreen shows "basics" (for rides less than 5 miles away from civilization), "serious" (for rides more than 5 miles from civilization), and "prepared for anything" for epic/backcountry rides.