Originally Posted by
devildogmech
I had the bike upside down on a picknic bench at school.
It's best to make drivetrain adjustments with the bike right side up. If you don't have access to a bicycle workstand try to find a secure way to hang the bike upright. Even then some adjustments need to be made to fit riding conditions. Gravity, torque, and flex all effect drivetrain adjustments more or less.
Another free source for mechanical adjustment advice is
http://www.parktool.com.
Al