Karen Lingel’s answer to “Why is it easier to balance on a moving bike than a non-moving one?” (http://www.straightdope.com/mailbag/mangularmo.html) is wrong. Research back in the 1970s showed that gyroscopic forces are not important.
There’s a good discussion with references at http://physics.about.com/library/weekly/aa050900a.htm
Karen has now (4 July 2002) revised her Staff Report; here is the link to the revision: “Why is it easier to balance on a moving bike than on a nonmoving one?” – CK Dexter Haven