Quote Originally Posted by Jen72 View Post
Pedal wrench and Oakleaf:

What is a cassette and where is this little thin washer you are talking about? Thanks in advance.
The cassette is the rear cog cluster. The lock washer is between the cassette and the lock ring, and is actually attached to the lock ring. You'd have to pry it off the lockring to get it out.

http://www.parktool.com/repair/readhowto.asp?id=48