How can I remove a stuck rear cassette? I've been trying in vain to remove a rear cassette that I myself installed about a year ago.  I may have over-tightened the lock ring and now I can't remove it no matter what position I hold the wheel-chain whip-wrench combination.  Any advice on what to do to get this cassette off (short of going to my LBS)?  The wheel is relatively new and the cassette is very new, and the reason I want to remove the cassette is to replace a broken spoke.
Have you tried holding your tool like this: 



I have just discovered it (instead of the classical "one tool per hand" technique) and it helped a lot.