Chain Whip

A chain whip is a tool that will often be included in a decent bike tool kit. As the name implies it has a long handle with a length of chain at the end. It is used as a way to grip the cogs of a cassette allowing you to gain enough tourque to loosen a lockring. Some older cassettes require the use of two chain whips applied in apposing directions to loosen the smallest cog of the cassette which itself acts as a lockring. Unfortunately there are no real alternatives to a chain whip since using anything else will likely screw up the cogs on your cassette. Luckly if you have screw on type cassette a chain whip is unnecessary.