A chain whip, or chain wrench, is a bicycle repair tool. It is used to secure a freewheel or cassette in position while you remove or install the lockring. The tool is equipped with a handle with an attached bicycle chain, so it can grip a cog firmly without slipping.
It’s a handy tool for those who repair bikes at home and bicycle shops when replacing rear cassettes. Endurance athletes who maintain their own bicycles usually have one in their tool collection, particularly if they are swapping cassettes for varying terrain or events.
