How to Rotafix:
Rotafix is a technique for tightening or loosening a cog without a chain whip.
Why Roafix? Because standard chain whips do not fit 1/8” cogs, and you get the mechanical advantage of the entire wheel for tightening.
When performing a rotafix, wrap a rag around the bottom bracket shell to protect the paint on your frame from being damaged by the chain.