How do you know if your crank is 360 degrees off?

To determine if your crank is 360 degrees off, check the position of the crank relative to the pedals and the corresponding position of the chainring. If the crank is positioned such that the pedals are at the top and bottom dead center simultaneously, it indicates a 360-degree rotation. Additionally, you can use a crank arm alignment tool or check the chain's tension and alignment with the chainring. If the chain is misaligned when the crank is in a given position, it may suggest a misalignment in the crank's rotation.