Why must the drive chain slack be measured and adjusted while a motorcycle is on its side stand (or as specified by the manufacturer), rather than on a paddock stand that lifts the swingarm directly?

1. Because swingarm compression changes the distance between the drive sprocket and the rear sprocket
2. Because paddock stands twist the frame slightly, affecting alignment
3. To ensure the rear brake caliper is completely unloaded
4. To prevent oil from leaking out of the output shaft seal