5- Measure between the same two points.
This is L3
The difference between lifting up (L2) and pushing down (L3) is caused by friction. This is called the "Stiction Zone". The greater the Stiction Zone the more friction there is. If it is more than 4 or 5mm the linkage needs attention.
The actual sag is calculated by averaging L2 and L3 and subtracting it from fully extended.
With a Sag Master there is no need to subtract since the tape was locked and zeroed at full extension.
Static sag = L1 - ((L2 - L3)/2)
Note: FREE SAG is the amount the bike compresses with the weight of the bike only - no rider. Use the same method as outlined for Sag.