5- Measure between the same two points.
This is L3
The difference between lifting up (L2) and pushing down (L3) is caused by friction. I call this 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.