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Zero Offset Calibration
The Power Meter spigot contains load cells which are used to measure the force being applied to the paddle.
The output of a load cell when the shaft is experiencing no force is referred to as the Zero Offset. Each load cell has an associated zero offset.
There are two load cells on a Power Meter. The load cells have been designated channels N and O
The Zero Offset of a load cell can drift a small amount with a change in temperature. This is why manufacturers of power meters typically recommend performing a Zero Offset calibration on a semi-regular basis.
A typical Zero Offset will change no more than 5 units between calibrations. A difference of 10 or more is an indication that either a bending force is being applied to the shaft, that there is an issue with that particular channel or that you recently traveled from an extremely hot or cold climate.
After performing a number of Zero Offset calibrations, it will quickly become clear how frequently or infrequently a Zero Offset calibration is required.
If the Zero Offsets vary by no more than five between calibrations, then there is little to be gained from performing a calibration regularly.