PowerTap Joule GPS User Guide - Manual (Page 21)

Joule GPS User Guide page 21
TIP: The accuracy of any power meter is dependent on many variables, especially temperature. Fluctuations in temperature
affect the internal strain gauges, which can alter the reported torque value. This is significant as power is calculated from
torque. The PowerTap Auto Zero feature continually adjusts the calibration of your device, compensating, in real time, for
environmental factors like temperature, assuring that you have the most accurate power data throughout your ride.
Power Sensor
Activate Sensor
Start Pairing
Name
Power2
Sensor ID
2484
Circumference, mm
2096
Auto Zero
On/Off
Delete Sensor
Manual Zero
Back to Bike
9:34
A
CHAPTER 4: SENSORS
CALIBRATION, AUTO and MANUAL ZERO
There are many environmental factors that can affect the accuracy of a power meter. Temperature, humidity, and circuit
resistance are part of the measurement, but none of them remains constant while riding. The continued accuracy of a power
meter depends on its ability to take these changes into account. Auto-zero recalibrates the power meter over and over during a
ride to keep the measurements from drifting. Use the Auto or Manual Zero options in the Power Sensor screen to calibrate your
power meter, assuring you are getting the most accurate power data at all times.
Power2
Manual Zero
Torque RAW
Torque Offset
Firmware Version
45
Back to Sensor
9:34
A Auto Zero
Manual Zero
On or Off. Typically, always On. The Auto Zero
function follows the same steps outlined for
Manual Zero but does it continually during the
ride, whenever the bike is coasting for 4 or
more seconds. If your bike is a fixed-geared
or track bicycle you may consider turning
Auto Zero off.
Calibrating or “zeroing the torque” refers to the
process of resetting the Torque Offset value of
the physical torque tube (where the internal
strain guages actually measure wheel torque).
1) Make sure the power meter is awake and
communicating with the Joule GPS. Make sure
the bike is still, with absolutely no pressure
on the pedals or tension in the chain.
2) Select Manual Zero on Power Sensor screen.
The Calbration screen will appear. Torque
RAW should be 0. The last saved Torque
Offset is displayed. The value is typically
500-524 in-lbs.
3) Select Manual Zero on Calibration Screen.
The Torque Offset value will update with the
torque tube calibration value, given the
current environmental conditions.