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How to zero your power meter

How to Zero Your Power Meter

When it comes to power meters, a cyclists’ first concern is usually accuracy – and rightly so. After all, what’s the point of measuring power if the data isn’t true and reliable? Most of what makes a power meter accurate is outside of our control. How it was designed, engineered and assembled all contribute to a power meter’s accuracy. However, there is one thing every cyclist can do to aid in the accuracy of their power meter. It’s easy and only takes a few seconds. Perform regular zero-offsets. For most power meters, they should be performed before every ride. This article aims to address what zero-offsetting is, why it’s important and how to zero your power meter depending on which one you have.

how to zero your power meter

 

Calibration and Zero-Offset

While the terms calibration and zero-offset are often used interchangeably, they are in fact two separate, distinct procedures. Calibration refers to a one-time procedure the manufacturer performs when your power meter is assembled. Specifically, the manufacturer sets the ‘slope’ of your power meter. Your power meter uses the slope to determine the correct wattage output when you ride.

Zero-offsetting or zeroing, is a procedure that is performed by the cyclist before every ride. When you do a zero-offset, the power meter zeros out any residual torque that has built up in the power meter from previous rides, temperature changes or installations. In essence, zeroing wipes the power meter clean. Think of zeroing as setting the tare on a scale. You wouldn’t step on a scale if it was reading 10 lbs. with nothing on it. Nor should you just hop on your bike and ride without performing a quick zero-offset.

 

General Zero Procedures

While the steps taken to zero each power meter vary slightly, the general process is the same.

  1. When you perform a zero, you should be off of the bike. The pedals should be completely unweighted
  2. On your bicycle computer, navigate to the calibration page and select Calibrate. (Again, you’re really zero-offsetting but most bicycle computers call it Calibrate)
  3. Most computers will then display some type of “Calibration Successful” message

Also, here are two helpful tips to keep in mind if you run into issues when zeroing your power meter:

  1. Be sure you have the latest version of firmware installed on both your head unit and power meter. This can help avoid issues during the calibration process
  2. If you have any ANT+ compatible devices paired with your head unit that aren’t currently in use (heart rate monitor, speed/cadence sensor, etc.), you can try disabling them on your head unit. Sometimes, the head unit will continue to search for these before proceeding to the calibration procedure

 

How to Zero Your Power Meter: Steps for Each Power Meter

Based on which power meter you have, please find the corresponding steps below which will outline how to zero your power meter correctly.

Image of the 4iiii Innovations logo

4iiii Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically with the left arm in the 6 o’clock position
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should see the two digit code “10” and a “Calibration Successful” message
Image of Assioma logo

Assioma Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically (at 6 and 12 o’clock)
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful 0” (It’s important the value is 0. If not, repeat the calibration procedure again)
Easton Race Face company logos

Easton | Race Face Zero-Offset Steps

When:

It is not necessary to perform a zero-offset before every ride. However it is recommended to zero-offset the power meter periodically in order to ensure maximum accuracy. In addition, a zero-offset is recommended after changes to the crank such as changing pedals, chainrings, installation of the crank, tightening of bolts, etc.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically with the left arm in the 6 o’clock position
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful”
Image of the FSA logo

FSA Zero-Offset Steps

When:

Never.

The PowerBox has Auto Zero, a feature that performs an automatic zero-offset every time you coast for at least two seconds during a ride. Therefore, while it is still possible to perform a zero using the head unit, it really is not necessary. Just get on your bike and ride, the PowerBox will do the rest!

Image of the Garmin logo

Garmin Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Position the cranks in a horizontal position (3 and 9 o’clock)
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful”

Important Note:

The Vector 3 comes with an auto-zero function. Auto-zero can be enabled or disabled using your bicycle computer. When enabled, the Vector pedals will auto-zero every time they are woken up. The pedals will also do an auto-zero immediately before going to sleep (four minutes after the last movement). Note that in order for auto-zero to succeed, the pedals must be stationary for approximately 10 seconds and the bike must be upright.

Even with auto-zero enabled, you can still perform a manual zero at any time (the steps outlined above). In fact, upon installing the pedals for the first time or moving them between bikes, it is recommended you perform a manual zero in order to get the offset values into a range where the auto-zero can track any further changes.

Pioneer Logo

Pioneer Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically with the right arm in the 6 o’clock position
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful”
Image of the PowerTap logo

PowerTap P1 Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. On your bicycle computer, navigate to the calibration page and select Calibrate
  3. You should receive a message saying “Calibration Successful”. The head unit might also include a number in the calibration successful message like 5 or 20. This number refers to the zero offset value and isn’t something you need to worry much about

PowerTap G3 Hub Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the hub
  2. On your bicycle computer, navigate to the calibration page and select Calibrate
  3. You should receive a message saying “Calibration Successful”
  4. Note that the G3 Hub will self auto-zero while coasting – which will help keep it calibrated at all times

PowerTap C1 Chainring Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. On your bicycle computer, navigate to the calibration page and select Calibrate
  3. You should receive a message saying “Calibration Successful”
  4. Note that the C1 Chainring will self auto-zero while coasting – which will help keep it calibrated at all times
Image of the ROTOR logo

ROTOR 2INpower/INpower DM Zero-Offset Steps

When:

The 2INpower and INpower DM power meters do not need to be zero’d before every ride. However, you should perform a zero-offset after the initial installation or after changing any drivetrain components (pedals, chainrings, etc.). It is also recommended that you perform a zero-offset after 30 hours of riding.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter. (Note that with some head units, you need to apply a load to the crank and pedal a few times before entering the calibration menu)
  2. Align the crank arms vertically with the left arm in the 6 o’clock position
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful 1000”
  5. Slowly turn the crank counterclockwise two or three turns and align the crank arms vertically again with the left arm in the 6 o’clock position and right arm in the 12 o’clock position
  6. Calibrate once again and record the offset value shown
  7. You can repeat the process if necessary to ensure numbers are in the same range (+/-200)
Image of the SRM logo

SRM Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. On your bicycle computer, navigate to the calibration page and press Set
  3. The screen displays the current zero-offset and the previously stored zero-offset
  4. Once the current zero-offset value remains stable for a few seconds, press Set again
  5. You have set the zero-offset and both numbers should now have the same value
Image of the Stages Cycling logo

Stages Cycling Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically with the left arm in the 6 o’clock position
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful 850”

The 850 number refers to your zero-offset value. Note we are using this number as an example. Your offset-value might be above or below this, and that is fine. The absolute value of the number is not something you need to worry about. Just make sure it doesn’t change drastically from one calibration to another.

You can also perform a zero-offset using the StagesPower app on your mobile device.

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically with the left arm in the 6 o’clock position
  3. Open up the StagesPower app on your mobile device and select “Connect via Bluetooth” on the iOS app or select the power meter from the list of Discoverable devices on the Android App
  4. Select “Zero Reset” from the app. A zero reset value will appear under “ADC” once the process is complete
Image of Velocomp logo

Velocomp Zero-Offset Steps

When:

The first time you ride outdoors only.

Steps:

  1. With the light on the PowerPod yellow, press the button on the top of the PowerPod
  2. You then perform a 5-minute ride during which point the PowerPod will calibrate. Ideally, aim for a steady ride with minimal stops or interruptions
  3. During the ride, the light will flash yellow, indicating that the calibration procedure is in progress. You will also see the watts on your head unit increase from 1 to 100. (The number indicates the % complete. So at 50 for example, your head unit is saying the calibration procedure is 50% complete.)
  4. After 5 minutes, you should reach 100, at which point the calibration process is complete and your actual power will begin to show
  5. Click the button on the PowerPod again
  6. The light should flash green
  7. Begin pedaling and the light should turn solid green
Image of the Verve Cycling logo

Verve InfoCrank Zero-Offset Steps

When:

Never.

The InfoCrank does not need to be zero’d. The reason for zeroing a power meter is to zero or cancel out any residual torque that has built up in the power meter from previous rides, temperature changes or installations. The InfoCrank was constructed and designed so that torque never accumulates in the strain gauges. The InfoCrank reads true and accurate 100% of the time – no zeroing necessary. It is a ‘get on and go’ power meter. We do recommend performing a zero in the event of a crash however.

Steps:

  1. Align the crank arms vertically (at 6 and 12 o’clock)
  2. Place the chain on the smallest chainring
  3. On your bicycle computer, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful 0”
  5. Repeat the process as necessary until the calibration reading goes to 0
Image of the WATTEAM logo

WATTEAM Zero-Offset Steps

When:

Before every ride.

Steps:

  1. Spin the cranks backwards a few times to wake up the power meter
  2. Align the crank arms vertically with the left arm in the 6 o’clock position
  3. On your bicycle computer or smart phone, navigate to the calibration page and select Calibrate
  4. You should receive a message saying “Calibration Successful”
Josh Matthew

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