SB20 - One of my Power Meter Cranks Have Failed. Now What?

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The SB20 smart bike has dual power meters. They work together to give you accurate left:right power measurements.


Here's a dual power meter example with Zwift:
  1. Right Crank measures power and sends it to the Left Crank.
  2. The Left Crank adds its measurements and sends a single message with consolidated L:R data to any connected apps (Zwift in this example).

    Apps like Zwift support a Power Source connection to:

  3. The Stages Bike or
  4. Directly to the left crank.

When both power meters are working correctly, both Power Source connection methods provide similar performance. For more information, see How to Pick a Zwift Power Source.

What if One Crank Fails?

If one cranks fails, the other crank can work independently, when you do the following:
  • Remove the battery from the defective crank. 
  • Use the Stages Bike as the Power source. 

Here's an example with a malfunctioning Left Crank in Zwift.


  1. In this example, Left Crank is malfunctioning. Its battery must be removed and SB20 power must be cycled off/on.
  2. The Right Crank will now automatically connect to the SB20.
  3. The Stages Bike must now be used as the Zwift Power Source. The SB20 will automatically compensate for the missing power meter by doubling readings from the good power meter.

    Note: This method also works for a malfunctioning Right Crank.
You should not notice much difference - if any - with power readings in Zwift. Single-sided power measurement is surprisingly accurate.

What if Both Power Meters Fail?

Things get more complicated when both cranks go bad.  See Both my Power Meter Cranks Failed - Now What? 








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