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What Is Power Meter Scaling?

As the seasons grows colder, many riders head indoors to stay on top of training. With smart trainers becoming more popular, a growing number of riders are experiencing power discrepancies between the power meter they use outside and their smart trainer. Because watts are being measured from two different locations (their on-bike power meter and the trainer), power data can look different between the two sources. Here we will explain what power meter scaling is and how it can be helpful to adjust the differences.

 

Power Scaling

Also referred to as slope adjustment, power scaling is the ability to manually change (using your power meter app) the wattage seen on a bike computer. Your power meter app essentially does this by changing a constant in the equation used to determine wattage. Wattage numbers are the torque you put into the pedal stroke multiplied by cadence. To get a readable wattage number, a multiplier constant is used. Therefore, you can use power scaling to help reduce the differences between power meters and smart trainers.

 

Why Would This Be Needed?

Two power meters may not give the exact same wattage and therefore, a rider may want to adjust one to match the other so training numbers can remain comparable. This can be helpful for those training for races or providing data to their coaches. Riders wanting a deeper dive into why two power meters might read differently can read our FAQ which explains this: Why are my power meters reading differently?

 

How To Adjust Your Power Slope

Many, but not all, power meters will allow riders to adjust the slope value in their app. Adjusting the slope higher will provide a higher power number while lowering the slope will provide lower power numbers. Howevern, if you adjust your power meter to match your indoor trainer, we recommend making sure you reset your power slope when it’s time to ride outside again.

 

Can I Adjust the Slope on My Power Meter?

Many manufacturers allow for the power slope to be adjusted. Below is information on which manufacturers offer this option.

Power Meter BrandsAdjustable Slope?
4iiiiYes
FaveroYes
GarminYes
LOOKNo
MageneYes
power2maxYes
QuarqYes
ROTORNo
ShimanoYes
SigeyiYes
StagesNo
SRMNo
Dave Harris

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