Difference between indoor and outdoor power

I did my long ride indoors and decided to put my outdoor power meter pedals in the Wahoo bike. It turns out there is a difference between them.
Am I right in assuming that is why there is an indoor and outdoor FTP field? So I set them both to a different value then? And if the difference is not linear do I need to adjust zones or not?

Usually your FTP is higher outdoors and your HR is higher indoors for several reasons:

For me it is about 20 watts difference

Another factor at play here: drivetrain loss. Power measured at the pedals will be higher than what is measured at the wheel (wahoobike). Depending on many factors including cleanliness, chain wear, hub age etc.

Thanks for the replies. This is a measurement issue. My wahoo used to be a small percentage lower than the Vector pedals, but now the vector pedals are about 20W lower almost consistently. Trying to troubleshoot further. Still curious to understand if the dual FTP indoor and outdoor option is there to set different values for different devices.

Problem solved. Tightening the pedals up to the right torque and swapping batteries resulted in a 3% difference which is fine given the fact one is a pedal and one is measured on the wheel


20w is a big difference. My tacx and 4iiii crank based are about 7-8w off.