I don’t know but, just interested for future ref if I ever go to pedal or arm based PM…Does the Rotor INpower have an app where you can change the arm length? If so, try that first then change on the Wahoo app perhaps? IIRC 172.5 to 170 is about 1.5% so keep riding with relative confidence. Report back if you figure it out. For me Wahoo customer service has been hard to get help…good luck!