Calibrating the S830 speedometer to Strava

[RicJay]

My setting for the S830 P06 Wheel Size is 28" (by the dealer suggestion.) When on the road the S830 is reading say 20.5 MPH , Strava reads 17.5MPH.
Tires are 700c-40
Anyone have this problem?

 

[RicJay]

The correct setting is 24.4 for the P06 setting for 700C wheels. It now syncs with the Strava readout as well as what the road side radars clock me at.