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Best AnswerWithout the phone, your Blaze has no access to a GPS, therefore it will have to rely on the stride setting. This will need to be done on the profile settings
Instructions can be found here.
@Greypower as Rich stated you need to set stride, however you can only set one stride length for running. Therefore distance calculation will be off if you run at different paces from the stride you enter into Fitbit. The basic issue is that the Blaze w/o phone GPS is essentially just a pedometer, counting steps, and then calculating distance based on the running stride you entered in Fitbit profile.
Aria, Fitbit MobileTrack on iOS. Previous: Flex, Force, Surge, Blaze