Ionic GPS underestimates distance while biking

[jknorvik]

Today I went four times around a course that is 2.97 miles.  The total distance is 11.88 miles but the Iconic GPS showed 10.70 miles only, which about 10% less.  It also underestimates the distance when I run or walk but by about 4% less.  Any know fixes to this?

Moderator edit: Updated subject for clarity 

[SilviaFitbit]

It's great to see you on the Community @jknorvik. Thanks for the details that you've mentioned. 

At least 24 GPS satellites are constantly in orbit around the Earth and broadcasting data. All GPS devices, whether your phone or a Fitbit device, require a direct path to these satellites in order to receive their radio transmissions. If the signal is blocked—either because you're underground, near many tall buildings, or as a result of atmospheric effects—GPS won't work. While GPS gives you a more accurate measure of distance than step counting alone, the actual accuracy depends on both your environment and the weather.

If the GPS signal is lost, your phone or Fitbit device continually searches for a GPS signal as long as an exercise is in progress.

Note that when you track an exercise with GPS, both GPS and accelerometer data are used to calculate the distance shown in your Fitbit app. 

I'll be around if you need further assistance.