Originally Posted by
Steve B.
Why do I have this thought that Strava doesn't use the fit file, instead uses the actual GPS track. That could explain the miles shortage (cutting the corners)
From everything I've read, the Wahoo companion app syncs the FIT file from the Bolt to the phone and sends the file to Strava and whatever authorized site you have set up. To send the data, it would have to convert the file and send it in GPX, TCX or KML format, which are pretty big files and will use up more data. The FIT file size for today's 60 mile ride is only 505KB compared to the same ride file in TCX format which is 8.79MB. I'm not 100% sure what the FIT file actually contains as I have not found a suitable free or shareware FIT file editor so I can actually see the file contents.