I have written up one of the weirdest GPS / GNSS related bugs that I've seen to date.

COROS have a nasty bug which results in position and speed data being out of sync with each other, sometimes offset by several minutes. I've seen this boost a friends alphas by 10 knots, during multiple sessions!

This issue should not be confused with the inability of COROS to calculate alphas correctly within their watch / app. This is solely an issue with the files being exported from the COROS app.

I'm just raising it here so that people might recognise the issue if it occurs in their data / friends data. It seems relatively rare, but I've seen this issue evident in tracks from the VERTIX 2 and APEX 2 Pro.

Full description at

Make sure you report these issues to Coros directly at ->