Gradient errors

My gradient is always a degree or 2 less than the actual gradient. Overall the elevation gain and loss over the ride is accurate.
I wonder if it has to do with the orientation of the head unit which I hav tilted up so that I can see it better. Will try levelling it and se if it makes a difference?

0 Luko79 6 days ago

the Grade% is faulty, the device is on my desk and showing this: (usually the same -1,-2,-3% on flat section outside) , Edge 840, 28.33 (but i assume it is the same on every Edge devices x40/x50/MTB...)

youtube.com/.../Wiqk8xUjmtQ

0 scarboroughjohn 1 day ago

So I tried it out and changing the orientation of the device makes no difference. Today riding down a hill showing -3 to -4%, riding up the same hill anything from 0 mostly 1 and peaked at 2%. Definitely incorrect, seems universal on all Edges?