How does iGS620 /iGS618 alculate elevation /Altitude ?

iGS620 /iGS618 primarily calculates elevation data from a barometric altimeter which measures air pressure.

While air pressure typically provides very accurate elevation measurements, it remains subject to factors  like seasons, temperature, humidity, climate and wind speed at different time.

So it’s common that the absolute altitude values are different.

The relative values as well as the total ascent, total descent and gradient values of the pneumatic altimeter are accurate, which are more helpful for riding.

As with all barometric altimeters, environment changes can cause elevation readings to "drift," even when stationary or riding at on a level path.

To counter environmental elevation drift, barometric altimeters require regular adjustment.

And you can adjust the altitude manually in iGS618, iGS620 and iGS50E.

Steps to adjust the alitude for iGS620 /iGS618

Steps: Setting>system>other setting>set elevation

Why doesn’t iGS620 /iGS618 primarily use GPS to calculate elevation?

GPS elevation is often unreliable due to GPS satellite positioning and coverage.

In testing, we found GPS elevation inaccuracies in hundreds of meters.

Because of this, consistent and accurate elevation data is best achieved using GPS-adjusted barometric altimeter data.