Incorrect Total Ascent on Garmin Edge 820 after latest update

I recently noticed this problem: while the altimeter is working fine, showing the correct altitude, the Total Ascent of the ride is very incorrect. It's adding up much slowly than it is supposed to be, or not adding up at all on some steep sections. At the end of the ride, the Total Ascent is much lower than it is supposed to be.

For example, after climbing from 700 meters to 1700 meters altitude, with some small descents in between, the Total Ascent was obviously supposed to be minimum 1000 meters, but it was only around 600 meters. The Total Ascent for the whole ride was 800 meters, while my friends had 1400-1500 meters (they also have Garmin Edge, 820, 530, probably without the latest update). The same day, another ride with some steep climbs, same problem.


I think it's because of the latest update...


Please fix ASAP, this is totally wrong. 

  • Just to add another voice, I have 11.20 installed and my total ascent is, at a minimum, 10% lower than my buddies or the Strave corrected ascent.  Would be nice to have it fixed...

  • Hy guys, i have the same problem, i would like downgrade  the firmware, where can i find the firmware 11.00? currently in the Garmin web site i see only the 11.20

    thanks in advance.

  • I just spent some time with technical support and changed my GPS from GPS +Galileo to GPS + Glonass.  Glonass has been around longer (thanks mother Russia).  I also deleted the data file inside my GPS folder on my Garmin.  Finally, a 10 second hold of the power button and will leave the device outside for 10 minutes for the device to create a new GPS connection.  Fingers crossed.  If it works, I'll come back to the group.

    To change GPS to +Glonass

    https://www8.garmin.com/manuals/webhelp/edge820/EN-US/GUID-A867FC6C-71B2-4E42-8FA5-98568D8705D3.html

    To reset the device

    https://www8.garmin.com/manuals/webhelp/edge820/EN-US/GUID-46A06A7C-1F46-4DBA-B010-DAD7BA6BE59E.html


  • Hello,

    Is there any progress on this topic ? Is 12.10 correcting such problem ?

    I also had this issue 3 or 4 times - a correct start but after some time the altitude does not evolve as expected.

    I don't see correlation with GPS+ GLO or GPS + GAL.

    Once, I covered the baro hole to prevent rain to stub it, and got no issue - any link ???

  • i just picked up a used 820 and have done a couple rides using my old 510 and iphone as well just to see how they recorded. the 820 shows significantly less elevation and distance. i sure hope they fix this with the next update. it's really disappointing.

  • same here garmin edge 820, fw 12.3. calculatet total ascent is about 10-20% too low since update last year. altitude is measured correct. why is garmin still not able to fix this issue, this is unacceptable.

  • I’m using a garmin 820, system 12.30 and am experiencing similar issues.
    For example as I was riding up a long climb I was looking at Both my ELEVATION and my TOTAL ASCENT on my garmin and they didn’t seem to be in sync. So I took a 6 photos of my garmin which showed my elevation and my total Ascent along the ride once I noticed the issue.
    You would think that if plotted against one another, the slope would be Unity, 1, as long as there were no downhill sections. I.e. A change in ELEVATION in a section of road would equate to a change in TOTAL ASCENT .
    That’s not quite what I found.  My slope was 1.13!  with an R2 = 0.9995!!
    Since both the elevation and the Ascent are both calculated in the Garmin, I don’t know how this could happen.  
    Any ideas?  This may be why I get underestimates of Ascent, that can be fixed by Strava!

  • A difference in elevation is obtained by subtracting one value from another single value.  Ascent is calculated by the Edge by adding every positive increment. along the path, so I expect they'd differ.  IDK how they factor in GPS vs baro measurements between those.  What do you get when you turn on elevation corrections in GC?

  • I disagree, as my route was monotonically upward, the difference in elevation and ascent should be identical unless there is a systematic error. Since my data was taken over more than 1000’ of climbing, I figure there is a systematic error of 13%.
    And According to Garmin support: " The elevation correction within Garmin Connect is only intended for use with those device that do not contain a barometric altimeter"

  • Ideally, it'd be perfect, and maybe it should be better than it is, but noise on successive elevation readings could be both relatively positive and negative and the positive differences would be summed.  Think about a perfectly level ride where there's no change in elevation and no ascent.  Noise in the instantaneous elevation readings will show a zigzag in elevation around the nominal and could lead to a positive ascent accumulating, even though there was none.  The mechanism I'm describing would always lead to an Ascent greater or equal to the positive elevation change.  I agree at 13% over a monotonic slope is a lot, and it should be better, but I'm not surprised they're different because how they're arrived at is different.