I tend to ride the same routes over and use my garmin 810 to record the ride. Until the last few rides the elevation gain on the same routes used to be very close to one another.
Now during the last few rides, for some reason the elevation data is approximately 30% less than on the same previous rides. So say the elevation gain was previously a consistent (ish) 650m, its now saying 405m!!
Anyone have an idea whats happened to my garmin??
Nope, sorry. I once dived to 66,000 feet below sea level on one ride in Wales. Don't know if that helps put things in perspective?
Barometer in them. Difference in pressure can change it, even during a ride (I often end up higher/lower at the end of a long loop than when I started). Also, blocked vents might mess with it.
It's not accurate anyway unless you calibrate it by setting known locations and heights. Even then I think it only works on the start location, or seems to on my 510. Hence the aforementioned long loop issue as it corrects it at the start, but doesn't at the end, for the same location).
Other thing is if you're looking at Strava or Garmin Connect, check it's not set to overriding the Garmin and using topographical data instead. Strava will favour the device if it knows it has a barometer but you can disable that. Garmin Connect you can turn it on and off to see the difference.
As above, try blowing in the little holes underneath (rain does a great job of blocking them), and set the altitude of your 'home' location .
I'd disagree that they are inaccurate. I live at sea level, a nd my 520 records around 1000m for my (extended) commute, which is two passes of a 380m* hill, a 150m* hill and a bit of undulation.
*according to the map
Ill have a look on the pc to see if its using topo data instead of the barometer data for elevation. Something has happened in the last few weeks as it was consistent before, even if it was consistently wrong.
Ill have a look to see if the holes need cleaning as well.
Thanks
bob_summers - Member
I'd disagree that they are inaccurate
They can be accurate, but they need calibrating and as I say it seems it only calibrates to the start, or mine does. Considering that pilots have to constantly calibrate theirs based on conditions, especially for long flights.
My last ride, same location, calibrated to the start at 70ft and finished in the same spot at -40ft.
Though I'm not that fussed. Main thing is the elevation gain, and I find the Garmin clocks higher gain than Strava's topographical data so makes me look like I've done more serious climbing 😀