Did a local ride today and recorded it with my new Garmin Edge Explore. When I stopped the ride it said 2001’, though there were quite a few times on the ride when I was climbing and the ascent total wasn’t increasing on the display which I thought was odd (and annoying) - at least 3 times that might have totalled a few hundred feet at a guess. When it uploaded to Strava that said 2350’-ish. Is that likely to be more accurate, given the times it wasn’t adding height? Surprised and not quite sure what to make of it TBH...
Both my garmins seem to be random number generators when it comes to climbs so I just correct it once it is uploaded to Strava. It may not be perfect but I assume that it is better to go of the topographical data then what garmin has made up.
IME the figure on the garmin at the end o of the ride is usually good.
My edge always gives 1200m for a local loop which is basically 3x sea level to 350m climbs, plus a bit of undulation.
Upload it to strava and it’s similar. Click “correct elevation” (ie override barometric data with local mapping) and it gifts me 50% more climbing.
I believe Garmin use air pressure to calculate elevation.
On a nice, still day, mine (fenix 3) is bang on. On a changeable or stormy day, it is all over the place.
So take Garmin’s with a pinch of salt. I prefer Strava’s anyway 😉
Similar issue on Lezyne, use Strava elevation correction.
I've got an edge explore - it's got no barometer, so you're relying on GPS for elevation which is crap for vertical measurement. I reckon mine under measures by around 30-40%. Great unit in every other way.
The Strava correction will be way more accurate!
I believe Garmin use air pressure to calculate elevation.
Some do, some don't.
The Edge Explore, as mentioned above, does not have a barometric altimeter, it relies on GPS for elevation (which is crap) and then corrects in Strava. The data that it gives to Strava will have info in it regarding elevation and how it was acquired and Strava applies different corrections accordingly.
My GPS in very cold or wet weather occasionally massively under-reads the elevation - possibly the barometric altimeter port has got water or ice in it - but it always corrects back in Strava.
If you Google Strava and height, you should find an article they posted. Height gain is fraught with issues such as not many confirmed height references, minor GPS deviation etc. They use some clever methods to try and correct it, such as using other riders data and the heat map to work out the correct height, and whether you are riding on top of a cliff, or 10 metres to the left and 100 metres down at the bottom of the cliff!
Strava altitude numbers will be pretty accurate if you're just going straight up a hill but all over the place when you are contouring. As spooky says, it's all to do with the granularity of altitude data.
If you think your Garmin with barometric pressure has had a wobbly, your can click 'correct elevation' on your activity and it will recalculate using the basemap.
Strava Height Article
https://support.strava.com/hc/en-us/articles/216919447-Elevation-for-Your-Activity?mobile_site=true
Ultimately who knows how much you have really climbed? Roads are never completely flat, so who knows what a few feet here and there mean in terms of the real vertical distance travelled. Whenever I’ve been on a group ride people’s elevation records are always different, unlike distance travelled. Treat any figure with a pinch of salt & don’t get too concerned about it.
100% what he says^^
It's incredibly difficult to calculate ascent gained due to GPS margin for error/inaccuracies etc. Pick one and use it as a yardstick by all means, but don't assume it's accurate. I tend to use Strava's measurement for this, for no other reason than I don't really look at Garmin connect once uploaded.
Garmin uses a barometer and needs calibration to be accurate and even then it can vary during a ride (I leave home above sea level and often return 100ft or so below).
GPS altitude alone is very poor.
Corrected data via Strava or Garmin Connect works on topographical elevation data but this is an average within square areas and on a mountain bike in particular there may be much variation within that square.
None of it is perfect. Key thing for me is consistency. Though it's mostly just a curiosity.