howdy, not sure if anyone has noticed that they are picking up more vertical metres recorded after going to the k-edge Garmin mount (or similar).
I noticed this after i was doing more (sometimes 20-30%) vertical metres than other people doing the exact same ride (they would also be within a few metres of each other) and started trying to get to the bottom of it.
I gave my Garmin 500 a clean and still nothing so through I process of elimination I worked out I was the only rider with a Garmin extended mount. So I decided to go through my old Strava files and I can see I picked up the extra altitude on some of my standard runs after installing the k-edge. I also noticed a 'spikier' altitude graph on Strava, my old graphs and other peoples graphs looked quite ‘smooth’.
I assume as its sitting out there at the front of the bike with nothing blocking the altimeter intake it must being picking up more accurate(?) or more often altitude changes.
Anyway , I do love my k-edge (kidding myself it looks pro) so not going to change using it but just wondering if anyone else has noticed anything similar?
A mate and I did the same ride on the weekend. I had about 739m and he had 950. he used a K-Edge mount with an Edge 800. When he told Strava to auto correct, it came back closer to my reading.
My 500 seems to short change me in terms of elevation in comparison to the 'corrected' figures. Just had Strava correct the elevation on my ride last Thursday up Montacute & over Lofty and it changed from 800 odd metres worth of climbing to 1,129m.
I seem to remeber there being a fairly significant discrepancy between the corrected & recorded figures when I did the Dirty Dozen too.
You shoudln't need to do the correction on an Edge 500 (or above) as they have barometric altimeters. Unless the air pressure at sea level changes dramatically during your ride then the barometric altimeters should give an accurate total amount of vertical metres climbed. You can set the altitude of any number of waypoints on your Garmin (take the altitude off a topo map) so when you start your ride it will reset the altitude to the waypoint you are at.
The correction is really there for devices that rely on the GPS to try and estimate altitude (which it does very poorly). The correction works by running your GPS track over a 3D elevation model of the terrain and then calculating the total elevation gained. This only works well if the 3D elevation model is any good (in topographically complex places like the Adelaide Hills this may not be true) and if your GPS track is good enough that its not constantly wobbling you up and down the side of hill (and therefore creating "extra" climbing).
Yeah I admit I haven't set up the waypoints so I might be best suited doing that.
I couldn't agree more, in theory the barometric altimeter should be the most accurate option, when mine was running properly with 3 or 4 people on the same ride we would be within less than a few vertical metres of one another which is super accurate i.e. less than 1% margin of error... - just need to work out why mine has now decided to go off the charts inaccurate…
Maybe try this. Find out the altitude of the start of Greenhill Rd climb (on the roundabout at Glynburn) and set this as a waypoint on your Garmin. Start your Garmin here and drive to the top of Mt lofty (where you know the altitude) - have the windows of your car open so the air pressure equalises a bit faster and put the Garmin on your dashboard so it gets a good view of the sky. From Glynburn to Lofty summit there is very little downhill so the Garmin altitude gain should be pretty close to Lofty summit minus Glynburn Rd roundabout.
Next, ride up the same route. Compare the two.
Next, ride back down. Compare altitude lost to the gain from the car and bike.
If air movement around the Garmin barometric altimeter hole is having an effect then the car altitude should be spot on, the bike ride might differ a bit and the bike ride down should be a lot different (though I cant work out if it will be more or less)
I’m just wondering if the new position sitting out at the front of the bike (the altimeter pick up holes now exposed to direct wind) could lift the pressure. The old position was out of the direct wind on the head stem where the wind didn’t directly hit the holes being protected by the head stem & mount.
I have also noticed the more extreme differences in vertical metres seems to occur on the flatter, faster rides where the average wind speed hitting the altimeter holes is higher. I’ll pop the old holder on the head stem, do a few rides and see if it has any affect and let anyone interested know the results.
Is there elevation correction on Strava? I thought it was only on Garmin Connect?
Yep, when you look at your ride, under the Elevation gained there is a field "Elevation (?)" that you can click on and select the correction there