Elevation issues on Garmin?

[livpoksoc]

I went out for a ride this morning (mapped on Strava, loaded via phone on Garmin Connect sync). Got a few miles out and thought best check the expected elevation to manage myself, and it said 1900 metres. Thought that felt a bit high, but anyway got pedalling. Took a stop at halfway point as I'd only covered 25% of the elevation - I know my route covered a decent climb at the end, but not 3x what I'd already covered. I opened Strava app and checked the elevation there - 583 metres. Great for me, but just wondering how or why it can be so disparate?

I noticed when I was on the elevation screen that there were lots of little spikes, rather than a smooth gradient like I was experiencing on the road, but not sure how Garmin can have those in it's maps?

Footnote my actual elevation ended up being 510m with no deviation from the route, so Strava wasn't spot on either.

 

[livpoksoc]

Forgot to post this as a question, so cheeky bump...anyone else encountered this at all?

 

[livpoksoc]

Just to clarify, what you're talking about is the estimated elevation for a route (or course or whatever Garmin call them). Not the actual measured elevation of a ride (or track or activity). Is that right?

So pressure variations, not resetting the altimeter and so forth would be irrelevant here. It's the Garmin figuring out how much elevation is in the route. Not the Garmin measuring elevation as you ride.

Here's my guess: The unit doesn't compare the route to inbuilt map data to figure out the elevation profile. Rather the route itself contains the altitude info: It's a series of points with latitute, longitude and altitude. (At least, that's true of tcx files). The Garmin just walks along the info in the route to plot the elevation profile, just as it walks along the lat/long co-ords to plot the map. Therefore my guess is that whatever wonkiness existed, was in the route that you downloaded, and originated in the mapping data that was used when the route was plotted. So by my guesswork I'd point the finger at Strava having concocted a route file with wonky altitude data.

All a guess. Could be wrong.

Potentially - however the route I plotted on Strava lists the elevation as 1,916ft (583m) and was much more accurate to real life than Garmin's interpretation of the route which was out by over 100%.

What is odd is I just logged into Connect and Garmin's own courses section has the route there with the same 1,916ft elevation and the profile doesn't look anywhere near as up and down as the version my Edge 520 displayed...so it's either something happening with the route being uploaded to the device wirelessly causing the haywire, or that the Edge 520 has some cuckoo elevation profile of one or two of the roads I went on?

 

[livpoksoc]

I think it's a one off, but then I also did have to do some maths a few weeks ago but it was displaying elevation in the summary lage in ft, but on the ride screen in metres.

Will keep an eye out anyway.