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Strava - elevation discrepancy

Just got back from a ride out of London into Surrey and notice the elevation listed for the ride on Strava is way lower than I was expecting.

When I planned the route in Strava's Route Builder, it was listed as 55.6 miles and 3,651 ft elevation. When I uploaded the activity, it says I did 56.4 miles and 2,528 ft elevation, despite following the route exactly.

That's obviously a pretty huge discrepancy between the route planner and the actual ride - over 1,000 ft elevation. Does anyone know why that is?

Thanks.

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22 comments

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nellybuck@msn.com | 8 years ago
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This was quite an interesting look at Strava and elevation, which may shed some light;
http://regex.info/blog/2015-05-09/2568

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alijfowler | 8 years ago
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You might find that if you are using 'smart data recording' on the Garmin then it isn't constantly reassessing your elevation whereas '1 second' recording will and may provide more accurate elevation readings.

As the barometric altimeter measures elevation by changes in air pressure, if you are riding on a day that has changeable weather conditions then your elevation data may not be accurate.

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sergius replied to alijfowler | 8 years ago
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alijfowler wrote:

As the barometric altimeter measures elevation by changes in air pressure, if you are riding on a day that has changeable weather conditions then your elevation data may not be accurate.

I've been wondering about that - I don't really understand how barometric can be more accurate than calculations from 7+ glonass satelites.

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kwi | 8 years ago
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I'll second that, topped an 800ft in a blizzard, quick look at the Garmin....7ft, I nearly cried.

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arfa | 8 years ago
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There is a well known glitch with garmins that they become highly inaccurate when it rains if water gets near the barometric sensor. You can fix this with auto correct.
As for barhatch and whitedown, there's little between them in nastiness. Both are a smidge over 300 ft, but whitedown edges ithe for me with a steeper gradient at its worst. Neither though are a patch on Rosedale chimney where I genuinely thought if I lost forward momentum I would be in serious danger of falling back down the hill !

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andyp | 8 years ago
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You know they're not important awards, right? Dave Brailsford isn't going to be on the phone whether you meet a nominal Strava target or not...

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dave atkinson replied to andyp | 8 years ago
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andyp wrote:

You know they're not important awards, right? Dave Brailsford isn't going to be on the phone whether you meet a nominal Strava target or not...

what, you've never set yourself a personal challenge?

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livestrongnick | 8 years ago
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Thanks to the correct elevation i missed out on the April climbing challenge badge by 10m  14
Would've been my 1st ever badge  20

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Al__S | 8 years ago
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My Garmin (Edge 510) often goes a little bit crazy on elevation (any advice on fixing this), sometimes making it look as if I've ridden off a 100m cliff in the middle of the fens. I tend to hit "correct elevation" in Strava (web only, sadly not in the app) to get a better idea, that uses the topographic information from the maps.

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sergius | 8 years ago
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Sure thing, starting from Sutton so the first/last 15 miles are getting to the general vicinity:

https://www.strava.com/activities/287598276

Looking at Barhatch, I've not been down there - looks like it could be tacked onto my loop pretty easily though between Hound House and Ewhurst.

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ashfanman replied to sergius | 8 years ago
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sergius wrote:

Looking at Barhatch, I've not been down there - looks like it could be tacked onto my loop pretty easily though between Hound House and Ewhurst.

Tacked on pretty easily, if not ridden pretty easily...  3

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ianrobo | 8 years ago
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Strava is more accurate like with Garmin connect than the 810 or whatever. I have checked on garmin forums etc and no one doubts that. You need to make sure you upload via garmin and then apply elevation correction, remembering it synchs with strava anyway.

However I keep the higher value as it looks better !

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ianrobo | 8 years ago
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Afraid it is the Garmin which is wrong. No getting away from that, it works it out incorrectly and in Garmin Connect the elevation correction always knocks off 20% or so from what the Garmin says.

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sergius | 8 years ago
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Crocknorth sucks. But it's not quite as bad as White Down Lane.  1

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ashfanman replied to sergius | 8 years ago
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sergius wrote:

Crocknorth sucks. But it's not quite as bad as White Down Lane.  1

I've done White Down before - a Paris-to-London I did last summer came back that way. Steep indeed. But I actually think I found Crocknorth worse as I wasn't expecting it to be that steep - particularly given that the first section wasn't bad at all. It got my attention after I went round the corner to the left though!

I've planned another route that goes up both Crocknorth and White Down, but I might build up to that!

ianrobo wrote:

Afraid it is the Garmin which is wrong. No getting away from that, it works it out incorrectly and in Garmin Connect the elevation correction always knocks off 20% or so from what the Garmin says.

So the elevation on the Strava route planner is accurate (or at least more accurate)? Or are they both completely unreliable?

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sergius replied to ashfanman | 8 years ago
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ashfanman wrote:
sergius wrote:

Crocknorth sucks. But it's not quite as bad as White Down Lane.  1

I've done White Down before - a Paris-to-London I did last summer came back that way. Steep indeed. But I actually think I found Crocknorth worse as I wasn't expecting it to be that steep - particularly given that the first section wasn't bad at all. It got my attention after I went round the corner to the left though!

I've planned another route that goes up both Crocknorth and White Down, but I might build up to that!

ianrobo wrote:

Afraid it is the Garmin which is wrong. No getting away from that, it works it out incorrectly and in Garmin Connect the elevation correction always knocks off 20% or so from what the Garmin says.

So the elevation on the Strava route planner is accurate (or at least more accurate)? Or are they both completely unreliable?

My local 75 mile training loop does Ranmore > Green Dene > Hound House > Leith Hill > Newlands Corner > Crooknorth > Box Hill. The thought of adding White Down to that makes me shudder  1

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ashfanman replied to sergius | 8 years ago
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sergius wrote:

My local 75 mile training loop does Ranmore > Green Dene > Hound House > Leith Hill > Newlands Corner > Crooknorth > Box Hill. The thought of adding White Down to that makes me shudder  1

Sounds like a nice loop. Do you have a link to the route on Strava (or somewhere else I could get a GPX)?

I like having Box Hill at the end of rides as it's a nice, gradual effort, so good with tired legs. Having White Down at the end would be brutal.

Have you been up Barhatch/Winterfold? I hear that one's nasty. Harder that White Down?

My club has been talking about doing that ride that takes in all the main climbs of the Surrey Hills: Leith, Box, Crocknorth, White Down, Barhatch, etc. Forget what it's called, but not sure I could hack that just yet...

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ashfanman | 8 years ago
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I did lose signal a few times on the ride when I went through forested areas, but I can't see that accounting for such a huge difference.

I guess I should trust the (lower) elevation recorded on the ride by the Garmin, rather than the elevation from the route plan on Strava? Pity - I'd feel better about the dull ache in my legs if I had actually climbed the lost 1,000ft! Crocknorth was a lot steeper than I was expecting... Good ride either way!

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Simon E | 8 years ago
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I'd not trust Strava for elevation data, I have seen significant discrepancies between people riding the same route, even in the same event.

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ashfanman | 8 years ago
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Recorded using a Garmin 1000.

I'd expect to see some discrepancy, but 3,650ft to 2,500ft is a pretty significant difference...

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AWP | 8 years ago
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Agree with sergius. It'll probably be down to the device you are using not having barometric assistance to calculate change in altitude. Relying on pure GPS in not going to be accurate.

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sergius | 8 years ago
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You haven't said whether you recorded using a phone (just GPS) or a Garmin or similar (with barometric altitude).

Assuming it's a phone, the GPS calculations are often flaky - before I got the Garmin I'd routinely see variations in distance of +/- 2 miles on the same 65 mile route, and elevation would vary by a few hundred feet - I believe spotty signal coverage is the generally accepted cause.

The Garmin is better - but you'll still see variations but over a much tighter range.

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