Author Topic: Tricking strava into believing etrex elevation data  (Read 3457 times)

Tricking strava into believing etrex elevation data
« on: November 17, 2014, 06:56:34 pm »
I read somewhere that strava only trusts elevation data from certain devices (ie the bike specific ones) and there's no plan to support "trail" gps, ie etrex. Certainly, I get between 1/3rd and 1/2 of the elevation chopped from rides I do with mates with Edge series devices.

Opening a gpx file from my Etrex, I see that in includes a line

xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v1" creator="eTrex 30" version="1.1"

Is it as simple as changing it to what an Edge would say? What would an edge say?

Ta

Pingu

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Re: Tricking strava into believing etrex elevation data
« Reply #1 on: November 17, 2014, 10:21:23 pm »
Or fuck Strava and go to RideWithGPS which is very happily supporting my Etrex 30 GPX files.

fuaran

  • rothair gasta
Re: Tricking strava into believing etrex elevation data
« Reply #2 on: November 17, 2014, 10:39:38 pm »
The Edge models produce TCX or FIT files, so you would have to convert your GPX file to one of those. Probably easiest to use TCX format, as you can edit it in your text editor. This TCX Converter may help: http://www.tcxconverter.com/TCX_Converter/TCX_Converter_ENG.html
I'm not sure what you would have to do to make it look like a file from an Edge, I think TCX has an equivalent "creator" tag?

Or fuck Strava and go to RideWithGPS which is very happily supporting my Etrex 30 GPX files.
But does it actually use the elevation data from the Etrex? Or does it use its own elevation model (which may or may not be more accurate)?

For getting a bigger elevation score on Strava, probably the most useful thing is to set the GPS to record 1 point per second.

Re: Tricking strava into believing etrex elevation data
« Reply #3 on: November 18, 2014, 08:27:21 pm »
Or use an I phone

Dibdib

  • Fat'n'slow
Re: Tricking strava into believing etrex elevation data
« Reply #4 on: November 18, 2014, 09:45:06 pm »
Or use an I phone

Even if Strava used the built-in elevation from an iphone rather than their own computer model, why would that be any more accurate than a dedicated GPS receiver?

Kim

  • An appetite for the epic, but no real stamina
Re: Tricking strava into believing etrex elevation data
« Reply #5 on: November 18, 2014, 11:12:50 pm »
Quite the opposite, I'd have thought.  Anyway, the OP presumably has a perfectly good eTrex, so using an iPhone to log tracks is a bit arsebackwards.
Watching the TV without subtitles is like riding up a hill without using the gears :)

fuaran

  • rothair gasta
Re: Tricking strava into believing etrex elevation data
« Reply #6 on: November 18, 2014, 11:28:42 pm »
Depends on whether you want accuracy, or just big impressive numbers...

Re: Tricking strava into believing etrex elevation data
« Reply #7 on: November 19, 2014, 07:40:15 am »
That's true all you need to do is look at the climbing challenge on Strava all or most of the big hitters use an I phone or Android.
Perhaps that's why the AAA man has a low opinion of Strava, should just bin all the phone users that want to look good. I just look at the profile, lots of spikes shout I phone.it

Kim

  • An appetite for the epic, but no real stamina
Re: Tricking strava into believing etrex elevation data
« Reply #8 on: November 19, 2014, 12:12:57 pm »
Depends on whether you want accuracy, or just big impressive numbers...

Well if you're cheating why fuck about trying to collect noisy data.  It'd be simpler just to write a computer program to cook the elevation a bit.
Watching the TV without subtitles is like riding up a hill without using the gears :)

Re: Tricking strava into believing etrex elevation data
« Reply #9 on: November 19, 2014, 12:15:53 pm »
Depends on whether you want accuracy, or just big impressive numbers...

Well if you're cheating why fuck about trying to collect noisy data.  It'd be simpler just to write a computer program to cook the elevation a bit.

Digital EPO (google it)

Re: Tricking strava into believing etrex elevation data
« Reply #10 on: November 20, 2014, 11:10:03 am »
Depends on whether you want accuracy, or just big impressive numbers...

Just accuracy. My on screen numbers match my mates with Edge 500 and Edge 510.

As a test, I compared auto recording with 1sec and on screen. On my commute, I get ~530m on auto, 560 on 1sec and 600m on screen. However, on the recent Eureka 200, my mate got 1400m on his 510 on strava, whereas I got 800m. I don't recall what it said on screen.

According to some reports, it's simply down to Strava treating different models differently. I'm interested to see what Strava would do if I could trick it into thinking I was using an Edge.

Not interested in cheating, just knowing what I'm doing. I don't want to swap from Strava as loads of my mates are on there, as well as people from my cycling club.

Pingu

  • Put away those fiery biscuits!
  • Mrs Pingu's domestique
    • the Igloo
Re: Tricking strava into believing etrex elevation data
« Reply #11 on: November 20, 2014, 07:30:47 pm »
Or fuck Strava and go to RideWithGPS which is very happily supporting my Etrex 30 GPX files.
But does it actually use the elevation data from the Etrex? Or does it use its own elevation model (which may or may not be more accurate)?

Judging by the elevation profiles in the segments views, I'm guessing it uses data from the Etrex.

frankly frankie

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Re: Tricking strava into believing etrex elevation data
« Reply #12 on: November 21, 2014, 11:57:21 am »
As a test, I compared auto recording with 1sec and on screen. On my commute, I get ~530m on auto, 560 on 1sec and 600m on screen. However, on the recent Eureka 200, my mate got 1400m on his 510 on strava, whereas I got 800m. I don't recall what it said on screen.

Those sorts of discrepancies are easily accountable-for by different switch-on habits at the start of your ride.  Switching on and setting off all in one fluid movement (as many do) will often give rather different results to switching on, faffing with your kit for 5 minutes, resetting the trip counter and setting off (as many others do).
"This is a complex subject, with a need for more than one highlighter pen."

Euan Uzami

Re: Tricking strava into believing etrex elevation data
« Reply #13 on: November 21, 2014, 01:33:33 pm »
Depends on whether you want accuracy, or just big impressive numbers...

Well if you're cheating why fuck about trying to collect noisy data.  It'd be simpler just to write a computer program to cook the elevation a bit. not to bother
ftfy ;)

Re: Tricking strava into believing etrex elevation data
« Reply #14 on: November 21, 2014, 10:00:30 pm »
 :'( I like numbers.

I'm going to go count things.

Re: Tricking strava into believing etrex elevation data
« Reply #15 on: November 21, 2014, 10:36:27 pm »
Sadly, you are (re)discovering one of the fundamental truths of life. Whatever GPS device/app you're using - it never quite does what you want it do to; even though all your mates are using it.

One day - it'll get sorted. Maybe.

Re: Tricking strava into believing etrex elevation data
« Reply #16 on: November 22, 2014, 07:24:02 am »
...one of the fundamental truths of life. Whatever GPS device/app you're using - it never quite does what you want it do to; even though all your mates are using it.

 ;D

Re: Tricking strava into believing etrex elevation data
« Reply #17 on: November 23, 2014, 01:49:58 pm »
Sadly, you are (re)discovering one of the fundamental truths of life. Whatever GPS device/app you're using - it never quite does what you want it do to; even though all your mates are using it.

One day - it'll get sorted. Maybe.

It never quite does what it is expected to do with the configuration you have set. ??

Either, the device is junk, or the operator has overlooked an error in the configuration.

Usually, the latter.

Charlie Boy

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Re: Tricking strava into believing etrex elevation data
« Reply #18 on: February 01, 2015, 04:36:16 pm »
I've never bothered to check the difference in altitude gained until today. I have Strava on my phone in my back pocket and a Garmin Dakota on the bars for a route and as a computer (this has a barometric altimeter so should be fairly accurate you would think). The Garmin gave me 912m this morning, Strava gave me 770m. Bikeroutetoaster, on which I planned the route and uploaded it to my Garmin, gives it 660m.

So I guess the Strava iphone app is the average.
Mojo is being awakened.

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Re: Tricking strava into believing etrex elevation data
« Reply #19 on: February 03, 2015, 10:08:48 pm »
With a bit of mucking about Strava can use the data from a GPS with barometric altimeter, even if it is not one of their listed devices, which are the Edge Series.

Their API for developers explains that if the creator tag is changed it will use the elevation data from the GPS. So, to quote the relevant bit from their page:

A generic “with barometer” device is provided to force the system to use the elevation data from TCX and GPX file types. One only needs to add “with barometer” to the end of the creator name. For example, a TCX file would include something like:
 <Creator> <Name>My Awesome App with barometer</Name> </Creator>
and a GPX file should have an updated creator like:
<gpx version="1.1" creator="Best app ever with Barometer">.


Use a text editor, open file, add "with barometer", save and upload as normal.

Kim

  • An appetite for the epic, but no real stamina
Re: Tricking strava into believing etrex elevation data
« Reply #20 on: February 03, 2015, 11:23:39 pm »
They do that, but they won't recognise an eTrex?  *boggle*
Watching the TV without subtitles is like riding up a hill without using the gears :)

JonB

  • Granny Ring ... Yes Please!
Re: Tricking strava into believing etrex elevation data
« Reply #21 on: February 04, 2015, 04:58:07 pm »
With a bit of mucking about Strava can use the data from a GPS with barometric altimeter, even if it is not one of their listed devices, which are the Edge Series.

Their API for developers explains that if the creator tag is changed it will use the elevation data from the GPS. So, to quote the relevant bit from their page:

A generic “with barometer” device is provided to force the system to use the elevation data from TCX and GPX file types. One only needs to add “with barometer” to the end of the creator name. For example, a TCX file would include something like:
 <Creator> <Name>My Awesome App with barometer</Name> </Creator>
and a GPX file should have an updated creator like:
<gpx version="1.1" creator="Best app ever with Barometer">.
Use a text editor, open file, add "with barometer", save and upload as normal.

Wow, that worked  :thumbsup: thanks tubby. Saturday's ride went from 3000M to 4600M, I probably won't bother for all rides but it's nice to know the possibility is there.  As Kim points out, if it's this simple to do in a text file, you can't imagine it would be much of a problem for Strava to sort it out for the Etrex cycling community.  The variation in climbing figures is a bit absurd on Strava between those with altimeters and those without but there are significant variations within these groups as well, it makes their climbing challenges a bit of a joke!

Kim

  • An appetite for the epic, but no real stamina
Re: Tricking strava into believing etrex elevation data
« Reply #22 on: February 04, 2015, 06:26:32 pm »
As Kim points out, if it's this simple to do in a text file, you can't imagine it would be much of a problem for Strava to sort it out for the Etrex cycling community.

I think it's political, like they way they only understand the concepts of "Road bike" "Mountain bike" "TT bike" and "cross bike".  Even if those pull in different models for calculating power/calories and they only have four models, it seems restrictive to the point of ridiculousness.  (None of the bikes I ride regularly fit those categories in a meaningful way.)
Watching the TV without subtitles is like riding up a hill without using the gears :)

Re: Tricking strava into believing etrex elevation data
« Reply #23 on: February 04, 2015, 07:35:11 pm »
As Kim points out, if it's this simple to do in a text file, you can't imagine it would be much of a problem for Strava to sort it out for the Etrex cycling community.

Strava's development seems to be rooted in 'racing' - so their preferred devices are those that support FIT files, which can contain HR, power, cadence and lap data as standard. These same extensions to GPX files are not necessarily part of the core schema and can look different, depending on device. I suspect that for Strava, there is no return on investment to support a wider range of devices. Those who pay for the premium metrics will probably own the Edge series anyway. It could be argued it would be trivial for Garmin or any other manufacturer to modify their "creator" tags in a firmware update to add "with barometer" to their device description.

JamesBradbury

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Re: Tricking strava into believing etrex elevation data
« Reply #24 on: April 29, 2015, 06:37:35 am »
Excellent, thanks.  :thumbsup:

For the record, I changed the creator attribute within the first "gpx" tag as follows:-

Code: [Select]
creator="eTrex 30 with Barometer"