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STRAVA incorrectly calculating total elevation/altitude

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Recent issue with Strava.

Meaning … DON’T BELIEVE THE ALTITUDE DATA IN STRAVA.

I did a local course this morning. The Magellan Cyclo 505 stated 4,080.56 feet of climbing. When I uploaded this ride to Strava, Strava said 6,918 feet. How can these be so different?

The Magellan Cyclo GPS creates a GPX file and every second builds on this file as you ride, updating each parameter including Lat, Lon, elev, hr, power, etc.

After the ride, when you hit STOP, the cyclo ends the recording, calculates the totals and closes the file – that’s why it takes several seconds for the Cyclo 505 to respond after you hit STOP.

At home, you can upload this file to your local Magellan account where a graphical representation of the ride is displayed.

Regarding Altitude, the Magellan adds all of the waypoints up and, for this ride was calculated to be 4,080.56 feet. I then uploaded to Strava and now the total Ascent is 6,918 feet. So where is the discrepancy?

I then took the GPX file and changed each <ele> to <xxx> and </ele> to </xxx>. What this does is to zero out the Altitude/Elevation because the file now contains no elevation (which is represented by the <ele> tag). Re-uploading this ride to Strava I would expect to see ‘0’ Elevation, but instead, I still see 6,918 feet.

What this shows is that Strava is NOT looking at the GPX file for elevation but instead doing some kind of internal algorithm which is actually INCORRECT.

Following is an abbreviated GPX file showing several Track Segments – <trkseg> where each <ele> has been changed to <xxx> and each </ele> changed to </xxx>. This zeros out the elevation so uploading should show 0 for elevation.

<?xml version=”1.0″ encoding=”UTF-8″ standalone=”no”?>
<gpx xmlns=”http://www.topografix.com/GPX/1/1″ version=”1.1″ creator=”Magellan Cyclo ver. 4.1 – http://www.magellangps.com/”>
<metadata>
<time>2014-12-11T01:13:32Z</time>
</metadata>
<trk>
<name>Laguna Niguel 1</name>
<type>speed</type>
<desc></desc>
<cmt></cmt>
<extensions>
<fileid>dev_00022AC1FC92010010000000004A97F7_A34511A6-A714-BE1E-ACF2-3078C7A78A2B</fileid>
<profile>Rick Road1</profile>
<time>2014-12-10T17:13:32Z</time>
<length>58151.068718</length>
<timelength>9113</timelength>
<minlat>33.462051</minlat>
<minlon>-117.730438</minlon>
<maxlat>33.542850</maxlat>
<maxlon>-117.681595</maxlon>
<avgspeed>6.381111</avgspeed>
<maxspeed>20.567490</maxspeed>
<minacceleration>-1.661655</minacceleration>
<maxacceleration>1.713100</maxacceleration>
<minaltitude>34.183891</minaltitude>
<maxaltitude>303.751556</maxaltitude>
<totalascent>1243.753559</totalascent>
<totaldescent>1233.808102</totaldescent>
<calories>1982.950433</calories>
<avggrade>4.175912</avggrade>
<chainring>34 50</chainring>
<cassettetype>28 25 23 21 19 17 16 15 14 13 12</cassettetype>
<cassettemodel>11</cassettemodel>
</extensions>
<trkseg>
<trkpt lat=”33.462646″ lon=”-117.707024″>
<xxx>34.903248</xxx>
<time>2014-12-10T17:13:32Z</time>
<extensions>
<distance>0.000000</distance>
<speed>0.766522</speed>
<course>0.874910</course>
<acceleration>0.185200</acceleration>
<cadence>0</cadence>
<heartrate>0</heartrate>
<power>0</power>
<frontgear>0 0</frontgear>
<reargear>0 0</reargear>
</extensions>
</trkpt>
</trkseg>

<trkseg>
<trkpt lat=”33.462643″ lon=”-117.707001″>
<xxx>34.807800</xxx>
<time>2014-12-10T17:13:49Z</time>
<extensions>
<distance>0.000000</distance>
<speed>0.823111</speed>
<course>0.874910</course>
<acceleration>-0.308667</acceleration>
<cadence>0</cadence>
<heartrate>0</heartrate>
<power>0</power>
<frontgear>0 0</frontgear>
<reargear>0 0</reargear>
</extensions>
</trkpt>


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