my strava rides aren't calculating elevation properly?- Mtbr.com
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  1. #1
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    my strava rides aren't calculating elevation properly?

    went on a ride this afternoon with my wife she also tracked the ride on strava and she recorded 1200+ vertical on 7~mile ride..

    where my phone recorded 400~ on the same ride??

    anyone have any ideas what is wrong?



    her tracking of the elevation gain is much more likely to be accurate as we rode up into this mountain thing

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  2. #2
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    I don't know what your's is doing, but every now and then my Garmin 520 decides to do weird stuff that can't be explained or easily corrected. As a last resort, I have saved all of my data and performed a reset and reload my files and things magically return to normal.

    If you have any questions, give Garmin support a call.
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  3. #3
    Meatbomb
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    Grow a pair and do worry about STRAVA.... No one really cares how fast you can ride but you...

  4. #4
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    Quote Originally Posted by Phillbo View Post
    Grow a pair and do worry about STRAVA.... No one really cares how fast you can ride but you...
    lol.. fair enough.. I honestly don't care that much in general but I've just turned 50 and I've been trying to get in better shape and being able to semi~ accurately track climbing ..etc would be helpful.. it isn't about being a strava bro at all.. my PR's are all pretty consistently 60% percentile at best.. I'm just trying to see how my getting in better shape is going.

  5. #5
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    Quote Originally Posted by Cleared2land View Post
    I don't know what your's is doing, but every now and then my Garmin 520 decides to do weird stuff that can't be explained or easily corrected. As a last resort, I have saved all of my data and performed a reset and reload my files and things magically return to normal.

    If you have any questions, give Garmin support a call.
    k thanx.. in my case I was recording with a Galaxy smartphone my wife has a garmin (model I'm not sure what).. maybe I'll reinstall the app on my phone ..or start using my bike computer thing again instead?

    thanx for the reply.

  6. #6
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    If Strava has not recorded those ride properly, you're simply going to have to do them over. That is the rule, you know.
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  7. #7
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    Quote Originally Posted by atarione View Post
    I was recording with a Galaxy smartphone .
    There ya go, that's the problem, and why a lot of us use a GPS garmin, and even then you can still have issues. so far my 520 plus has been stellar. Not only that but I love when I wreck it ask me if im ok

  8. #8
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    +1 on the Garmin 520. It uploads right to Strava.
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  9. #9
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    Quote Originally Posted by atarione View Post
    k thanx.. in my case I was recording with a Galaxy smartphone my wife has a garmin (model I'm not sure what).. maybe I'll reinstall the app on my phone ..or start using my bike computer thing again instead?

    thanx for the reply.
    Your wife's Garmin probably has a barometric altimeter, your phone does not.

    https://support.strava.com/hc/en-us/...bile_site=true

  10. #10
    EAT MORE GRIME
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    if you process your gpx or fit file against a real mapping program you will get accurate altitude (like running a garmin trace thru garmin web site that will fix altitude for you)

    if you rely on your device only, it will be inaccurate a lot of times unless it is using more precise calculations (5+ sats...8 can be seen at any one time) and not using barometric pressure. most gps uses air pressure to estimate altitude and tracks you on 3-4 sats at a time, and you get dropouts with trees and valleys and the weather


    so, it will vary all the time unless you go advanced, sync with 5 sats+ or have one that combines multiple constellations are once such as navstar+glonass

    technically all that is needed is 4 sats to precisely locate you in 3 dimensional space, but you can almost never get zero dropouts unless at sea on a clear night
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  11. #11
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    Go to Strava using a web browser and bring up your ride. In the top right there is button that says "correct elevation". Click on it and then refresh your browser page. See if that corrects the elevation.

  12. #12
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    Due to inherent differences between how elevation is measured between your phone and a Garmin, this is to be expected. Phones are fine for super casual use, but if you want better accuracy or more fitness measurements, they just don't cut it.

    Quote Originally Posted by mrallen View Post
    Go to Strava using a web browser and bring up your ride. In the top right there is button that says "correct elevation". Click on it and then refresh your browser page. See if that corrects the elevation.
    This is about the best you can expect, but there will still be discrepancies. What Strava does here is scrap any elevation data in the original file (or ignore it) and compare the positional data of your track to an elevation database. That elevation database assigns a 3mx3m square on the map with the same elevation. Elevation changes that occur within that area won't be captured, so it's likely that the resulting track will show less total climbing than actually occurred, and the elevation profile will look significantly smoother than the one from the Garmin (with the barometric altimeter).

    The Garmin with the barometric altimeter also isn't showing the actual elevation. There are errors inherent with that measurement method, too. Barometric drift being the major one (changes in air pressure tricking the computer into showing more elevation change than actual). A low pressure system moving in would make the GPS show you're climbing more than you are, or descending less. A high pressure system moving in might make the GPS show you climbing less than you are, or might show you descending more. The way you get around this with a barometric altimeter is frequent calibration to known elevation (such as USGS benchmarks, known summit elevations, other known elevation locations). Garmin started giving Edge computers the ability to calibrate the elevation awhile back, IIRC. Some models give more options such as auto calibrations.

    https://support.garmin.com/en-US/?fa...mV6Atph276U4h8

    https://support.garmin.com/en-US/?fa...nZ99DcunfAue66

    Manual calibrations to USGS benchmarks are by far the most accurate for spot elevations. But cutting out the effects of barometric drift requires some frequency with calibrations.

    Consequently, elevation change simply doesn't rank as something as a really high priority for me to "get accurate" because it's just not practical to do so on a bike computer. It's not like you're able to measure it directly the way you can with wheel circumference and a wheel sensor, or a cadence sensor, HRM, or power meter. My riding buddies and I joke all the time about the discrepancies between our different devices on the same ride. Elevation change is the "fish story" of our mtb rides. We use the elevation from the device that reported the most change when telling stories amongst our group, accurate or not.

  13. #13
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    I never trust elevation on anything besides a real GPS device. I did a 200 mile sail from San Diego. I tracked it on my phone. Said I climbed 3k ft. I'm on a sailboat at sea level. My boat's advanced GPS said it changed 7ft with the tide.

  14. #14
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    Quote Originally Posted by Harold View Post
    Elevation changes that occur within that area won't be captured, so it's likely that the resulting track will show less total climbing than actually occurred, and the elevation profile will look significantly smoother than the one from the Garmin (with the barometric altimeter).
    I find this to be the exact opposite of what happens in my area. We have a lot of short up and down sections of trail that the Garmin, just doesn't capture well. I think you just go through them fast enough that it doesn't register well. On these trails, the elevation difference can be up to 40% lower on the Garmin than something that uses map matching like Strava. The difference is much less on trails where the climbs are longer. And yes, sometimes it will show more elevation gain on the Garmin, but rarely.

    I do agree that elevation are fairly unimportant, regardless of the accuracy.

  15. #15
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    Quote Originally Posted by mrallen View Post
    a lot of short up and down sections of trail that the Garmin, just doesn't capture well.
    My experience with the Garmin 520 as well.
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  16. #16
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    good information thank guys .. I hadn't realized how poor the mobile app was at keeping track of elevation..

    on the upside I climb a lot better than I thought I did based on the strava numbers =p

    for various reasons... mainly I got it for free I have this GPS bike computer thing that I'm going to try today and see how it compares to the phone.

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  17. #17
    since 4/10/2009
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    Quote Originally Posted by mrallen View Post
    I find this to be the exact opposite of what happens in my area. We have a lot of short up and down sections of trail that the Garmin, just doesn't capture well. I think you just go through them fast enough that it doesn't register well. On these trails, the elevation difference can be up to 40% lower on the Garmin than something that uses map matching like Strava. The difference is much less on trails where the climbs are longer. And yes, sometimes it will show more elevation gain on the Garmin, but rarely.

    I do agree that elevation are fairly unimportant, regardless of the accuracy.
    Depends in part on your settings. If you're using "Smart" recording on your Garmin, you're setting yourself up for failure, because elevation is only being recorded at whatever interval GPS points are being recorded, which could very easily miss small elevation changes. The best you can do is record at 1sec intervals. At that frequency, your little elevation changes would have to be awful tiny to be missed.

    If you're matching elevation to a DEM (digital elevation model) with 3m pixel sizes (the standard best), think about that for a second...that's a ~9ft square. Quite a bit can happen in that amount of space. With a 1sec recording interval, you can reasonably get multiple points recorded in that kind of space, especially if you're talking small rollers. Whereas the DEM would be lucky to capture part of the elevation change.

    You also have to consider the vertical accuracy of your measuring device. The second Garmin article points out that the expected accuracy of a CALIBRATED barometric altimeter is about +/-10ft per recorded point (my Edge 520 is definitely not a well calibrated device). If your elevation changes are less than that, the barometric altimeter may not capture them at all. GPS-derived elevation accuracy is dependent on (but lower than) the positional accuracy, so it will vary over time depending on the quality of the reception your device has from satellites. The accuracy of matching the activity to an elevation database depends on the positional accuracy of your GPS track, the relief of the terrain you're riding (the steeper it is, the greater the matched elevation readings will differ when your track deviates from the path you actually rode), AND the accuracy of the elevation database itself.

    Once you get there, THEN you have to consider...how do we know what the actual elevation change of a given ride is? Frankly, we have no way of knowing what the actual is. Every individual elevation measurement is based on some oversimplified model of the shape of the earth. The earth's shape is not perfect, and the various models account for more or less of that imperfection. None account for all of it. Sea level is not the same across the planet, either (0 elevation) because of tides and uneven distribution of water in the oceans.

    With the big picture issues with elevation change measurement on mountain bike trails, it's simply pointless to quibble about whether your chosen device is able to capture the elevation change from a bunch of 2 or 3ft rollers.

  18. #18
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    I'm just happy with consistency.
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  19. #19
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    Vertical gain on my 520 is always a few if not several hundred feet less than what Strava shows. I have two 520s, same for both.
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  20. #20
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    Is your STRAVA and your 520 mutually exclusive?

    My 520 is the data provider for STRAVA.
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  21. #21
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    They are if they are not linked and I run both separately for comparison purposes.
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  22. #22
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    Quote Originally Posted by Phillbo View Post
    Grow a pair and do worry about STRAVA.... No one really cares how fast you can ride but you...
    This post is uncalled for. Please do not make personal attacks on people asking honest questions.




    To the OP:
    I am having a issue with the GPS on my phone of late as well. My last three rides show me shooting off the trail in a direct line and then back again. This adds mileage I did not do, and I don't like that. i want my recordings to be accurate on my distance traveled.

    I contacted Strava Support and this was thier reply, I have done the GPS reset thing and plan to test my strava tomorrow.

    Hello Matthew,

    According to your ticket it appears you may be having problems recording activities from our Android mobile app.

    Important Note - there was recently an update to how GPS records time, and your device could be experiencing problems as a result of that change. Please see our article on Activity Syncing Issues and Incorrect Start Times to see how this change may have affected you and what you can do to prevent problems in the future.

    In most other cases these types of issues can be resolved with some basic GPS troubleshooting

    First of all, please simply try turning your phone completely off then on and flipping location services off then back on. If you continue to have problems, please check your system settings and disable any battery saver apps you have before you record.

    If you continue to have problems please try doing an "AGPS reset", which will sometimes help with GPS connection/signal problems.

    AGPS Reset
    • Install the app ["GPS Status & Toolbox"](http://tinyurl.com/7xfpfko) from the Play Store.
    • Then in that app, select Menu > Tools > Manage A-GPS State > Reset.
    • Select Menu > Tools > Manage A-GPS State > Download.



    For more information, see our article on troubleshooting GPS issues.

    If you're still having problems, please reply to this ticket with any additional information or this ticket will close automatically after 3 days.
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  23. #23
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    thanx Klurejr and everyone for the information I will try the steps strava listed.

  24. #24
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    I get a kick out of looking at the elevation changes after a ride, sometime starting and stopping at the same spot and there is a 200 or more foot elevation difference in the beginning and final elevations. If I lost a lot of elevation it always seems to rain later.

  25. #25
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    Quote Originally Posted by Tribble Me View Post
    I get a kick out of looking at the elevation changes after a ride, sometime starting and stopping at the same spot and there is a 200 or more foot elevation difference in the beginning and final elevations. If I lost a lot of elevation it always seems to rain later.
    The real fun ones for me are when I stop somewhere along the ride to hang out for at least half an hour. Somewhere with a good view, or a spot where I need to eat some food and recharge, whatever. Then when looking later on at the graph of elevation by distance, I see a jump in the elevation (up or down, depending on the weather system moving in). If you look at the chart over time, that jump gets smoothed out by the gradual change, but if you can find the time where you were no longer moving, you can often hover your cursor over the graph and see that the elevation is slowly changing, yet your location on the map is not changing.

    It really does make the "atmospheric drift" concept stand out when you can compare those two elevation plots and see how they differ. In addition to differences in starting and finishing elevations, assuming your ride starts and ends in the same place.

  26. #26
    The White Jeff W
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    Quote Originally Posted by Phillbo View Post
    Grow a pair and do worry about STRAVA.... No one really cares how fast you can ride but you...
    ...and the award for most predictable comment goes to...

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