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  1. #1
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    Why does my Garmin 510 overstate elevation gains?

    I have the new sensor that wraps around the wheel hub and the crank arm. Elevation gains are overstated by least 400ft+....do I need to?recalibrate the sensors somehow or firmware?

  2. #2
    Bianchi-Campagnolo
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    Those sensors don't measure elevation, but wheel and crank arm revolutions for speed and cadence respectively.
    Elevation gain (and loss) is taken from GPS and/or GLONASS data which is aquired by the unit itself. A firmware update never did a Garmin unit any harm. Also it is a good thing to calibrate elevation to you usual starting position, because sometimes the data aquired is somewhat off.
    They do anything just to win a salami in ridiculous races. I take my gear out of the car and put my bike together. Tourists and locals are watching from sidewalk cafes. Non-racers. The emptiness of those lives shocks me. It was the illest of times, it was the dopest of times. And we looked damn good. Actually the autobus broke down somewhere on the Mortirolo.

  3. #3
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    Quote Originally Posted by kbwh View Post
    A firmware update never did a Garmin unit any harm.
    I beg to differ. I've experienced and know people who have experienced issues ranging from minor functionality to completely bricking the unit.

    When I was still a garmin owner, I learned to thoroughly read the release notes and only apply updates if they were resolving an issue I was experiencing, or adding a feature I wanted.

  4. #4
    Bianchi-Campagnolo
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    I'm not saying that any Garmin FW update has been flawless, or that it's particularly robust overall, quite the contrary actually. But I cannot say their FW has become worse with any update.
    They do anything just to win a salami in ridiculous races. I take my gear out of the car and put my bike together. Tourists and locals are watching from sidewalk cafes. Non-racers. The emptiness of those lives shocks me. It was the illest of times, it was the dopest of times. And we looked damn good. Actually the autobus broke down somewhere on the Mortirolo.

  5. #5
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    The explanation I always hear is that the GPS units take their elevation data from the existing map info, not from direct readings. So if you take a bridge across a 1000-foot-deep canyon, you get credit for doing 1000 feet down and then 1000 feet back up the other side. (Just as an extreme example.)

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    What map data are you comparing against? I find route builders on Strava.com and MapMyRide.com can have vastly different elevation gains for the same route.

  7. #7
    tlg
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    Quote Originally Posted by hchan View Post
    I have the new sensor that wraps around the wheel hub and the crank arm. Elevation gains are overstated by least 400ft+....do I need to?recalibrate the sensors somehow or firmware?
    How do you know it's off 400ft? What are you comparing to? And over what distance?
    There is no exact science to measuring elevation. Barometric sensors have quite a margin of error. As does GPS data. As does mapping data.
    Do the same ride with a dozen people using the same unit, and you'd be lucky to have them all within 400ft.

    Some good information here.
    Garmin 510 overstating elevation -natural limitation of barometer?

    Quote Originally Posted by kbwh View Post
    Elevation gain (and loss) is taken from GPS and/or GLONASS data which is aquired by the unit itself.
    Incorrect. The Edge 510 gets it's elevation from a barometric sensor.


    A firmware update never did a Garmin unit any harm.
    Ha. Tell that to my friend who just sent her bricked 1000 back to Garmin after an update. They can't even fix it, they're replacing it.
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  8. #8
    tlg
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    Quote Originally Posted by BlazingPedals View Post
    The explanation I always hear is that the GPS units take their elevation data from the existing map info, not from direct readings. So if you take a bridge across a 1000-foot-deep canyon, you get credit for doing 1000 feet down and then 1000 feet back up the other side. (Just as an extreme example.)
    That is one issue, but the other way around. When going across a bride, the garmin will measure elevation from barometric. Showing no change. But RWGPS which uses map data will show elevation change.

    Another which is a bigger issue is smoothing. There's always some variance in the data which get's smoothed. If it's off just a small percent, it can add up to a lot over a ride. What if there's a small hump in the road that changes your elevation 2ft. How do you count that? Is it a "hill". How the algorithms account for things like that can easily add up to hundreds of feet.
    Custom Di2 & Garmin/GoPro mounts 2013 SuperSix EVO Hi-MOD Team * 2004 Klein Aura V

  9. #9
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    i believe garmin bike computers use a barometric altimeter. what causes them to be off are weather related issues. its probably not firmware(at least that's what my 810 does). It also allows you to set starting location which improves accuracy.
    Last edited by Trek_5200; 05-08-2017 at 07:51 AM.

  10. #10
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    I thought my Garmin was giving me a few extra feet just to help me feel better about myself.

  11. #11
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    Quote Originally Posted by hchan View Post
    I have the new sensor that wraps around the wheel hub and the crank arm. Elevation gains are overstated by least 400ft+....do I need to?recalibrate the sensors somehow or firmware?
    400 feet compared to how many? 400 instead of zero? Or 10,400 instead of 10,000? If the latter, I would consider it fairly accurate as far as elevation gain goes with any unit.
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  12. #12
    I love to climb!
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    Quote Originally Posted by BlazingPedals View Post
    The explanation I always hear is that the GPS units take their elevation data from the existing map info, not from direct readings. So if you take a bridge across a 1000-foot-deep canyon, you get credit for doing 1000 feet down and then 1000 feet back up the other side. (Just as an extreme example.)
    Your hearing the wrong explanation. Most of the Garmin units use a barometric altimeter, so they'll never do what you're describing. Maybe some of the lower units that don't have barometric altimeter will do that.
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  13. #13
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    I agree that Garmins record too much elevation. I have an old Avocet 50 that records much less.

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    Quote Originally Posted by Trek_5200 View Post
    i believe garmin bike computers use a barometric altimeter. what causes them to be off are weather related issues. its probably not firmware(at least that's what my 810 does). It also allows you to set starting location which improves accuracy.
    A starting location won't change the gain/loss, it just "zeroes" the current value to a known number (that you preset), but altitude gain over a ride will still be the same regardless of what the starting value is.

  15. #15
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    If you save rides on Strava you can ask it to correct the elevation - not sure it's anymore accurate than your Garmin but it's different. When I road up to Clingman's dome a couple years ago from Cherokee and from Pigeon forge, having Strava correct the climbs increased the ascent vs my 510. When I correct my weekday rides Strava says the climbing is less.
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  16. #16
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    Quote Originally Posted by Srode View Post
    If you save rides on Strava you can ask it to correct the elevation - not sure it's anymore accurate than your Garmin but it's different. When I road up to Clingman's dome a couple years ago from Cherokee and from Pigeon forge, having Strava correct the climbs increased the ascent vs my 510. When I correct my weekday rides Strava says the climbing is less.
    Strava and other online mapping sites use topographic maps to estimate altitude, so when you "correct" your elevation in Strava, Garmin, and others it uses these data points as reference. The problem is that it can only use data points that it has and these may not actually be where you rode (top of a nearby hill, bottom of a gully etc) and can wildly over or underinflate your actual VM gain.

    There is a regular loop we do, roughly 28km and 540m gain. Time and time again over multiple Garmin devices for the past 6 years it has been this +\- 20m or so. If you "correct" the ride it becomes about 830m and all of a sudden there are downhills in the middle of 100% uphill segments. Corrected rides also generally have quite "noisy" looking altitude graphs. The only time you should really correct an altitude profile recorded by a barometric device is if it is effected by a weather front moving through and gives some wild readings, otherwise they are generally fairly accurate.

    Of course the variances in correcting altitude also depends on the accuracy and number of data points in the areas where you ride.

    having said all that, I believe Strava has recently started to leverage off actual users rides and started to build their own profiles for segments which are more believeable than before. Not perfect, but better, at least where I ride.
    Last edited by TmB123; 05-09-2017 at 01:48 AM.

  17. #17
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    True, I have seen some 20%+ grades reported on Strava where they are relatively flat, 1% at most. It wasn't obvious to me though that they were included in the ride ascent calculation - perhaps they were.
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  18. #18
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    Here's an example of the same segment corrected and uncorrected. There are no downhills in this segment! All the extra up and down adds to your cumulative ascent.

    Why does my Garmin 510 overstate elevation gains?-image.jpeg



    Why does my Garmin 510 overstate elevation gains?-image.jpeg

  19. #19
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    My dads old 510 always gave him a more ft of climbing vs what I would get on my 1000 (1247 vs 945 on a shorter ride for example). His current 1000 gives numbers that are relatively even to what I get on mine. No idea what causes it though.

  20. #20
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    Both the 510, 520 as well as the 800 and 1000 series of Garmin products have an on board barometer which is responsible for measuring minute pressure changes and recording vertical elevation.

    No worries though, here's a fool proof way to resolve any Garmin related issues you may be experiencing:

    Step 1: Locate bathroom
    Step 2: Open door and enter bathroom
    Step 3: raise toilet bowl cover
    Step 4: drop Garmin into bowl
    Step 5: flush
    Step 6: laugh manically
    Step 7: check to see if bowl is empty if not give the Garmin unit good heel stomp of compliance
    Step 7: locate nearest PC
    Step 8: Order Wahoo Bolt
    Step 9: go ride yer bike

    Actually, I have no data on Bolt elevation vs Garmin's (though I suppose DC rainmaker does!) but good riddance nonetheless.
    "That pretty much sums it up. I'm 43 and my max is ~178-180. If that HR chart was mine or Froome's, we'd be on the verge of death. But for you it probably looks like a normal workout." -TLG

    LOLOLOL

  21. #21
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    Quote Originally Posted by Jwiffle View Post
    Your hearing the wrong explanation. Most of the Garmin units use a barometric altimeter, so they'll never do what you're describing. Maybe some of the lower units that don't have barometric altimeter will do that.
    Here's an anecdote for you: I live by a long suspension bridge that joins NJ with NY. This bridge has a foot/cycle path. My 510 wasn't configured to ignore baro data and my strava does not auto correct. Still, at the end of the ride I would get a 300-400 foot bump in elevation totals.
    "That pretty much sums it up. I'm 43 and my max is ~178-180. If that HR chart was mine or Froome's, we'd be on the verge of death. But for you it probably looks like a normal workout." -TLG

    LOLOLOL

  22. #22
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    Same route - Edge 500 vs Wahoo Bolt. A massive difference of 27 ft.



  23. #23
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    Quote Originally Posted by 9W9W View Post
    Here's an anecdote for you: I live by a long suspension bridge that joins NJ with NY. This bridge has a foot/cycle path. My 510 wasn't configured to ignore baro data and my strava does not auto correct. Still, at the end of the ride I would get a 300-400 foot bump in elevation totals.
    That's because when you go from NY to NJ you get high; when you go from NJ to NY you get higher.
    Ballan, we have a problem.

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