Total Ascent

My three rides so far with the 1040 indicate that the reported total ascent is about 10% less than that reported by the 1030. I have been fairly comfortable with the 1030's numbers as they are usually very close to the elevation gain reported by Google Earth Pro when I import a gpx file and view the profile.

I wonder if Garmin are using the previous algorithm to smooth the height data which is over-smoothing the more accurate height data created when using the multi-band GNSS option.

Has anyone else compared their total ascent data?

  • I have. I had garmin create a route for me. It was 150 miles, 6500 feet of elevation. By the time I finished the ride, total elevation was 9500 feet. It seems it jus t didn’t register some climbs. It shows flat green on the ride profile, while I’m climbing 6% hills. 

  • I think it's impossible to match the actual elevation recorded against the pre-ride profile. It is b'cos of the pre-ride profile depends on geo data in the map file while the actual elevation recorded is based on barometer, which is very likely affected by actual weather.

  • I agree, there’s no way to match the exact elevation on the pre ride profile. But the discrepancy shouldn’t be so vast. Stravas route creator is very close when compared to pre ride vs actual ride. 

  • Garmins have always had variations. Someone I ride with always had their 1000 give more elevation gain on the same ride than mine.  Up to around 100m in 2000m. Then when we both had 1030, mine read higher. Now I’ve the 1040 it read lower than his 1030.  It was about 20m down in 3000m. It’s the same with other brands. I’ve seen people also with wahoo’s do the same ride as me and gain way more elevation- hundreds of meters.  Since it’s all based on barametric pressure you can hardly expect exact results. It’s actually always not that bad considering.  

  • My favorite example is a couple I ride with, who do tandem rides with both of their Edge units on the same bike.  He will sometimes have more ascent than she does. And sometimes, her distance is greater than his.

    I also notice this when I upgrade Edge units (1000 to 1030, 1030 to 1030 Plus, etc.).  I will put the new unit on the out-front mount, and the old unit in my pocket.  Some results are identical, others vary.

  • Sample rates, using gps only for distance…. Lots of things can cause variations. Often if you actually work it out as a % it’s very close by percentage.  100m in 2000m seems a lot, but I think 5% out of barometric altitude is pretty good. On the 1000 which was always under I used Strava’s altitude correction.  Garmin connect seems to have something similar. Always gained me a good few metres. I stopped using it the 1030 when I lost metres!

  • I’ve found that my elevation is very close to reality. The 1040 has a barometric altimeter, and it is sensitive to environmental factors specifically barometric pressures which can change rapidly due to weather and will have noticeable impacts on total ascent/descent and altitude ASL (or BSL if you’re in Death Valley) once it has calibrated with the GPS (GNSS) at the start of the ride.

  • Hi all,

    Is all this discrepancy to do with the mapping info?

    I've just created a short route on Quo using OS 1:25000 map, and exported the route as a gpx and gdb.

    If I import the Garmin gdb on to my eTouch25, it displays the route Total Ascent as 409 m, but if I import the gpx into OutdoorActive, it shows the ascent of 242 m.

    Since it's only a paper-based plan, no gps errors can be the cause of this discrepancy! Which one is right? 

    I intend to log the ride and see what the resulting track says using Outdoor Active, Strava, Mahle, Garmin and back to Quo.

  • Route planning altitude gain has so many variations i don’t expect accuracy, just an idea of what it will be. Strava route planning seems reasonable.  Garmin course planning is generally quite a bit under. Then you do the ride and depending on the device / brand you get another result!  It is ultimately what it is. A flat ride, hilly ride, or what was I thinking ride…. 

  • This seems to still be a problem.  Not much talk of it online.  I am running 14.20 now and with the laundry list I was hoping it was fixed but nope.  Same ride i do with a 830 and buddy with 1030 get 2800 or so I will have 2350-2400.  Thats a big difference to me.  My epic will show around 2800.   The is well over 10% difference.  I’m just posting to update this and subscribe to the thread.