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Elevation bad - off by 20%

Since January 2nd I have started riding in the hills. The rides have been with groups, and my Edge 520 is consistently under-reporting elevation gain by 15-20%.

Example: this morning's 42 mile ride:
1020' - on my Edge 520
1263' - on my iPhone 5s using RideWithGPS app
1299' - friend #1 Edge 810

Another example: 25 mile ride:
2208' - on my Edge 520
2771' - on my iPhone using RWGPS
2703' - friend #2 Edge 810

Two different friends with two different Edge 810s. Seems like a problem with my 520's barometric altimeter. Interested to hear from anyone with good and bad experiences.

0 Former Member over 9 years ago

It's not just your unit. The total ascent algorithm for the 520 tends to knock 5 to 10 feet off of each climb. So rides with a lot of short up and downs will show less gain. Other models may be overstating the gain. Speed change causes change in air pressure which is seen as change in elevation. Sorting real elevation change from noise is the challenge Garmin seems to try something different with each model . The 1000 got the same complaints when it was new and eventually the algorithm was changed. If Garmin gets enough feedback maybe they will update the 520 algorithm. But for now that is the way it is.

Ride With GPS shows a higher gain because it calculates the gain using the data points rather than using the 520 value. Since TCX files don't contain a total gain value, converting the FIT file to a TCX will result in the gain being calculated by any app it is uploaded to.

0 2nfinite over 9 years ago

Thanks. I can appreciate the technical challenge, however I would expect Garmin to keep their bike computers consistent. Its ridiculous that the 810 and 520 differ so much on the same ride.

0 slichten626 over 9 years ago

Four rides over the same course, two using 500 and two using 520 (not done at same time since 520 was acquired after 500 wore out).

The elevation gains recorded agree to within 65 feet -- with total elevation gains of 2739 to 2805 feet. This is a 32-mile ride which takes slightly over 2 hours.

Garmin 500:
32.28 mi Distance
2:14:49 Time
2,753 ft Elev Gain

Garmin 520:
32.01 mi Distance
2:25:19 Time
2,756 ft Elev Gain

Garmin 500:
32.29 mi Distance
2:24:17 Time
2,805 ft Elev Gain

Garmin 520:
32.13 mi Distance
2:17:52 Time
2,739 ft Elev Gain

0 2nfinite over 9 years ago

Another ride, on this 35 mile (time: 1:55:41) ride my 520 was consistent with GC Elev Correction and other riders:

1860' - baseline - my 520
1911' - 3% higher - my 520, GC Elev Corrected
2166' - 16% higher - my RWGPS
1969' - 6% higher - Chris' 810
1965 - 6% higher - Bryant's 810
2001' - 8% higher - Luis' 810
1986' - 7% higher - Dave's Strava Android

0 attackuntiltheycrack over 9 years ago

edge 810

The Edge 810 i had was the worst device Garmin ever released. I wouldn't rely on any data from that device. Horrible, just Horrible.

0 2nfinite over 9 years ago

The Edge 810 i had was the worst device Garmin ever released. I wouldn't rely on any data from that device. Horrible, just Horrible.

Really?

Saturday Feb 21 ride of 96 miles:
4127' Jonathan's Edge 1000
4633' my Edge 520 (5086' with GC Elev Corrections)
4308 Chris' with Edge 810

Sunday Feb 22 recovery ride of 35 miles:
1703' Jonathan's Edge 1000
1821' my Edge 520 (1928' with GC Elev Corrections)
1952' Chris' with Edge 810

>10% difference between high and low elevations recorded. Jonathan's Edge 1000 consistently under-reports 9 out of 10 rides, and then 1 ride is consistent with other riders. I've seen more consistent behavior from riders with 810 than 1000 or my 520.