Metric error/differences with direct upload to Strava - but also between GoldenCheetah and Garmin Connect/device

[Giant DK]

When I began to play a little with Strava together with GoldenCheetah I noticed some differences on some of the metrics which annoys me. So I took the same file and compared the metrics between GoldenCheetah, GoldenCheetha’s direct upload to Strava, direct upload from Garmin Edge 800 to Garmin Connect, direct upload from Garmin Edge 800 to Strava and direct look on Garmin Edge 800. You can se the different data below. 

What struck and annoyd me first was the BIG differens in elevation gain, where it looks like the direct upload from GoldenCheetah to Strava makes a mistake when uploading. When I sat down and studdied i more closely I could also see, that GoldenCheetah also doesn’t show the same values as Garmin Connect, Garmin devise and Strava – though not that big a difference. 

I also saw, that Strava shows me to have ridden longer than the others – no matter direct upload or through GoldenCheetah – this must be a “mistake” within Strava. Strava also skews ridetime which together with distance skews the avg speed. But I also noticed a little difference (30 sec) between GoldenCheetah and Garmin Connect/Garmin device. kJ is also not exactly the same. Might because of ridetime and AVG power.

Strava also seems to f@@k the max speed up.

 

So, have anyone else heard of/noticed the error in especially elevation gain when uploading fra GoldenCheetah to Strava?

And what about the other differences (elevation gain and ride time) between especially GoldenCheetah and Garmin Connect/Garmin device? Is this a normal behavior, something that I should worry about or something that I can actually do something about? I believe the ride time as shown on my device when I press stop should be the same as shown in GoldenCheetah (as well a total elevation gain). I know it is just “small” differences but the fact that they shows bothers me.

Hope anyone can help.

 

Distance

Goldencheetah: 70,45 km

GoldenChetah => Strava: 71,30 km

Garmin Connect: 70,45 km

Strava: 71,30 km

Garmin Edge 800: 70,45 km

Elevation gain

Goldencheetah: 1078 m

GoldenChetah => Strava: 1626 m

Garmin Connect: 1137 m

Strava: 1134 m

Garmin Edge 800: 1137 m

Ride time

Goldencheetah: 02:35:07 

GoldenChetah => Strava: 02:39:07

Garmin Connect: 02:35:35

Strava: 02:39:08

Garmin Edge 800: 02:35:34

Elapsed time

Goldencheetah: 02:42:37

GoldenChetah => Strava: 02:42:36 

Garmin Connect: 03:23:10 

Strava: 02:42:36 

Garmin Edge 800: - 

kJ

Goldencheetah: 1753 kJ

GoldenChetah => Strava: 1774 kJ

Garmin Connect: - kJ

Strava: 1773 kJ

Garmin Edge 800: - KJ

Power AVG

Goldencheetah: 188 W

GoldenChetah => Strava: 186 W

Garmin Connect: 189 W

Strava: 186 W

Garmin Edge 800: 189 W

Max speed

Goldencheetah: 73,4 km/h

GoldenChetah => Strava: 79,3 km/h

Garmin Connect: 73,4 km/h

Strava: 79,3 km/h

Garmin Edge 800: 73,4 km/h

AVG speed

Goldencheetah: 27,3 km/h

GoldenChetah => Strava: 26,9 km/h

Garmin Connect: 27,3 km/h

Strava: 26,9 km/h

Garmin Edge 800: 27,2 km/h

[Giant DK]

Thanks a lot for your answer. Here is a link for the activity uploaded from the Garmin device. I have deleted the uploaded file directly uploaded from the Garmin Device, but I can upload it again if that could be any help: http://app.strava.com/activities/26927216  

Yes, when uploaded to Strava I uploaded directly from the Garmin Edge 800 - through "Upload Activity". I have only recorded the distance with the GPS - no speed sensor. And I would prefer Strava to show the same distance as any other application. The same as maxspeed. 

I'm sure it is the max speed that appears in all other programs that are the correct. 

Same goes for elevation gain. You can see that I have climbed a 750 m climb and a 350 m climb on Strava. Everything else was flat. That makes me believe that a elevation gain arround 1100 m is more correct than 1600 m. Is this a upload problem within GoldenCheetah og Strava?

And can anyone explain why GoldenCheetah doesn't show the same elevation gain as the Garmin device?

Thanks:)

[Mark Liversedge]

Our hysteresis factor is more conservative. In truth, you cannot be sure which is correct. But the differences shouldn't be that significant...

[Giant DK]

I just thought it use the recorded elevation numbers from the fit file... I don't think the difference is that big but I just wondered about it anyway.

[Mark Liversedge]

We only worry about elevation changes > 3m when aggregating, so little ups and downs are ignored. For some 3m is too high, for others its about right. Its a perennial question. Maybe we should let the user define it in the options :)

[Giant DK]

That could be a nice feature. Maybe those less 3 m climbs will sum up to the difference in elevatoin gain in the different applications ;)

[d78]

It's an interesting debate however until the accuracy the recording of elevation by the devices is sorted it's really just is more noise. On a 50 mile ride my brother and I can easily see over 800m of elevation difference using the same device, Garmin 500, over the same course in the same conditions. That's an issue across the board on the Garmin's so far as I can tell. I doubt any of the rest are much better.

[Giant DK]

Maybe, I was just interested in the difference in elevation gain, when the different application use the same raw data. I don't care wether I have driven 30 m more or not, but the different values just annoys my eye - if you know what I mean.

But I have never experienced the difference in elevation gain you experience between two of the same devices. Of course there are some difference but all I have experienced is a reasonable difference - not as pronounced as you have experienced.

[Davis Kitchel]

Thanks for the info.

The only reason we'd alter the distance for an activity is if the system found a point or a series of points that were clearly errors in the data which could throw the distance the device reflects off.

I swapped the distance data back from our calculated distance to the distance the device reflects for your ride.

I'll pass your suggestion along about max speed.

Elevation continues to be a tough to get consistent since different algorithms have different thresholds for what is considered true "gain."  It's something we and I assume others will continue to work on.

[Giant DK]

Thanks a lot for your answer!

I understand about the distance now.

Regarding the elevation I understand this is a tough one, but shouldn't the elevationgain be the same from a directly uploaded fil (from device) and from GoldenCheetah, since Strava must handle the data the same way?  The diffencere is a half time bigger on the ride uploaded from GoldenCheetah.