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Average Moving Speed Incorrect

williamvh1984 over 8 years ago

Since a couple of weeks I am experiencing problems with the "Avg Moving Speed" field in Garmin Connect.

Problem description: I start cycling and within 10 minutes I have to stop for a while (let's say an opened bridge or so) so I stop the activity on my Garmin Edge 705 and when I continue I press start again. I only stop and start the activity during long waits, so not at traffic lights etc.. The "Average speed" measured by the device seems okay, but I use Garmin Connect to get the actual average speed where the sort stops are taken out of the calculation (Avg Moving Speed). Unfortunately, this seems to be off the last couple of weeks, giving me extra high average moving speeds. It seems to have forgotten about the time prior to the first stop. So the time measurement started after my first stop, but the distance is measured from where I actually started the bike ride.

Two examples:
https://connect.garmin.com/modern/activity/1812343761
https://connect.garmin.com/modern/activity/1795256232

If you change the chart view from "over time" to "over distance" the two starting points are different on the map. Thus the "Moving Time" is calculated incorrectly and the "Avg Moving Speed" as an effect of that as well. Have been using my Garmin Edge 705 for over six years now and haven't seen this strange behavior before. Seems to me that there is a problem in the Garmin Connect Back-end/Server that analyses the trip.

Anyone experiencing similar issues?

0 williamvh1984 over 8 years ago

The problem seems to get worse, yesterday I stopped my device around 60km and now the Avg Moving Speed is calculated from that stop. So the average moving speeds ends up being 72,2 kph, making this data useless. Here is the data: https://connect.garmin.com/modern/activity/1843633081

Am at a point where I would like to know if this could be a problem in my device, or a problem with the Garmin Connect Server.

Is there any possibility to contact the Garmin Connect Support?

0 TrippyZ over 8 years ago

Switch the Garmin Connect view of your activity to Distance view rather than the default time view in the graph. Examine the speed. The first half is missing. Are you using a speed sensor?

0 williamvh1984 over 8 years ago

Yeah, I noticed part of the information is indeed missing.

I use a Bontrager DuoTrap ANT+ sensor indeed.

It seems that the problem only occurs when the activity is stopped and started.

0 williamvh1984 over 8 years ago

Looked a bit deeper into the problem and sort of managed to improve the problem. The *.tcx file is an XML file and contains a <Track>...</Track> element for each Lap (with TrackSegement Elements in between). This means that when the device is stopped and started in the middle of the activity two <Track>...</Track> element are present. And for some reason the time of the last Track element is only considered when calculating the 'Moving Time'.

To deal with the Incorrect Average Moving Speed I have reduced the XML file to one Track element. This can be done by opening the *.tcx file in a Text Editor (Notepad++ in my case) and search for all the occurrences of '</Track><Track>' and remove those (replace by noting). The end result is one big Track element that contains the whole Activitiy. Then delete the activity from the Garmin Connect and upload the updated *.tcx file again. The Average Moving Speed is now calculated correctly (or at least the outcome makes a lot more sense to me now).