Max speed during activity is consistently incorrect

There is a flaw somewhere in the Xert algorithm for determining the max speed during an activity. I am looking at a few activities and in all cases they do not capture the correct max speed data. Not that max speed is important as a real number it does call into question how Xert parses the data. Any other program I use can accurately determine the max speed for an activity. Has anyone else noticed this and if so have you found out why it does not seem to pop up on the forum.

Which programs do you compare it with? They all use their own algorithm, so even if you do the exact same course on one, you may get another to calculate something else.

This also depends on the settings in each of them.

I take it you are not comparing Xert’s calculation to Zwift or another ‘real life video’ or ‘virtual ride’ program. But even if you use an app that has no course and takes relative speed from a flat, windless track, Xert may give a different outcome compared to TR or the Sufferfest.

If you have virtually traveled 40 km on Xert and 50 or 60 on any other app, while the elapsed time is the same, using the same parameters, I would question either calculation. Max speed, not so much…

Thanks for your thoughts, good point I meant to say outside real world rides, I have used, probably 3 different programs, the data comes from my power meter as well as my Garmin both using a hub based speed sensor. Xert sees a max speed usually 20-30 KPH less than the actual max speeds seen on other programs. For instance Golden Cheetah, Garmin Connect, Strava all say about the same thing, but the Xert numbers are drastically low. I have no problem being out 1 or 2 KPH between programs but the case for Xert is drastic.

I wouldn’t mind a few kph on the average, but 20+ kph seems like some algorithm in Xert’s app that removes it as an outlier?

I never use the Xert app outdoors, so I have no reference - I might use the CIQ Xert Player to see if that does the same…

I’m pretty sure it’s not calculated and we use the value provided in the FIT file. Saves on a bit of processing. First time this has been reported.

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not the app but when the ride is uploaded to the Xert platform and Xert does its manipulation of the data to do the Xert thing the data in the Xert activity viewer on the main web site ie
as you can see the avg speed is almost the same as the max speed which is incorrect. This is an algorithm problem that happens when Xert parses the data in the file, somehow it does not capture the max speed correctly.

I have never really looked at that, but now that I did, I don’t see that sort of differences for avg and max, on any ride. Well, unless I do a trainer ride, at fixed power, with no sprints…

The Strava screenshot is the top ride in the Xert screenshot. And only when I uploaded this, I saw the typo :joy:

And here’s the original speed info, from Garmin - looks like Xert takes it from Garmin, which makes sense as that is how I sync it, but Strava calculates something else…

All of my outdoor rides recorded on Garmin 1030 look normal for max/avg speed looking back into last year.
How about disabling the hub sensor on the next ride and see if that makes any difference?
Is this something that could be parsed out using FIT File Tools?

It is probably nothing big, but something I have noticed recently that for some reason all other data programs get the max speed right. It is pretty unimportant in the big scheme of things but was curious if it was me only. The Garmin Connect and other data programs are all correct within +/- 0.1 or 0.2 KPH. The world won’t stop turning but it seems to be an oddity I alone am experiencing my setup in Xert.

Hello, I have the same problem. The maxspeed is equivalent at the average speed when i import a tcx file from Polar in Xert.

In Xert.

In Polar.

Hi Armando, this is a data issue related to Xert, not the file. I have uploaded the exact same file to Strava, Golden Cheetah and of course Garmin Connect. All 3 see the same max speed within fractions of a KPH (is a smallish set of data +/- 0.1 ) so it is definitely not set in the file as far as I can tell. The speed data come from my Garmin speed sensor which works fine and I know hte general number based upon looking at my Garmin as I descend the hill… so this is a quirk that seems to be something I have just recently noticed.