getting too much ascent / descent on flat routes

[surfboomerang]

@sky-runner the watch is cleaned after every activity and the baro sensor looks clean.

Wind could be a factor, but I checked a bit further back in history and the last 10 runs before the firmware all show a relative flat line like in the first graph.

[MatthiasKlug]

As @Dimitrios-Kanellopoulos suggested in https://forum.suunto.com/post/183086 i wanted to with additional data (however i am using a race 2 not a vertical 2):

I ran a flat route (track training) - to give you an impression:

With the latest firmware the watch tracked 16m ascent / 0m descent, see picture and .fit file:
Running_2026-01-08T17_37_59.fit
This corresponds with the latest firmware 2.50.26 (altitude and temperature):

For your reference the former firmware was working fine:
Running_2025-12-18T17_41_36.fit
This corresponds with the former firmware 2.48.16 (altitude and temperature):

I couldn’t upload the json files for some reason, please note that i will return to the track on thursday (and most likely every other thursday) so just let me know if there is a setting that i should try and if you need additional infos/data.
Thanks to @GiPFELKiND for opening this thread

(edit: is there a way to scale the pictures somehow? maybe someone can move this thread to ‘watches’ instead of the specific ‘vertical 2’ thread, since this is (i guess) more realted to the firmeware for all watches, rather than a specific watch, thx)
(2nd edit: for my run on the track 2026-01-08 there is potentially additional data available, another race 2 user (same day, same track, and similar training) ran with a race 2, firmware 2.45.16 (NO update that day for him), if that helps)
(3rd edit: i was looking how to downgrade the firmware and found some advice how to (see https://forum.suunto.com/post/159509), cool, it explain how to reach a ‘secret’ DEBUG menu, there ist an option called Algo Logger, so just let me know if using this option could be beneficial )

[Dimitrios Kanellopoulos]

@GiPFELKiND you barometer had noise and ups and downs. So this is not due to the update fyi. WE analyzed the data.

About the other one activity I see fused alti kicking in and that created the ascent. Lets see how this goes need more info

[MatthiasKlug]

@Dimitrios-Kanellopoulos today i ran an identical training on a (flat) track, there are 3m in ascent. Compared to former firmware unfortunately not better.
However If the effect ist die to fused-alti, could this fused-alti bei improved to be as good as before?
Here ist the data
Running_2026-01-15T17_41_32.fit

The (flat) track:

the altitude, this time just a bit off, but still off:

The altitude stats in numbers:

highest point 150 m, lowest point 143 m, ascent 3 m, now lets me wonder if the change in the initial threshold from 3 m -> 2m and meter by meter measurement afterwards does mess numbers for this case?

[GiPFELKiND]

@Dimitrios-Kanellopoulos thank you for your information.

[GiPFELKiND]

@Dimitrios-Kanellopoulos said in getting too much ascent / descent on flat routes:

@GiPFELKiND you barometer had noise and ups and downs. So this is not due to the update fyi. WE analyzed the data.

What can i do now? Where the noise is come from? My Sensor is Clean. Thank you for your informations about this

[Dimitrios Kanellopoulos]

@GiPFELKiND nothing. It could be one off or just some water before. If it persists then pm me.

[Dimitrios Kanellopoulos]

@MatthiasKlug the fused alti has not been touched. This is expected and it’s ok for 3m. For the time being that is.

[runomatic]

@GiPFELKiND I’ve always had this happen (with both SUUNTO and Garmin watches) when I run along the beach on a North Sea island. It varies depending on the wind and weather. The stronger the wind, the greater the altitude. The barometer seems to get a bit confused.

[MatthiasKlug]

@Dimitrios-Kanellopoulos …
but … but … but - it was better before
(and now i can no longer mock the guys that have ascent on a track…this makes a bit sad)
If this is expected, i will be tolerate this expectaion, but still sadly I konw that suunto can do better.
Anyway thanks for your effort on that end.

(edit: my first thought was that this behaviour is somehow temperature related (the bigger the temperature drop the higher the ascent) i just wanted to mention this, we will see if the outer temps get warmer and closer to the changing room, so there is less temperature drop)

[HonzaS]

Just returned from first run after few months. I tried 5km track run activity on 200m oval 2nd lane, so 208m but that that’s not important. I got 15m descent even on flat track. Don’t know, if it was better before 2.50.26 FW, but according to charts, it seems temperature correlated. At home, I put the watch on jacket sleeve, so the watch temperature was gradually decreasing outside, but not to ambient temperature, which was about 1°C. And the elevation chart curve seems to copy the temperature chart.

[Sportsfreund]

@GiPFELKiND Switch off the Baro Mode.

[GiPFELKiND]

@Sportsfreund you can not switch off the Baro mode

[Sportsfreund]

@GiPFELKiND Das konnte man doch mal wählen. Finde die Einstellung auch nicht mehr.

[sky-runner]

@GiPFELKiND I’ve observed too much ascent / descent today. It exceeded the expected ascent / descent by about 20-25%.

The issues can be best seen on Strava elevation profile which uses distance on X-axis:

This run was on a suburban terrain which for the most part is mild - there are certainly no sharp changes in elevation that we can see on the profile. The weather wasn’t particularly windy either.

[Egika]

@MatthiasKlug said in getting too much ascent / descent on flat routes:

@Dimitrios-Kanellopoulos …

(edit: my first thought was that this behaviour is somehow temperature related (the bigger the temperature drop the higher the ascent) i just wanted to mention this, we will see if the outer temps get warmer and closer to the changing room, so there is less temperature drop)

From my experience with the altimeter, it actually is not 100% temperature compensated.
I found this when climbing indoor without GPS.
I did 3 consecutive climbs in the second half of the recording. I might have gotten warm and the altitude is shifting downwards:

[jjpaz]

Today’s activity. 17km almost flat at sea level.
Race 2 measured 69+/67-… Yes, it was windy but Vertical measured 85+/85- covered by sleeve.
It seems that new algorithm is adding meters in the little altitude oscillations. In my graph there’s a lot of 1m variations (0m, 1m, 0m, 1m, 0m, 1m,…), are these little 1m differences added to the whole acumulated ascent? Is the only reason I find to this behavior in a almost flat route (maybe 5m+ or 10m+ acumulated in total?)

[sky-runner]

@jjpaz Small oscillations in altitude aren’t necessary added to the ascent and descent. There is a threshold. The best way to observe that on the watch is to have a custom data screen with the altitude field side by side with ascent and descent fields. These fields don’t change at the same time.

[Niclas Brundell]

I have the same issue with my vertical 2. I get 40m elevation gain instead of the 15m my vertical 1 got on a flat trail

[sky-runner]

@GiPFELKiND Potentially related thread:
https://forum.suunto.com/topic/14594/new-ascent-calculation-algorithm-is-less-accurate-than-before