Endurance around the Traunsee – Testing the Suunto 9 FusedTrack

At this year’s mountain marathon around the Traunsee lake (Bergmarathon “Rund um den Traunsee”), I decided to have a look at the Suunto 9 FusedTrack, as used in “Endurance” battery mode and thus “good” GPS.

For comparison, the Suunto Spartan Ultra also ran on “good” GPS, an Ambit3 Peak and GPS TrackPOD on best GPS.

Not quite 70 km are still nothing for the Suunto 9 battery, but still, it’s too good a chance for highly variable conditions…

Bergmaratho: All the Tech
Bergmarathon: All the Tech. Can you find it all? 😉

Battery Advice

The Suunto 9 gives battery runtime estimates before you start an activity recording, while choosing the battery mode you want to use… and it’s slightly absurd.

I knew I wanted to try out, thus picked, the Endurance battery mode.

On a Suunto 9 still at 92% battery. Meaning it showed me a runtime estimate of 36 hours.

Even on bad days, I never needed more than 14 hours for that tour, so I could just as well have gone for Performance mode / best GPS…

This is what still makes me wonder about the battery runtime as *the* sales argument, because “you will never run out of battery”. During training runs, this has never been an issue for me.

Anyways, that’s not the point here and now.

The Trouble with FusedTrack

What had me concerned about the track recording with FusedTrack is that this feature only works in running modes (“Running” or “Trail Running”).

The algorithm for FusedTrack is set up, to the best of my knowledge, to work with the oscillations the watch gets from a running motion, at speed.

But then, the extra-long battery runtimes made possible by the low GPS fix rates and FusedTrack recording are for extra-long tours.

Tours and races which will entail a lot of climbing that will not be at running pace. A lot of walking in between.

This edition of the Bergmarathon, I also had a bit of a pain in my knee, thus decided to finally use my trekking poles again. Meaning, I added a different kind of arm movement / oscillation into that mix.

Bergmarathon 2018: Muddy Downhill
Through mud, with trekking poles… very different from a standard running motion

The track also goes over some mountains, climbed on what amounts to simple Via Ferrata, not just running trails.
Through dense forest on mountain slopes.
Alongside rock faces.
Through some tunnels.
Into valleys.
And over roads with an unobstructed view of the sky.

Perfectly bad conditions to check what FusedTrack can or can’t, currently, do.

I was surprised.

Track Comparison 1
Track Comparison 1: At the resolution/zoom where Google Maps shows terrain data. Not bad, here.

Suunto 9 FusedTrack Performance

There are still good sides and bad to GPS + FusedTrack.

With GPS points updating location only every minute, pace is relatively useless (and something I am, admittedly, hardly ever looking at on GPS watches, anyways, least of all in events and with GPS use like this).

Disturbed GPS signals are a major issue; if the one location fix done in a minute does not work or, perhaps even worse, puts one in the wrong place because of bad signals and reflections, the track ‘painted’ by FusedTrack continues from that wrong place.

Tunnel No-Vision

The tunnels at the foot of the Traunstein were one place that made this very visible.

Track Comparison 2 (Tunnel Issue)
Track Comparison 2 (Tunnel Issue). Suunto 9 in green. Track veers off just where the tunnel begins, iirc

The Suunto 9 got pretty misled there, and the trail of the Naturfreundesteig up the Traunstein apparently did not let it get good enough a location fix to recover until I was up that peak.

Winding Trails

In general, unsurprisingly, the Suunto 9 cannot follow twisting mountain trails very well, even with FusedTrack.

Track Comparison: Satellite Image, Daxnersteig
Track Comparison: Satellite Image, Daxnersteig

It did take the “best” GPS to do that – and Ambit3 Peak and GPS Track POD still, as one would expect, showed some difference in tracks.

Suunto 9 FusedTrack ‘Freakout’ #2

The second time the Suunto 9 got completely misled, I have no idea what happened. Nor do I see any reason why it should have happened.

It was in a bit of a forest, but nothing any worse than before. In fact, GPS visibility should probably have been better there, having crested a slope and reached a somewhat wider forest road…

Track Comparison Suunto 9, Fused Track Issue 2
Track Comparison Suunto 9, Fused Track Issue 2

Suunto 9 FusedTrack vs. Suunto Spartan “Good” GPS

The interesting thing and the intention behind FusedTrack is “only” to provide better GPS tracks than “good” GPS alone.

Here, in spite of the freakout at the tunnels and one other time where, for no apparent reason, the Suunto 9 went off on a tangent, the result was interesting:

I was fully expecting the Suunto Spartan Ultra’s “good” GPS, still providing 1 second fixes, if not on full power all the time, to achieve a better track than the Suunto 9 with its GPS fix rate of 60 seconds and FusedTrack measuring the in-between.

Track Comparison: Ebensee (Road, High Visibility to Sky)
Track Comparison: Ebensee (Road, High Visibility to Sky)

Actually, much of the time, FusedTrack worked considerably better than the Spartan’s “good” GPS, which also took quite a few detours on those tracks…

Comparing the overall measurement, it is all quite odd.

Overall Distance Data

Suunto 9 ended up measuring a
total distance of 63.72 km
ascent 4359 m
descent 4351 m

Suunto Spartan Ultra
total distance of 58.73 km
ascent 4500 m
descent 4507 m

Suunto Ambit3 Peak
total distance of 61.04 km
ascent 4507 m
descent 4507 m

total distance of 58.29 km
ascent 5147 m
descent 5053 m

What is really quite odd here is the large difference in distance between Ambit3 Peak and GPS TrackPOD.

I have not been finding that setting anymore, but would not be surprised – and it would well explain this difference – if 3D distance had been counted by the Ambit3 (and not the GPS TrackPOD or the Spartan and Suunto 9).

Track Comparison 6: Satellite Image at the End
Track Comparison 6: Satellite Image at the End

Anyways, even though the Suunto 9 did not count (or at least, not show) many of the small twists and turns, had its two freak-outs where it went completely off-track, it was typically (and finally), rather closer to the Ambit3 Peak than I would have ever expected it to be.
(Yes, it counted more than 2.5 km more than the Ambit, but then, the Spartan Ultra fixed a track point every second, and counted 2.5 km less…)

Officially, by the way, the Bergmarathon counts as a 70 km distance event, but it is well known that the actual distance is somewhere around 65 km or a bit less. Which fits.

Altitude Measurement

Altitude on the GPS TrackPOD is only coming from GPS, thus it is to be expected that it is off from actual (and barometrically measured) altitude.

The Suunto 9 somehow had an issue mainly on the ascent of the Traunstein.

Altitude Profiles from Suunto 9, Spartan Ultra and Ambit3 Peak
Altitude Profiles from Suunto 9, Spartan Ultra and Ambit3 Peak

It is clearly visible in the altitude profile where it somehow did not count a further ascent but a plateau; it looks like some pressure change failed to be interpreted as the ascent it was.

Thus some 150 m of ascent (and descent) went missing which were well recorded by both Ambit3 Peak and Spartan Ultra.

(All watches had been set to the correct altitude at the beginning, by the way.)

In absolutes, the Suunto 9 showed me at a
highest point of 1568 m and a lowest of 424 m.

The Ambit3 Peak:
highest point of 1574 m and a lowest of 427 m.

Suunto Spartan Ultra:
highest point of 1578 m and a lowest of 426 m.

That is all quite well, but even the GPS TrackPOD got that quite alright at a
highest point of 1577 m and a lowest of 410 m.

Heart Rate Measurement

Heart rate was not my focus here; longer events like that are better run without it, anyways…

And looking at what the oHR on the Suunto 9 here often measured, it would definitely be better to run without it.

Overall heart rate, Suunto 9 (oHR) vs. Spartan Ultra (HR belt)
Overall heart rate, Suunto 9 (oHR, green) vs. Spartan Ultra (HR belt, blue)
HR Measurement at the beginning
HR Measurement at the beginning. One can see that things didn’t start off too badly, but then the oHR got very disturbed

The pulse it thought I was at often differed by 60 bpm from the one measured with the HR belt…

(There are known issues with oHR, where walking cadence is picked up as heart rate. Maybe this is, at least part of, what’s to blame. It is being worked on.)

Well, oHR definitely could improve, will be improved – but is also notoriously unreliable, no matter what sensor is used. And the Suunto 9 uses a very good one, actually…

Battery Use

My tour here, this year, ended up taking me 13 hours and 37 minutes; the watches went down…

Suunto 9, from 92% battery to 41%;
Spartan Ultra from 91% battery to 43%;
Ambit3 Peak from 98% to 22% (with best GPS, though).

That does not, actually, sound like the Suunto9 would have lasted for the pre-estimated 36 hours, given it fell by 51% charge during that time…

At least, it would have warned well of low battery and suggested to switch to a different mode, though.


Some work clearly remains to be done with the Suunto 9, FusedTrack and all else.

Still-better GPS fixes, still-better performance at lower speeds and in a wider range of circumstances would be very nice. oHR could perhaps be improved.

The main problem with FusedTrack, though, is perhaps one of the usual problems of user psychology:

We expect technological progress and want to get closer and closer to perfection.

The Suunto 9 FusedTrack, however, deliberately takes a step back from that in favor of alright (“better than ‘good’ GPS alone”, i.e. than low GPS fix rates) GPS tracks and longer runtimes in a smaller watch. And a watch equipped with oHR.

I would still much rather have that watch without oHR and with a battery like the Spartan Ultra, which could easily give runtimes sufficient for three full days (72 hours) of “good” GPS with FusedTrack.

As it stands, the Suunto 9 is not as big a step up from the Spartan Ultra (let alone Ambit3 Peak) as one would expect from a current generation GPS sports watch – but for the ultramarathon runner and apparently, even the ultramarathon marcher, it moves in a very right direction.

And a direction, at that, that other companies do not seem very willing to go into, of specializing rather than trying to create one watch for any and all customers.

It is sorely tempting to get on a trail overnight next, to even try out the “Ultra” battery mode where the Suunto 9 FusedTrack features works with only a 2-minute GPS fix… but I don’t think I want to be gone (or will go) anywhere for more than the ~two days that the Suunto 9 could already record, with better than the Spartan Ultra’s (1 second-fix) “good” GPS, at its good GPS / performance mode…

2 responses

  1. Brad Avatar

    Gerald, I see you had yet another watch? And, what was the camera you were carrying? Very nice write up. I have not yet seen my S9 freak out. I will be pacing at Hardrock this weekend and may try Endurance mode at slow speed to see how it works.

    1. Watches were as described: Suunto 9, Spartan Ultra, Ambit3 Peak (on shoulder strap).

      The camera is the Sony RX0 I’ve been using as my main camera since last year’s Japan trip. It takes something else for close-ups (and astrophotography), it could use a gimbal even more than the action cam I used before (on runs), but it’s small and light and sturdy, yet capable, enough to be great for all my outdoors/mountain pursuits.

      Endurance mode (FusedTrack) isn’t even supposed to work at slow speeds, afaik…

      Oh, and thank you for the Ko-Fi support 🙂

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