Suunto 9 – Altimetry Accuracy over 200+ miles

I’m not going to be able to do any proper mountains until trips in the summer and after the summer. So all I have for now is a modest 500m ascent on MTBs over 13 hours on mud and trail with the new Suunto 9. Edit: added in another 100-mile plus ride with 2km climb

Ride 1

Suunto 9 altimetry

Something strange happened with the elevation at 10:10:26. At that point we were stopped, fixing a puncture.

At the same time Movescount, below, seems to show there was a notable air pressure change. So I’m not sure exactly what is going on there. The rest of the track looks good to me.

If I then add in the elevation track from the Forerunner 935 for the same ride you get the chart below. First up, ignore that it wasn’t auto-calibrated at the start for the correct elevation. But you can see that there is drift on the 935, probably linked to the atmospheric pressure changes mentioned earlier. Bizarrely the 935 ends up at the same elevation as the Suunto 9.

Climb/Descent Stats are:

  • The 935 recorded +628, -602m
  • The Suunto 9 recorded +606, -571
  • ‘Correct’ was +582, -567

Ride 2

Finally, and probably more definitively, here  is a 2km vertical and well over 100 mile horizontal ride comparing 4 devices ;-). Of interest to me was that this ride started away from home, I faffed around at the start before actually moving off and that seemed to give all the devices a relatively decent chance of working out the altitudes which were even relatively similar at the end where the ride finished in the same place. My uderstanding is that you need to wait AT LEAST a minute after getting a GPS fix in order to let your GPS fix also get a 3D fix for altitude/elevation.

The following results from all the devices seem pretty good and pretty consistent amongst themselves. Variations are somewhat masked by the number of data points over the 8 hours as well as by the number of lines on the chart. The Wahoo seem to have the most variation from the other with Garmin having the enxt most variation. Once again that leaves Suunto and Polar with what might be the most accurate tracks (I sense a trend 😉 ).

suunto wahoo polar garmin elevation

Let’s look at the exact same chart but this time comparing JUST the Suunto 9 with the ‘correct’ track

 

Climb/Descent Stats are:

  • The 935 recorded +1552, -1482
  • The Suunto 9 recorded +1776, -1767
  • The Polar V650 was +1786, -1773
  • ‘Correct’ was +1876, -1866

 

Take out: For my own purposes I’d be happy with any of these data. However for those of you with more of a need for precision I might tentatively offer that the FusedAlti of the Suunto and, perhaps, the quality of the internal componentry together deliver a usable track.

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Justin
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Justin

I mean to be completely honest here, neither is on the mark but the swing is much larger between the “actual” and what the Forerunner 935 produced (approx 40m difference). The 9 is eerily close to the actual and that’s with a device out of the box before fine tuning (via hotfixes and firmware updates). Not to mention the 935 is over a YEAR old now.

Color me impressed–just with the accuracy, the lacking package of Suunto at large and that demonstrable price tag is doing it no favors.