Race 2: GPS and distance accuracy vs previous Suunto models
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Hi, I open a dedicated thread to this topic.
Question to V2/R2 owners who have had previous models:Have you noticed if the new hardware measures less distance in activities than the previous watches?
In my case: I own the V1 and Race S. I’ve been testing the Race 2 for a few days comparing with my previous watches. In all activities, the V1 and RS were virtually identical in distance and kilometer markers. The Race 2 is measuring between 1% and 2% less distance than the V1 in the three runs I’ve done comparing the two watches.
On runs of 9-10km to 13-14km, the Race 2 is measuring between 150 and 200m less (it marks each 1km lap 4-6 seconds later than the V1 or RS). Even in the first kilometer, it “loses” 20-30m compared to everything I have measured, and during the activity, it accumulates more “loses”.
I also notice that the V1 tracks are more stable, as is the pace, especially in boulder fields or forests; it’s more stable in open areas.
To test this, I tried using distance correction on Strava for activities with both watches, and with the V1 and RS, there’s practically no correction. Strava gives the same distance as the watches did. With the Race2, Strava adds the 150-200m difference compared to the previous watches.Is anyone else experiencing this? I’m going to compare a couple more activities and see if I can compare tracks. Yes, I know that 1-2% difference is small, but it’s curious that the two older watches were so similar and this one deviates more. I suppose the hardware change has been more significant and could be the reason.
Another detail: when downloading the GPX/FIT of activities from Race2 and putting it into track viewers, the real/3D distance it gives is similar to distance in activities with V1, and the one corrected with Strava, that is, with the 150-200m more.
Examples:
- Activity 1: SV 14,3km (GPX data shows 14,4 real distance). SR2 14,1km (GPX data shows 14,4 real distance). Both tracks and 1km laps very close and similar when showed in GPX viewer but Race 2 shows less distance in the screen during activity and in the activity data uploaded to Suunto App.
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Hi all
I’ve run a couple more tests comparing Vertical and Race 2, as well as the GPX files of the activities.
In all the activities, Race 2 records less distance (and speed) compared to Vertical (or Race S) and compared to the data in the activity file. The difference is a reduction of around 1%-1.5% in flat activities and between 1.5%-2% in hilly activities, and it’s not sporadic or random; it occurs in all the activities.
Therefore, I believe that the Race 2 algorithm underestimates distances and, consequently, paces and speeds, because GPX recorded data is very similar between watches. Or Race 2 is more accurate and the “old” model were overestimating distances.
Examples:
- Hilly running activity: Vertical showed 14.28km (14.30km recorded distance in GPX file), Race 2 showed 14.12km (14.38km recorded in GPX file. In this case I stopped Race 2 around 100m after stopping Vertical). This is a -1.12% difference between watches and -1.80% between Race 2 and his GPX file recorded distance.
- Flat running activity: Vertical showed 9.46km (9.47km recorded distance in GPX file), Race 2 showed 9.34km (9.48km recorded in GPX file). This is a -1.26% difference between watches and -1.47% between Race 2 and his GPX file recorded distance.
- Yesterday flat running activity: Race 2 showed 12.33km, GPX file recorded 12.49. Vertical showed 12.48km.
I compared also in a short flat trekking activity, the difference between watches is around 1.2% too.
Have someone seen this behavior with the new watches? Can someone compare if possible?
Thanks!
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J jjpaz referenced this topic
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@jjpaz How do you know how much a GPX file shows?
Every service and every application can analyze the same file slightly differently. I don’t know if you can get an absolutely accurate distance based on GPS data alone. I think 1-2% accuracy is the maximum accuracy based on GPS. -
@maszop You can use several GPX file viewers or Strava “distance correction”.
In every case, the GPX distance or corrected distance is similar in Vertical and Race 2 but showed distance in screen and activity summary differ 1.5-2% between watches so the algorithm they use is different and then accuracy is different. -
@jjpaz In the past, with a Suunto watch, you had to run a bit further because Strava would slightly reduce the distance. Now it’s almost the opposite. Of course, some algorithm might have changed, but 1-2% shouldn’t matter because the measurement error is probably at least that much.
In any serious applications, GPS is not used to precisely measure distance.
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Looking at reviews of the watch when it was released, some criticized it precisely for not being as accurate in GPS tracking as previous models and for overestimating the actual distance. Perhaps the algorithm was corrected in the November update, and now it reports a shorter distance than the actual distance… I’ve had the watch for a week now, with the November software (and since today with the new update). I’ll test it again against the SV tomorrow.
An example from yesterday activity:
- Suunto Vertical, distance showed in the watch: 12.48km. Distance showed in GPX file: 12.49km.
- Suunto Race 2, distance showed in the watch: 12.33km. Distance showed in GPX file: 12.49km.
So Race 2 is “cutting” distance respect data showed in GPS data file. May be this behavior was introduced with november update.
Furthermore, you can see that the Vertical track seems cleaner in the various curves and loops. I went through the same route several times; it’s a park I do six or seven times, looping around it.
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I have a similar experience. After the November update, I have less distance than the Garmin FR 970. Before the update it was about the same. Now I only take what the watch shows on the display, not in the GPX viewer. We’ll see what happens after today’s update.
I have Race 2
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@maszop said in Race 2: GPS and distance accuracy vs previous Suunto models:
@jjpaz In the past, with a Suunto watch, you had to run a bit further because Strava would slightly reduce the distance.
Strava doesn’t reduce the distance but just always rounds it down when displaying it in the UI. In contrast Suunto or Garmin properly round to the nearest significant digit. The difference never exceeds 0.01 km or mile.
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@sky-runner Strava just analyze raw data itself.
Therefore there are different values for distance, speed, duration/pauses, etc. -
@jjpaz I think you may have uncovered something here. I do not own a newer generation Suunto (SR2 or SV2). However, I very frequently run with two or more watches at the same time and have hundreds of examples comparing different Suunto watches and competitor watches (mainly Garmin).
Suunto has traditionally used strictly GPX distance to calculate total activity distance. This can be verified (as you’ve noted above) by comparing the two statistics using a service like Quantified Self. For me, GPX distance almost always matches activity distance when wearing something like a 9PP or SV1. The one caveat is that certain types of activities will also factor in 3D distance using ascent and descent figures. Typically this will result in a very small increase in activity distance compared to GPX distance, usually something like 10-30 meters over an average trail run with mild vertical gain.
Garmin, like most other brands, uses a far more complicated algorithm to calculate activity distance. I have no idea what the exact parameters are, but it seems to weigh factors like stride length, cadence, and pace along with general GPX trace distance to come up with a final “distance.” This can be good and bad. It’s great because it can compensate for a poor GNSS signal. It’s bad because things like cadence and stride are very personal and always changing. For me, Garmin devices always calculate an activity distance that is shorter than the devices measured GPX distance.
I verified these behaviors with a test a couple of years ago comparing the recorded activity distance of an SV1 versus a Garmin 955 using different GNSS settings (Multi-band vs. all systems vs GPS only). In short, for Suunto, as the GNSS setting became less accurate, activity distance increased due to more deviations in the GPX trace. For Garmin, a lower GNSS accuracy results in a shorter activity distance, presumably because it is relying more heavily on factors other than GPX distance.
All that to say, it looks like the new Suuntos (at least your Race 2) are now using a more complicated formula to calculate activity distance. I don’t have one to compare myself, but judging from your results above, this looks an awful lot like Garmin behavior. This also squares with the fact that most reviews noted a general decrease in GNSS performance for the newer models. So all things are not equal across the Suunto lineup.
One last thought: It looks like you were doing laps in the activities above. Which wrist were you wearing the watches on when comparing them? There will always be a slight offset to the side the watch is recording. That is, a watch worn on the inside wrist will record a slightly shorter distance than one one worn on the outside when doing laps.
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@duffman19 Thanks for your answer.
In the example activity I was wearing Race 2 in left hand, Vertical in right hand but I change direction over loops so I run every loop at least several times in every direction. I call it my “hamster wheel”…
The other days I repeated tests exchanging watches: Vertical on left, Race 2 on right. Same behavior.
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@jjpaz No problem. Sorry that was a lot of words.
Changing directions is the way to go. I do the same and run a loop or path both forward and backward when comparing devices to offset any wrist bias.
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I was comparing to my previouse suunto 5 after i purchased Race 2. Path on map looked much more strait (more correct) so thats may be reason for little shorter distance. I had problem with S5 that while hiking under trees route was too zig-zag and it extended real distance.
