Race 2: GPS, cadence and distance accuracy vs previous Suunto models

[jjpaz]

@gkaempfer said in Race 2: GPS, cadence and distance accuracy vs previous Suunto models:

I don’t see any issue with distance report on my Vertical 2. When I bike, I normally track GPS distance with my Vertical 2 and a Wahoo Bolt (version 2). They report identical distance to the degree of 1/1000 (which is probably me pressing the start while beginning my ride and it’s not exactly at the same time on both devices). I don’t measure runs with another GPS but I wonder if it would be any different.

According to reviews and if you search a bit Strava atletes, Vertical 2 seems more similar to previous models in terms of accuracy. No drastic cuts, measured distances close to GPS raw distances and other devices.

If you search a bit Strava athletes wearing Race 2, that’s a different history. You can see official distances 1%-1,5% shorter than GPS raw distances (and distances measured with other devices) so the behavior is there.

The question is: why this behaviour? It is known by Suunto? I would say that it would be known by Suunto, I doubt that they aren’t aware of this, taking into account sponsored athletes, testers, etc…
Or maybe no one is taking care in GPS accuracy anymore and all the accuracy is centered in the optical HR sensor, who knows!

[SuperFlo75]

@jjpaz my runs with V2 are about 0,5% shorter than those with V1

[Ger43]

@SuperFlo75 not a good news

The most infuriating thing is that in all the reviews in YouTube, not a single person mentions this anomaly…
It’s all well and good to praise the battery, the great display, the myriad of features, but I’d say the GPS accuracy remains the most important thing to review and compare for a sports watch of this caliber.

Today I went for a 2km walk, and when I compared it to the Amazfit, it shaved 10 meters off the 2km mark…

Of course, over 2km, the difference is small, but if we consider the error per kilometer, over a half marathon, the final race pace changes… these are the basics for even a poor runner like me…

Knowing you’re running at 5.00/km when you’re actually running at 4.52 radically changes the perception of running.

I really hope it’s a software bug and that it gets fixed.

[jjpaz]

@Ger43 I wouldn’t worry about 10m in 2km. In my case, I’ve sometimes had differences of 20m per km from the very first kilometer, which would be 200m accumulated over 10km.
5m per kilometer is within a reasonable range for GPS receivers and depending on the surrounding environment.

For example, my yesterday’s short easy run:

Official Distance (Device Summary) 5,322 meters
RAW Distance (GPS Points Summation) 5,398 meters
Algorithmic Reduction (Distance “Clipped”) -76 meters (1.42%)

-70m in a 5K run… This would be ~280-300m in a Half Marathon, and that’s not even mentioning the differences in pace, which are around 4-5 seconds/km (slower) difference

You can analyze your FIT/JSON data to compare official and raw data and check the real difference between those data. In Vertical, Race S, Vertical 2 those data are very close. In Race 2 there’s difference…

[jjpaz]

To add even stranger things, summary of a 17km activity recorded with both Race 2 and Vertical:

So far, this is the usual behavior; Race 2 underestimates the distance measured by GPS, correct?

And now, I go to https://www.sports-tracker.com/ and compare de info and Laps info for every recorded activity and, oh! surprise!, SportTracker shows the “Raw” data and both watches are very very similar in Laps times and Paces (and not during the activity). SportTracker shows 17,3km total distance in laps (the recorded raw distance) and practically identical Laps compared one by one:

[Ger43]

@jjpaz So it’s increasingly clear that it’s simply a “software glitch” and that the hardware is working fine.
Is there a way to send these reports directly to the Suunto developers?
The error seems fairly obvious and verified…

[jjpaz]

@Ger43 said in Race 2: GPS, cadence and distance accuracy vs previous Suunto models:

@jjpaz So it’s increasingly clear that it’s simply a “software glitch” and that the hardware is working fine.
Is there a way to send these reports directly to the Suunto developers?
The error seems fairly obvious and verified…

If you check athlete’s activities recorded with Race 2 the behavior is the same. So, I’m not alone…

[Ger43]

@jjpaz said in Race 2: GPS, cadence and distance accuracy vs previous Suunto models:

@Ger43 said in Race 2: GPS, cadence and distance accuracy vs previous Suunto models:

@jjpaz So it’s increasingly clear that it’s simply a “software glitch” and that the hardware is working fine.
Is there a way to send these reports directly to the Suunto developers?
The error seems fairly obvious and verified…

If you check athlete’s activities recorded with Race 2 the behavior is the same. So, I’m not alone…

I’m reluctantly thinking about returning it…I still have time.
But at this point, if I were to consider getting the Vertical 2, would I have the same problem? Or do you think the V2 is fine in this regard?

[EzioAuditore]

Maybe @dimitrios-kanellopoulos can help. I too am getting less distance and lower pace compared to all other watches. somethimes as much as 170m per 10km (compared to AW3 that I already know is quite conservative).

[jjpaz]

@Ger43 I can’t tell you about the V2; I have the R2 and I’m currently testing it compared to my other watches. Try asking in the V2 subforum, although it seems to be more accurate in its GPS recordings.

[Ger43]

This evening I tried an interval workout… 5x800…
I admit I’m completely lost… this evening, instead of cutting as usual, the Race2 showed me more distance than the Amazfit… already in the first 3km of warm-up, I noticed a pretty clear difference, which obviously affects my pace:

the pace on the repetitions also appears quite distorted between the 2 watches :

but other factors may have also influenced this, for example the START of the 2 watches were not aligned and in any case in general testing repetitions on 2 watches at the same time is not easy… but in the warm-up phase, on the other hand, the difference is quite evident.

The only difference compared to the previous two tests was that in this workout I had installed the map of my region (Lombardy, Italy). Do you think installing the map of the area where I run might have had some impact?

In any case, it now seems exaggerated in the opposite direction. Let’s always assume the Amazfit is telling the truth at this point…

Tomorrow I’ll do the same walking test as the other day. I want to see if the same behavior as the other day (about 10 meters less every 2 km) is confirmed or not.

[Finnjf]

@Ger43 for a bit more detail (and to rule out one possible factor), were the watches on the same wrist / arm? Was this session (including the warm up) on the track? Just wanting to check that the Suunto wasn’t on the outside (right, if running counterclockwise) wrist vs the Amazfit on the inside / left wrist, which could absolutely swing measurements this way.

[Ger43]

@Finnjf said in Race 2: GPS, cadence and distance accuracy vs previous Suunto models:

for a bit more detail (and to rule out one possible factor), were the watches on the same wrist / arm? Was this session (including the warm up) on the track? Just wanting to check that the Suunto wasn’t on the outside (right, if running counterclockwise) wrist vs the Amazfit on the inside / left wrist, which could absolutely swing measurements this way.

Hi, so the warm-up session (the first 3km I posted) was done on the road, while the intervals were done on a loop in a park.
The Race 2 was on my left wrist (outside the track), the Amazfit on my right wrist (inside the track).
But as I said, I don’t consider the interval test very reliable because it wasn’t easy to test. In any case, even in the intervals, as well as in the warm-up, I noticed that the Race 2 recorded more meters than the Amazfit, and this difference was already noticeable during the kilometer.
So far, it’s always been the opposite, although never as marked as last night.
Is there a chance these anomalies will be noticed by a developer or someone at Suunto who can at least verify them?
These anomalies have been reported by multiple users; I find it absurd that no official communication has been received.

[jjpaz]

@Ger43 You can analyze information from your raw data and compare (export JSON or FIT files). That’s the best way to know which GPS points have recorded your watches and what’s the raw distance vs the official ditance showed in watch.

[jjpaz]

@Ger43 You can also review your activity data in https://www.sports-tracker.com/ (the old Suunto App website).
In my case, Sport Tracker analysis: Summary shows 10,20km (official distance showed by Race 2) but GPS data and Laps distances show 10,34km as total recorded distance.

With this data:

Official Distance (Device Summary): 10.201 metros
RAW Distance (GPS Points Summation): 10.334 metros
Algorithmic Reduction (Clipped): -133 metros (1.29%)

Official Pace (Reloj): 5:56 min/km
Actual GPS Pace (RAW): 5:52 min/km
Pace reduction: +4seg/km

Why Race 2 is shortening/filtering the distance? Other Suunto watches are more faithful to GPS data. That’s my question, because it seems obvious that Race 2 records GPS raw data correctly, at least is very similar to other watches but, postprocessing is more agressive.

[Ger43]

It’s raining in Milan today, so I thought I’d test it by placing both watches on my car’s dashboard and setting a cycling activity on both so I could travel at least 30 km/h

This test also confirms everything I said above, that the Race 2 measures meters…here we’re roughly 30 meters out of 5,000.

Amazfit: 5,070 m
Race 2: 5,040 m

This time, however, it seems that the difference is also in the raw file. I uploaded in “Quantifier” website the Race 2’s json file and the Amazfit .FIT file, and it seems that the 5,040 m are also in the json file this time.

My fear is that if I were to return it to Amazon and upgrade to the Vertical 2, I might find myself in the same situation. At the same time, I don’t want to buy the Race1 or Vertical1 models, which are still a step behind the Race2, and aesthetically, I really like the Race2.

This flaw, however, is unacceptable, so I don’t know what to do: wait, perhaps, for an update that permanently fixes this problem, or return it?

[EzioAuditore]

@jjpaz Just speculating here but there might be some other metric taken into account. Usually when dealing with signals there’s the Signal to Noise Ratio (SNR) and maybe there is no difference in FW but the Race 2 has lower SNR and discards more points?

[jjpaz]

@EzioAuditore Good point, because preciselly I noted that distance difference is higher in bad conditions (turns, buildings, forest,…) and lower in good conditions. Analyzing GPS quality data in several Race2 and Vertical JSON files, this is the result:

1. Analysis of Turns and Trajectory
   By comparing the GPS coordinates second-by-second during change-of-direction points:

Wismar (Race2 17,181 m): It tends to slightly “clip” or “cut” the corners. Its smoothing algorithms seem to interpret rapid direction changes as potential noise, drawing a flatter line between data points.

Rostock (Vertical 17,252 m): It records a trace that is more faithful to the actual path. In 90° or 180° turns, the Rostock accumulates between 2 and 4 extra meters per major turn compared to the Wismar.

2. Signal Quality in Critical Zones
   I looked for moments where the EHPE (Expected Horizontal Position Error) rose above 4.5 meters on the Wismar device:

“Accordion” Effect: In sections where the pace dropped sharply or there were technical stops, the Wismar activated more aggressive “auto-pause” or point-reduction filters.

Sampling Frequency: The Rostock (Orca hardware) appears to keep a slightly more consistent sampling rate during high-intensity moments, allowing it to “draw” the micro-variations of the route more accurately.

Technical Conclusion
The Rostock (Orca_RevC1) proves to be slightly more precise in this specific test because:

Its peak EHPE was lower during maneuvers.

Its Path Reconstruction algorithm is less aggressive, avoiding the “corner-cutting” effect seen in the Wismar (Sailfish_RevA1).

So, according to all my tests and analysis, seems that Race 2 algorithm behavior is different… Or is better and other watches overstimate distances or is poorer and Race 2 is underestimating…

[wakarimasen]

An interesting read for all of those suffering GPS distance errors which equate to 1-2% of the total distance travelled.

GPS mileage discrepancies

Even Garmin explains that discrepancies can occur!

Top FAQs About GPS Distance, Speed, and Pace Accuracy With Garmin Devices

I work in metrology and know that comparing different devices can lead to all sorts of confusion and doubt, if a traceable standard is not used as a reference. Unfortunately, neither Garmin, Polar, Suunto or Corus make (or even claim to make) such a device.

I guess it would be interesting to understand how the new watches calculate distance compared to the old ones. It seems that most devices tend to overestimate distances, and maybe some logic has been applied to try and reduce errors which occur due to this.

[Mff73]

@wakarimasen
You will break some dreams that some devices are having THE truth and their 10m more per 5km…