Race 2: GPS and distance accuracy vs previous Suunto models
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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.
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@maszop said in Race 2: GPS and distance accuracy vs previous Suunto models:
Strava just analyze raw data itself.
Therefore there are different values for distance, speed, duration/pauses, etc.Speed and duration - yes Strava recalculates these using their moving time algorithm. But distance comes as is without any change other than rounding when data is imported as a FIT file. If you do distance correction on Strava, only then it would recalculate the distance as a sum of distances between consecutive track points.
I received this information directly from a Strava dev. I am fairly active on Strava community hub.
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@sky-runner Thanks for information. I thought Strava was processing everything itself.
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I just compared some of my biking activities and I did not find any (significant) difference in distance between S9B and SR2. If there is a difference, it is less than 10-20 m in a 50 km ride. But such difference can easily be attributed to taking a slightly different course on a number of corners or curves.
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@MdzOtt Cycling is handled differently than pedestrian activities. It is much easier to calculate distance from cycling as speeds are faster and any deviation in the GPX trace from a bad GNSS signal is minimized since the points are farther apart.
What @jjpaz has pointed out is that something has changed in the way running distance is calculated. It is no longer derived solely from GPX distance.
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Yesterday’s test results, after the January update. ~10km flat run, steady easy rithm, linear route, out and back along the same route:
- Vertical 1. Watch showed 10.18km. GPX file distance 10,18km. Strava corrected distance 10,18km:
- Race 2. Watch showed 10.10km. GPX file distance 10,21km. Strava corrected distance 10,20km:
So, although difference is less than in previous activities, the behavior is the same. Race 2 shows less distance (~1%) than Vertical/RaceS and tracks are less accurate, with more difference/separation between lines (Vertical tracks are more “aligned”).
Race 2 is a good watch, GPS accuracy is good altough It doesn’t seem as accurate as its predecessors, and other competitors watches, in terms of GPS accuracy. Similar results regarding accuracy are also mentioned in some of the online reviews.
I’ll test again this weekend in hilly terrain, which seems to show more differences, and I’ll make a decission. -
J jjpaz referenced this topic
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@jjpaz
Yesterday I tested the behaviour of the new firmware on terrain with a bit more elevation:
Race 2 v2.50.26
Distance: watch: 13.15km, GPX: 13.40km, Strava corrected: 13.40km
Ascent: watch: 1023m, GPX: 1048m, Strava corrected*: 1003m -
After 3 activities after firmware update, it seems that both watches are closer in distance, altough Race2 keeps showing less distance (around 1% less).
Example from saturday run, ~12.4km, flat easy run.
- Vertical: showed 12.41km. GPX file 12.42km.
- Race2: showed 12.30km. GPX file 12:43km:
According to GPX file data, both watches recorded similar GPS points, laps and distances. If you compare GPX data track, very very very similar.
So, I use Garmin Connect to compare the FIT files downloaded from Suunto App, with the activities data from watches. This is the comparison result:
Distance is different (as shown in every watch) but, if you push the “play” button to show the 2 tracks in “real time”, they are practically equal in all the activity, similar positions, altitudes,…
So, it seems clear that every watch algorithm is calculating different. Which of them is more accurate? Is Race2 cutting distance or is V1 adding distance?
On sunday, similar behavior. 100m difference in 10K activity. Both tracks where similar and both GPX files very very close (I finished activiy in Race 2 several seconds after V1, so 20-30m more distance added in comparison).
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@jjpaz Thanks for posting these results and continuing to dig into this topic. I find it quite interesting since I used to think that Suunto watches, in general, measured just a bit long. There was a time when Suunto’s GPX traces were a bit “jiggly” (some people referred to it as “zig-zagging”) and the assumption was that these wiggles added a slight increase to an activities overall distance.
However, over the past year, beginning with software 2.39.20, a fair amount of smoothing has been added to the traces and I’ve come to regard Suunto’s distance accuracy among the best. (I commented on this change over here. You’ll notice in the example I gave how the Vertical added slightly to the GNSS distance, presumably due to 3D distance, and the 955 subtracted from it, presumably due to the applied algorithm based on pace, cadence, stride length, etc.)
I find it interesting that, after working so hard to perfect their GNSS accuracy and tracing, Suunto has chosen to apply further distance calculations based on… who knows.
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I may have to backtrack my observation that Suunto used to use GNSS distance alone to calculate activity distance. I just went back and looked at some older “Running” and “Walk” activities (using the new & improved Quantified Self) and noticed that sometimes activity distance was actually shorter than GNSS distance, even for older models like the SV1, 9PP, and even 9P. Not by much, perhaps only 20-40m over 5km in certain cases, but something nonetheless.
I’m mostly a trail runner, though. For these activities, GNSS distance and activity distance almost always align or activity distance is slightly longer due to elevation gain/loss.
Perhaps all Suunto watches do share the same distance algorithm (which makes sense), but the newer models are registering less-accurate GNSS accuracy and therefore applying more distance correction?
