Sometimes when you have more devices around, you may be tempted to compare them just because you can .. this is not meant to be a definitive comparison between these 3 devices (and Stryd, and my iPhone GPS) since I don’t have a certified track available or a measuring wheel but still it was fun.
So, I tried for distance, pace and HR comparison to add in the same session the following:
- Garmin Fenix 6X (FW 8.49 beta) – GPS + Glonass and oHR (left hand)
- Polar Vantage V (FW 5.1.4) – GPS + Glonass + oHR (upper left hand)
- Suunto Spartan Trainer (FW 2.8.32) – GPS + oHR (right hand)
- Polar Beat – aGPS (iPhone XS) + OH1
- Stryd with the Stryd app
| Fenix 6X | Vantage V | Spartan Trainer | Polar Beat/OH1/ iPhone | Stryd(*) | |
| Distance (km) | 6.13 | 6.17 | 6.18 | 6.22 | 6.05 |
| Max HR (bpm) | 179 | 184 | 190 | 184 | NA |
| AVG HR (bpm) | 153 | 152 | 153 | 151 | NA |
| Calories | 541 | 467 | 635 | 468 | NA |
So, regarding distance – which is right, that’s the big question !? Stryd is very consistent and the data there is the “unadjusted” value – but since I use a fixed calibration factor of 101.6 (details here), you might say that the Stryd distance is 6.147km. If you ask Strava, which took the GPS data from my Garmin run, they will suggest a correction of the length to 6.16km.
What I can say is that for sure iPhone is not right, I did this exercise with Polar Beat a while back (last year) and the result was similar, way higher than all the other devices. So, if we consider calibrated Stryd as being the reference, the deviation of each device is reasonable.
| Fenix 6X | Vantage V | Spartan Trainer | Polar Beat/iPhone | |
| Distance Dev | -0.27% | 0.38% | 0.54% | 1.19% |
When we look at the heart rate values, at least at averages, you’d say that they are also close and there are not difference. But, looking at the evolution in the charts, things are not exactly like that. For HR, I’ll keep the OH1 as being the reference (it could have been the H10, but OH1 works just fine). I used for comparison https://quantified-self.io/ (kudos Dimitrios Kanellopoulos).
Because it’s difficult to align starts of all activities, the HR data may have an offset give by the fact that the activities didn’t start exactly at the same moment (I had to start 5 sessions, 2 on mobile and 3 on the watches), so some data shift is inevitable.
But, what you can see is that Vantage V starts more vigorously, Spartan Trainer has a drop initially and then picks up and that Fenix 6X has bump of 16 bpm after 5 mins of activity.
In the run, I inserted on purpose two more intense intervals, where I wanted to see how the oHR is coping with the higher intensity. Vantage V and Spartan Trainer where ok when accommodating the raise of HR, even the slow down – Fenix 6X stayed up for a period of time.
So, the above analysis proves what was being told regularly – that for high intensity sessions you’re better with an external sensor ( a chest strap like Polar H7/H9/H10 or Garmin HRM or Wahoo or even Polar OH1) and you can’t be certain with only the oHR of your watch. I’d say that with the (more) recent sensors, if the device is light enough you might have some chance to get it closer to chest strap.
In terms of GPS track, high level they look decent, you won’t see big deviations.
When you look close, especially at the corners, you may see some differences
So, if your target is to have the most “beautiful” lines, I’d go with Vantage V and Spartan. The Fenix 6X is not bad either, but it cuts some corners. Since I usually have the Stryd with me for measuring distance/pace, the GPS track is only something that gives me some guidance where I was and unless it’s completely awful, I won’t be that concerned. But that’s only me.
In this case, for me the conclusions are:
- Fenix 6X goes for any running sessions only with external HR sensor (OH1 or chest strap)
- if I only want to wear the watch when running, the preferred options would be Polar Vantage V and Garmin 945 (because it’s light)
- Spartan Trainer is a nice option – too bad that Suunto doesn’t have the web app anymore to look over your data and you have to push the info into other platforms (but anyway, that’s something that a lot of people still do)
That’s it folks … train and stay safe!
Liviu Nastasa 
Dear Liviu, nice review and data, i am a fenix 5 plus user and iam thinking about boumce to the new 6pro. My doubt is related the ohr from both devices as 5 plus seems quite accurate and for the 6 there are so many complains about its accuracy. Do you plan make a review comparing both ohr accuracy ? As i understand you have also the f5x.
Thanks
I no longer have the Fenix 5X, but my experience so far with 6X is good at least for daily wear (24/7). The same applies for 5X or 5X plus. For sport activities, I would recommend a HR strap (either a chest or a arm one) as they are better at detecting the higher HR in HIIT sessions. Both 5X and 6X are heavy watches and they are prone to excessive wobbling, regardless of how well you tighten the strap or the watch.