Team Suunto vs Team Garmin – The Roundabout-of-GPS-Doom Duel – GPS/Cycling Accuracy Test

After a Half-Iron distance race at the weekend, today was still a recovery day. 10k on a bike seemed sensible enough as did the thought of combining that into a GPS test. The cunning plan was to circle the Roundabout-of-GPS-Doom.

Perhaps a faster-moving me might give rise to different GPS results than previous running-based tests?

The Teams:

  1. Team Garmin
    1. Forerunner 920XT
    2. Edge 820
  2. Team Suunto
    1. SPARTAN Sport
    2. SPARTAN Ultra

Match Conditions

  1. All latest firmware as of 27Sep2016.
  2. Wrist-worn except 820 (this might favour the 820 very slightly)
  3. Cloudy, daylight, light wind, 17 celcius. No tree cover, no buildings.
  4. 15 minutes of GPS recording in a warmup ride.

Here is a clickable image of the main talking point of the match.



  • Distance – all were in the range 9.69-9.74 and I stopped the watches whilst moving which could easily account for 20m. They’re basically the same.
  • Power – the two Garmins tracked the average as 200w from the same source +/- 1.2w from a ROTOR 3D+ InPower single sided crank.
  • Speed – was near-identical, although the 820 had a minor wobbly at 7:30 minutes. A yellow card offence.
  • Elevation – The 820 failed at elevation (referee wasn’t looking, otherwise a second yellow) – A surprise as in training at the weekend over 90km, the 820 and 920 both performed near identically. For the other Garmin and 2 Suuntos, I could not tell which was correct.
  • HR – both Suunto’s simultaneously lost the HR track from the 4iiii Viiiiva. that is almost certainly BTLE a transmission issue from the dual-band 4iiii HRM. However the ULTRA didn’t pick up the HR again when it came back on track. That is a yellow card offence.
  • GPS Tracking (Visible judging of the above map) – all 4 tracked the ‘pattern’. The two Garmins were off the track a few metres skewed to the East. SPARTAN Sport was ‘just’ the most accurate looking.




In the GPS game there are no points won or lost for power/speed/elevation performances. So all that mattered was the GPS track in what, I have to say, were UNchallenging and near-perfect conditions. The first image shown above was indicative of the performance of the entire route. They were all very good boys and girls and performed well. At any and all points they were probably no more than 5m out from each other. THAT is supposedly the accuracy of a GPS signal or thereabouts AFAIK.

A DRAW, in normal time.

For the penalty shootout I would say that the Team Suunto just edged it (pun intended) but only because of the Garmin’s Easterly skew. HOWEVER, based on this test, I would have no problems buying any of them on GPS accuracy grounds. Other recent test with these devices are <here>, <here> and <here>. My tests are not scientific (look at when he gets a SPARTAN)

Edge 820 – The speed issuette and the elevation track were a little concerning. Personally  I’m interested in neither bike speed nor, usually, elevation. But some of you are. Genuinely, over the 90km at the weekend both Garmins tracked elevation consistently – although the Edge was consistently lower. That could quite easily be put down to me never bothering to calibrate it.


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Daniel Pindado

to be honest i am rather disappointed how you are handling the whole spartan gps accuracy topic. in your first post about the spartan you wrote that it had razor sharp accuracy. being gps accuracy one of the hottests topics about running watches, this created lot of buzz. weeks later I have realized you deleted this comment. good blogging practices say, you should have added an EDIT comment to the post, in case your opinion changed, maybe stating why your opinion had changed. that is what serious bloggers do, at least. but you just deleted it, so that in will never be found again. as i said before, rather disappointed. difficult to trust anything else you write.

Race Leader

it is still there 🙂 you can find the original in the google caches if you look.

Daniel Pindado

i am refering about
initially you wrote: “GPS accuracy LOOKED RAZOR SHARP” . and you wrote it twice. this has disappeared from the post. you could have added an “EDIT” as you have just done in your comment in this post. but you didnt. you just deleted it. this is a cached version of the website:


Daniel you sound rather bitter and selectively choosing a quote in an article clearly marked as “first impressions”. Did you expect 5K Runner to falsely claim that his results of the 1 track at that time weren’t razor sharp?

I, and I imagine most people, read that mini article as the results of one solitary run and did not go racing out to buy this watch before thorough reveiws were conducted. But this doesn’t sound like your exeperience does it. This watch seems to give variable GPS results based on conditions. Some very accurate in clear conditions, some extremely poor in covered conditions.

I for one hope 5k Runner keeps posting exactly what he sees. Keep up the great work.

Race Leader

thank you!! I’m glad someone said it. to be fair it was the wrong word (this site has about a million of them, a few will be wrong 😉 )

Daniel Pindado

i have seen that you have corrected again the article. and now you are explaining about the razor edge stuff.

that is the way to go,

Race Leader

There will be tests published today v800 vs Spartan vs tomtom vs garmin 235. see for yourselves which is best. much harder test with fit files (or see latest post and link to the files on the net already there). Some might even comment that sections are razor sharp 😉

Daniel Pindado

after realizing that GPS was not razor edge, he could have let the comment stay and add an EDIT tag below, explaining exactly what you mean: it was only first track, etc.. this is what most folks do.And he does add EDIT tags very often. and these kind of EDIT tag are good for the credibility of the blogger.
i also do read his site and i do like it.
Deleting a comment without advice, is not something i find OK in a blog. not good for own credibility.


It was clearly a first impression run. Your issue initially seems to be the comment that this first run was “razor sharp”, and now your issue is that it was edited out.

So which is it?