Running Accuracy

[CJL1412]

Hi - I have been having huge with my ionic not tracking my runs correctly. Being around 500m behind on distance compared to the course or other trackers. Fitbit are replacing it but now I am concerned that my confidence is lost. Do other ionic users get accurate run results - please let me know. Also do you use automatic stride or manual - thank you - Caroline 

[Julia_G]

Hi, @CJL1412, I am pretty confident that my Ionic is accurate on distance as long as I track a run using GPS.  I think if you rely on stride x steps it will always be somewhat off, as your stride will inevitably vary depending on the terrain on other conditions.

Welcome to the forums!

[CJL1412]

How do you track just using gps. I ran with the ionic tonight and a Tom Tom and the ionic calculated 5km in 37 mins and the Tom Tom 34.45 - so my ionic was out by 400m

5k is 5k

Sent from my iPhone 😊

[bmw54]

@CJL1412

If you dare, read (or browse through) Ionic GPS Inaccuracies

In the course of that topic, which started soon after Ionic started delivering, we've spent months determining that the ionic measures distance by (Steps * Stride Length). Anyone who expects accuracy from their tracker has pretty much given up on the Ionic. That is, of course, unless your stride lenght is expressed accurately in your personal settings, and you rarely change pace, and you don't run faster on race day.

It doesn't appear that there's any way you can force Ionic to default to pure GPS for pace and distance (we've repeatedly asked for this capability) unless you use the Bike app; for all I know they settled on this design because Ionic has such difficulty maintaining GPS connection for very long. 

BTW: the bike app, though based on GPS shows pace in MPH and 5-mile cues (no less), so it's not that conducive for runners.

Regarding your statement '5k is 5k'.  When I race, Ionic usually tells me that 5K = 2.6 miles.

[jwebb72]

My Ionic is very accurate. Plotted course on mapmyrun at 3.10k, Ionic measured 3.08k. My wife's phone GPS verifies this distance as well. Lots of hills (354 elevation gain), stride length and pace, not constant.

[Sheldoreo]

Yes, my Ionic also seems accurate to me.  An officially measured 10K race showed as 10.09K on my watch.  The extra 0.09km was mostly made up of the distance between starting position and start line.

Also for Parkruns the Ionic measures the same as my old Garmin did, which is good to know.

[Winnie10]

My Ionic doesn't seem to be very accurate.  I did an official 10k on Sunday, so I trust that the route is accurate.  My Ionic tracked it as 9.85k - some may say it's not out by much, but it's enough to be annoying and it doesn't give an accurate view of my pace. I read somewhere else that the Ionic measures distance by calculating steps x stride length rather than GPS, but in my case that doesn't work either.  I do like the style of the Ionic, but am very disappointed with the GPS.

[jwebb72]

@Winnie10

The Ionic seems to be the same as the Blaze or Versa with connected GPS which uses a combination of GPS, steps, and stride length to calculate distance for walk/hike/run. This has been tested in the main GPS inaccuracy thread as well as by myself. Looks like the Ionic shorted it by .15k which is 1.5% off. Within what can be expected with any GPS watch.

[bbarrera]

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@jwebb72 wrote:

Looks like the Ionic shorted it by .15k which is 1.5% off. Within what can be expected with any GPS watch.

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For that particular run...

Its not fair to say "within what can be expected with any GPS watch" because if you track a "run" while driving around in a car you will find the Ionic is almost 100% wrong on distance. Drive 10 miles and you'll see almost 0 miles on Ionic (but the map looks great!).

We aren't talking about GPS accuracy with Ionic, we are talking about:

- step counting accuracy

- GPS accuracy to update stride

- and use of stride * steps to estimate distance, when both steps and stride may not be accurate

[jwebb72]

@bbarrera

I think it's fair to expect 1.5% error or better from any GPS watch, not specifically talking about the Ionic.

That's correct, tracking a run with the Ionic in a car will result in zero distance.

Tracking a run while jogging in place will result in distance, but not stride x steps. The distance is much lower, in the neighborhood of half. One thought is that during a run, the GPS is constantly updating stride length. At what rate it is updating, we haven't figured out yet. We have found that GPS plays a role in distance calculation indirectly. 

[bbarrera]

@jwebb72 yes, in the long thread bmw54 was told by Fitbit that stride estimates are updated periodically by using GPS.

I suspect the reason that jogging in place results in roughly 50% of "stride * steps" is due to GPS reporting small changes in distance, even while not moving. That "GPS jitter" is normal and expected. Then Fitbit feeds that into stride update algorithm, which reduces stride length, resulting in shorter distance (versus static running stride).