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Running Distance / Pace calculation is flawed / needs rework

Hello, A while ago, I reported that my Fenix 8 watch under-reports distance by a large (from a training athlete's perspective) amount, resulting in wrong running pace reported. 

This affects someone who is actively training both during running - pace is under reported, as well as post training and in planning. 

On today's 7km run - as reported by the Fenix 8 - the recorded GPS track distance was actually ~7.55km. So the distance is actually being recorded correctly, but the watch applies (as I've learned in the previous post) some corrections / calculations based on stride length and cadence, to figure out distance, and purportedly ignores the GPS track distance. 

Garmin has also recently removed the ability for users to specify stride length manually - so you are stuck with what the watch "thinks" is your stride lenght based on accelerometer data, etc. 

Now - to me as a runner who is actually training - distance is distance, based on map data and gps track length - not a calculation you are stuck with and have no control over. In today's run as reported by my F8 my running pace was 5:05min/km over a distance of 7.02km. But based on the recorded GPS track and MAP data - I had a running pace of 4:44min/km over 7.55km. These are two VERY DIFFERENT running paces / running zones, pertaining to DIFFERENT TYPES OF RUNS for DIFFERENT END GOALS within the training block. They cannot be used interchangeably!

Which one should I - an actively training runner - take as correct & accurate when running and planning my training block, with my top-of-the-line flagship sports watch

Has anyone ever found a fix or workaround to have the ACTUAL track distance/map distance reported on their activities instead of useless calculations? 

Also a note to Garmin - shouldn't you put a better use to your "athlete intelligence" technology - to analyze post-activity data and apply corrections based on hard facts (map topographic and survey data for distance / elevation) and IMPROVE such a CORE FEATURE of your devices like Running, instead of using it for shiny "golden badges" and an "intelligent insight" that tells me that my recent stress of 23 is lower than my average past stress of 25??? Slight smileSlight smileSlight smile Current features like HILL SCORE and ENDURANCE score are utterly useless (algorithms are wonky and elevation data gets skewed by the slightest change in ambient pressure or temperature)

Why are athletes penalized when this is a "SPORTS WATCH" and we are getting newer and fancier "smartwatch", "wellness" and "social" features instead of focusing on having a ROBUST and ACCURATE training experience on a thousand dollar Flagship sports watch??!! 

  • Distance/pace as reported by the watch 

    Track length

    Corrected data

  • While not as extreme as yours, and I am no where near the training level as you, I have seen this. I routinely need to run 3.25 Miles to get credited with a 5K. Though I have noted this is not as extreme in the winter. Could the cause be not having direct line of sight to GPS because of the tree canopy blocking it? I routinely run on a 1 mile loop. In the winter, 1 mile = 1 mile, but in the summer 1 mile = 0.95 miles. If it is the trees interfering, the watch is missing GPS points and is rounding the track shorter.

  • Do you use an external HRM like HRM PRO ? 

  • For reference, I have been using an HRM Pro+, my HRM600 only arrived today.

  • I wonder if you change your gait cycle in the winter? For example do you have a longer / shorter stride die to snow, or maybe shorten your steps for more stability? It could all play into the result, as the watch will mix running dynamics data into the end result. 

  • I use my hrm pro+ only when doing certain types of workouts (like sprints / anaerobic work) where the OHR is slow to pick up hr increases /decreases. But I always keep it on HR only, I keep pace/distance disabled on the HRM, as the pace is 0:25-0:35 min/km faster than in reality, and the reported distance is actually longer than the GPS track. 

  • Today's run, 

    GPS track length: 10.3 km (Clear sky, no tall buildings or trees, healthy GPS).
    Distance reported by watch after activity end: 9.68 km.

    I checked the stride length average: 1.05m. Average cadence: 179 spm. 1.05x179x51.5 min = 9679 meters. So it's clear that the watch is set to "estimate" running distance using the above calculation instead of relying on a healthy and accurate GPS track of 10.3 km, resulting in an error of 621 meters and a difference in pace of 00:20/km (5:00/km [gps] vs 5:20/km [estimation]).

    So I deduct that the stride length is under reported, resulting in a lower estimated distance. The effects of this issue cascades into other metrics that a runner needs to be accurate - especially running pace. 

    Garmin: Could you please consider either offering the option to have pace reported according to GPS or an average between GPS and stride length? It's clear that the current solution is not the most accurate. 

  • I'm not disputing your findings, but my 8 51mm amoled is a huge improvement over my 6xPro and 5x+.  My training isn't as extensive, but I have noticed that compared to my 6xPro, it is significantly more accurate when it comes to distance.  I mostly run trails with switchbacks.  the 6xPro would consistently under-report by between 2-4%.  I started using a Stryd pod to compensate and the Stryd is very accurate.  However, my 8 is spot-on with the stryd.  I've been very impressed with my distance accuracy.  With that said, I haven't evaluated the pace statistics to make an assessment on it's accuracy.

  • Have you checked GPS track length vs the distance reported by the watch, without any 3rd party sensors? 

    Yes, the 8 is definitely an improved device compared to the likes of Fenix 5 (a 7 year old watch) and the Fenix 6 which is one of the most inaccurate distance-wise according to most reviewers (check DC rainmaker's comparisons) 

  • This is interesting, but where do you see this Track length information? Is that in Garmin Connect, I can't find it?