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Stryd is not all it's cut out to be...maybe

philipshambrook
over 2 years ago

This morning I ran twice with one watch hooked up to a Stryd and set to Always use for Pace and Distance and another just on GPS. In both cases the Stryd came up with a longer distance. First up was a trail run that we've been running for years so we know it is close to 9km. Stryd returned 9.31 where my GPS Trail Run gave 8.99 and my wife's 945 8.97km. Next up was parkrun. For those who don't know, parkrun is always 5km. Our parkrun has been accurately measured using a calibrated wheel so we know it's 5.04km from the wheel. And every GPS run we've done has been 5km +/-20m or so. This morning Stryd gave 5.24km while the GPS watches gave 5.02 and 5.01 respectively.

This wasn't the first time out with the Stryd. Several runs on a 400m track and a couple of other trails runs should have seen it calibrated by now. I haven't looked over earlier runs as I did want to make sure I had a number of different runs with the Stryd.

Let's see how things progress. I have done a couple of runs on a 400m track but not sure if I had the Stryd set up properly so can't comment on that except to say the watches gave the same distance. However, I now have the Stryd where I want it so can. and will, do some more comparison runs to see how this plays out.

  • 0 over 2 years ago in reply to 5135968

    Nice, I didn't know that I was so close to Strava but then they are probably also short in distance if comparing to odometer.

    Check this comparison from my last long distance run.

    • It was 23.965 km (measured with odometer).
    • The watch measured it to 23.563 km when using Garmin foot pod configured to "Indoor". GPS+GALILEO, data record every second, 3D On and a good soak for the GPS.
    • Sum up of record.enhanced_speed was 23.050 km (used for Speed/Pace in the watch while running and for the graph in Connect)
    • Sum up of gps_metadata.enhanced_speed was 20.430 km (this is really odd...)
    • Own calculation from GPS data (3D excluded) was 23.666 km
    • Own calculation from GPS data (3D included) was 23.724 km

    I also checked distance by cadence and step length and that was 23.219 km.

    So, my GPS distances are about 1% short most of the times. Compared to odometer. But GPS distance with 3D included seems to be the best measurement for me, odometer excluded.

  • 0 over 2 years ago in reply to AndersB

    Why not just use a Garmin running pod then? much cheaper - around £50 - and gives power, oscillation, cadence etc.  Power calculation is all relative anyway and what Stryd say is probably different to Garmin anyway as they use different algorithms

  • 0 over 2 years ago in reply to Markw50

    I think the Garmin foot pod has been discontinued for a while now. 

  • 0 over 2 years ago in reply to Markw50

    Garmin footpod was only accurate when running at a constant pace, if your pace varied on the run the accuracy would reduce sometimes dramatically and therefore pace and distance were out. 

  • 0 over 2 years ago in reply to brian.reiter

    You mean this? Garmin running pod the footpod has been discontinued but NOT the running pod which attaches to your waist band.

  • 0 over 2 years ago in reply to Markw50

    If you want the enhanced running dynamics, R/L balance, cadence, vertical oscillation, stride length and don’t want to use an HRM-Run/Tri/Pro then that is the sweet spot of the RD pod. But the power is iffy at best. 

    The RD pod does nothing for smoothing pace over short distances.

    I have tried the RD pod power but it bounces around quite significantly because it is based on GPS pace as an input. I didn’t find it very useful. For that matter, I don’t really find Stryd power very useful, to be fair. 

    It’s accurate that most of the running dynamics type metrics are the same across Stryd and RD pod — except for R/L balance. But they don’t necessarily agree.

  • 0 over 2 years ago

    Hello all,

    just sharing something I randomly noticed a few days ago. I was driving to a running track for training, and started the activity mode for GPS fix while I was still driving. My stryd was connected, tight on my left shoe (so almost not moving) and it was set for pace & distance - always.
    I would have figured the pace would be close to zero, but it turned out that the pace was the same as the speed I was driving at - so it assume GPS is definitely taken into account in the algorithm to calculate instant pace - even when accelerometer pace is set as priority.
    I may have done something wrong, or this could be normal behaviour - but I don't think so... And I believe it is a quite simple test to reproduce, so if anyone wants to try it - or explain me why this is normal, well... I'm all ears :)

  • 0 over 2 years ago in reply to drkglb
    drkglb said:
    I may have done something wrong, or this could be normal behaviour - but I don't think so... And I believe it is a quite simple test to reproduce, so if anyone wants to try it -

    I can reproduce this - and I don't understand why.

    I just did a bike ride, just 1 mile, with a shoe with a Stryd attached balanced on my handlebars and I recorded the ride as a Run. I confirmed Stryd was connected (footpod icon) and also that Pace and Distance were set to always on.

    My 'run' reported this pace - in my dreams :)

    I would assume that 'pace' is generated by forwards and backwards motion, but according to this, it isn't. Or somehow GPS is still being used, despite the 'always on' settings..

    Very strange and interesting finding!

  • 0 over 2 years ago in reply to 5135968

    Thanks for doing the test on your end and confirm I'm not crazy :)
    I may be wrong - once again - but I think instant pace is using both GPS and accelerometer when they are available. If you disable GPS, I assume that only the accelerometer data will be processed... And with a Stryd sensor it could provide more reactive data. I will try it and report.