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Epix 2 GPS is horrible

JoseR
over 2 years ago

I think it's time to admit that I'm deeply disappointed about GPS accuracy of my Epix. Sure, the track (multiband) is spot on and beautiful but total distance is just a disaster. I know that accuracy is never 100% but after 6 months or so and several races the watch is barely usable, the distance is just way off. For pacing purposes my old FR945 was much better even with an ugly track. I don't know... maybe it's just my watch but I'm not happy anymore with this watch. Did anyone have the same experience?

  • 0 over 2 years ago in reply to JoseR

    Might be unrelated (and you may know about the feature) but you can try playing with the 3D settings for your activity type. I recently discovered it myself

    Quoted from page 2 of that thread:

    I always get a chuckle when people don't use the feature and they're running in the hills with a lot of elevation changes and they complain that the distance is off.  GPS measures distance by line of sight from GPS points recorded.  A 100 meter straight line with GPS doesn't mean 100 meters travel if the start and end point has a depression in between. 

  • 0 over 2 years ago in reply to Josh
    Josh said:
    Do you recommend turning on Every Second Data Recording for all of your activities? 

    Yes.

  • 0 over 2 years ago

    I had a similar problem. I'm using a HRM-Pro Plus and a Stryd Footpod. The sensor configuration was wrong. The Epix calculated the distance based on the Footpod and not based on the GPS-Data.
    You can find more information here.

  • 0 over 2 years ago

    would be very careful assuming that race distances are correct per the race organizer as sometimes small changes they make can mean the actual distance isn't as reported, as Camille Herron found when her 100 mile world record she set in February was disallowed as course distance was 700m too short due to a course change. https://www.washingtonpost.com/wellness/2022/11/16/camille-herron-100-mile-record-error/

    Per the article it was interesting to note that this isn't the first time issues like this have occurred.

    Also note that the course distance is based on shortest possible route, so when people actually run it, its very likely that you will always show a higher distance to not always running on the shortest side of the route.

    So suspect that your GPS isn't horrible and is probably very accurate based on the actual distance you ran based on the route you took (i.e. sides of the course, where you made your turns, where you clipped apex etc).

  • 0 over 2 years ago in reply to Josh
    Josh said:
    I always get a chuckle when people don't use the feature and they're running in the hills with a lot of elevation changes and they complain that the distance is off.  GPS measures distance by line of sight from GPS points recorded.  A 100 meter straight line with GPS doesn't mean 100 meters travel if the start and end point has a depression in between.

    Unless you trail run extremely steep slopes, or stair scales, I'd rather recommend keeping the 3D option off, since it is a common source of distance and speed errors. The elevation from the barometric altimeter used for the calculation is quite often very sensitive to strong peeks or drops of tens of meters, for example due to wind gusts, or moisture/dirt entering the pressure sensor port, and it is also a subject of more steady, though significant elevation changes due to temperature and atmospheric pressure changes.

    All of that will result in deviations of the 3D distance and pace, and often those differences may be quite important.

    In contrary, under normal conditions, the impact of climbing and descending, has a negligible effect on the pace and distance, so keeping the 3D option off is much safer, and more accurate, than having it on. Take for example a slope with the grade of 10% (that's already a rather hard climb). It means 10m elevation diference on 100m distance. Using the 3D option, the 100m distance would be corrected by 100-sqrt(100^2+10^2) = 0.498 m - that's pretty negligible difference (0.5%), and on my mind absolutely not the worth of risking that the altimeter records a pressure change resulting in a much bigger correction.

  • 0 over 2 years ago in reply to jaamgans

    I totally agree. My perception of "horrible" GPS was based in the total distance comparation with my old FR935 and FR945. Both of them had closer distances to the official 26.2 for a marathon (26.32 vs. 26.55, for this, I'm considering NYC marathon is accurate). It turns out that I think the Epix2 distance is closer to the distance I actually run. The other watches were cutting some corners and  therefore "cheating", so it wasn't a real accuracy.