Times and distances vary from friends who run along side me

mariat
mariat Registered Users Posts: 3
Apprentice Seeker
edited January 24 in TomTom Sports
I run as part of a running group and since using my tomtom spark 3 my times are slower and my distance less. I have run exactly the same speed and distance as my group members but when i look mine always fall short and when I upload them to strava even worse is quiet frustrating to say the least any help to correct this gratefully apreciated

Comments

  • tfarabaugh
    tfarabaugh Posts: 16,943
    Superuser
    There are a few factors at play here. Time should be the same unless you have auto pause turned on (or if you have it off and they have it on). Without auto pause it is just measuring from when you press start to when you press stop. If you are referring to pace, not time, that is influenced by the same thing that distance is. A variance in distance between devices is totally normal. The nature of consumer grade GPS is that each data point collected is only accurate to within 15m-30m of your actual location. We give it a lot more credit than it deserves, it is not exact, it is an estimate. The watch collects the data points and then the website tries to figure out a route using them (considering that some points may overlap or duplicate) and a corresponding speed and distance. The watch then smooths the data to come up with the most reasonable route taken according to the algorithm it is programmed with. Every watch, even two of the same model, will come up with different distances and speeds, as they are collecting different GPS data.

    As to Strava, every site or platform has a different way of handling the data it imports. Some take the data as is while others reprocess it and apply their own calculations and smoothing algorithms to it. This second instance will result in discrepancies between the watch and the site, causing issues like you are seeing (which is what Strava does).

    There is nothing you can do to fix this, it is the nature of the device and the platform you are using. I hope this helps answer your question. If so, please mark it as a solution so others can look for it if they have the same question.
  • mariat
    mariat Registered Users Posts: 3
    Apprentice Seeker
    I do take into account auto pause etc as I used to use only Strava until it stopped picking gps up and alowed for some differences but there is quite a bit of diffence I have done extra laps and still fall shorter on distance
  • tfarabaugh
    tfarabaugh Posts: 16,943
    Superuser
    mariat wrote:
    I do take into account auto pause etc as I used to use only Strava until it stopped picking gps up and alowed for some differences but there is quite a bit of diffence I have done extra laps and still fall shorter on distance
    Are you running on a track? If so, that is going to exacerbate the problem. GPS does not do well on tracks; the constant turning throws off the readings as it cuts off the corners. You are also making the assumption that your watch is wrong and everyone else's is right. You can actually take the tcx or gpx file and upload it into numerous websites which will recalculate the distance. do this with everyone's files and you may be surprised to find out you are all wrong. And that is the point, every watch is wrong, it is juts how they match our expectations. You may just have to accept that each device is what it is and you still put in the same effort regardless of distance, which is just one metric (and a minor one at that) and move on.
  • mariat
    mariat Registered Users Posts: 3
    Apprentice Seeker
    Wooo tad touchy just looking for advice!!!
  • tfarabaugh
    tfarabaugh Posts: 16,943
    Superuser
    mariat wrote:
    Wooo tad touchy just looking for advice!!!
    I was not being touchy, just explaining the inherent issues with the watch and GPS technology in general.