Had a discussion today after XC regarding Garmins, everyones calculated todays race as under. Race organisers confirmed the course was measured 4.9km. I read and found myself where there are hills garmins cannot calculate this as they dont measure footsteps they measure via satellite, hence they can not detect hills. Hers the proof I copied from a forum discussion HIRSCH92 10-23-2009, 09:14 AM Ive thought long and hard about whether distance calculations include elevation. It seems to me that my Forerunner 405 cannot possibly be figuring elevation into its distance calculations. On other forums, runners complain that run organizers inaccurately measure their courses because the purported distance is greater than the distance as measured by their GPS (by much more than insignificant amounts). On most of these, elevation is a factor. Consider this: if we run up a hill, we run up its hypotenuse, not its base. If the GPS only measures surface distance without considering the elevation increase, it will miscalculate our pace, speed and distance. Visualize your run as a 5,12, 13 right triangle. If the base distance is 120m and the elevation gain is 50m, youre really running 130m up the hypotenuse. You might be asking what the big deal is because 10m doesnt amount to a hill of beans. If you run in an area with hills or mountains, it matters. Consider that Pythagoras doesnt discriminate between uphills and down hills. As you come down the other side of the hill, youre subject to the same phenomenon. Any course with rolling hills or a steep gradient would be off if it didnt take elevation changes into account. It seems to me that the GPS cannot take elevation into account because the machine is so wildly off in its elevation calculations. Ive had out and back runs where there was as much as a 100 ft difference in the the same section of the run. If it considered these fluctuations in distance calculations, the outcome would be way off. Also, Ive noticed that my downhill paces are only somewhat faster than my normal pace. Sometimes, when I take it slow, my downhill is actually slower. Something is not right there. Does anyone know if this issue has been covered by the techs? Sorry for the long post, but I wanted to get it right and make my HS math teachers proud.
Posted on: Sat, 27 Sep 2014 17:38:01 +0000
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