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Which is correct? Your Garmin or the RD? (Read 324 times)


On On

    I was just reading another thread somewhere else and it had several comments by people that run races on certified courses while wearing garmins.  If they finish the race and their personal garmin does not state they ran the race distance they will go out and run more until their garmin says they ran the correct distance.

     

    My question is, which is correct?  The certified course or your garmin?

     

    Second question, you run the same 10 mile race with 3 friends and you all wear a garmin.  At the end of the 10 mile certified course you have 9.8 miles, friend 1 has 9.6, friend 2 has 10.2 and friend 3 has 10.4.   Who is correct?  Do you and friend 1 have to go run further to make up the difference?

      The RD/certified distance is correct.

       

      If a course is short or long, that's another story.  I almost always assume Garmin error, but I am talking about the outlying situations like, "Oh, yeah, one of the volunteers put the finish chute in the wrong place."

       

      On trail races, especially, I consider my Garmin to be at best approximate.

      "When a person trains once, nothing happens. When a person forces himself to do a thing a hundred or a thousand times, then he certainly has developed in more ways than physical. Is it raining? That doesn't matter. Am I tired? That doesn't matter, either. Then willpower will be no problem." 
      Emil Zatopek

        It's somewhere in the middle. The certified course is measured assuming the tightest corners which runners are not often following as exactly. I run the course and if it's a bit off, I don't stress it. I don't go run extra.

        "Don't feel like running today...suck it up and run ...you're an athlete." (John Stanton, founder & owner of The Running Room)

         

        Three half marathons later, I got a number. Half Fanatic #9292. :)


        Interval Junkie --Nobby

          Trick question: everyone knows the course was certified with a Garmin in the first place.

          2014 Goals:  sub-3 Marathon 

          Current Status 11/10: Back to building up miles.  Junk feels mostly okay.  Kinda.


          Petco Run/Walk/Wag 5k

            As has been said a certified course is measured at the shortest distance or tangent points on curves - something most runners are actually able to run. This can be demonstrated by thinking about concentric circles, the circumference of the inside circle, e.g. certified distance is less than the circumference of the outside circle. By how much depends on how much larger the diameter of the outside circle is and how long someone runs along that line. In long races on wide curvy streets/trails this can be significantly longer than shortest certified distance.

             

            Garmin's are mechanical/electronic devices with built in tolerances otherwise known as "errors" and most often will show a run longer than race distance - if it hasn't lost lock during the run. Running amongst tall buildings, or under cover of dense tree cover can cause Garmin's to lose lock and who knows what they are measuring at that point.

            bob e v
            2014 goals: keep on running! Is there anything more than that?

            Complete the last 3 races in the Austin Distance Challenge, Rogue 30k, 3M Half, Austin Full

            Break the 1000 mi barrier!

            History: blessed heart attack 3/15/2008; c25k july 2008 first 5k 10/26/2008 on 62nd birthday.


            I'm back!

              I was just reading another thread somewhere else and it had several comments by people that run races on certified courses while wearing garmins.  If they finish the race and their personal garmin does not state they ran the race distance they will go out and run more until their garmin says they ran the correct distance.

               

              Well geez, I thought I would leave that FB thread from hell and come here, for a breath of fresh air...


              Feeling the growl again

                   Who is correct?  Do you and friend 1 have to go run further to make up the difference?

                 

                Though I suspect you ask the questions tongue-in-cheek as you have a reputation for organizing very well-run events....

                 

                Neither.  As your example illustrates, it is easy to demonstrate to people that GPS is not infallibly accurate by having a group run together and then show that there are differences between their GPS units that cannot be explained away since they ran together.

                 

                The certified course is not accurate either, by design.  An accurately certified course will always be a bit long.

                "If you want to be a bad a$s, then do what a bad a$s does.  There's your pep talk for today.  Go Run." -- Slo_Hand

                 


                I'm back!

                  As has been said a certified course is measured at the shortest distance or tangent points on curves - something most runners are actually able to run. 

                   

                  Unless it's Newport OR, a notoriously fast course, where Garmins would often read 25.8ish. When the course was recertified, surprise, it  was a quarter mile short. There went a lot of PRs.

                    Or someone put a turn signal/cones in the wrong place.  Good for about .06 difference below.

                     

                    Certified course

                     

                    Actual race

                     

                    MTA fixed the links.  Also would not mind if Garmin measures a bit long, but if its short, assume a missed turn or wrong course ran.

                    MJ5


                    Chief Unicorn Officer

                      If my Garmin is within .05 or so for a shorter race like a 5K (say, 3.07), I accept the course as accurate. Especially courses with lots of turns, or pinpoint turns, sometimes the Garmin is thrown off. Plus my understanding of GPS technology is that it plots points as it is measuring and just connects those points with straight lines to measure the distance. That makes me a little skeptical of exact Garmin measurements.

                      Mile 5:49 - 5K 19:58 - 10K 43:06 - HM 1:36:54


                      HobbyJogger & HobbyRacer

                        It's best to measure with your car, because the tires keep 100% contact with the road, making for a more smooth, reliable measurement than a runner bouncing up and down.

                        It's a 5k. It hurt like hell...then I tried to pick it up. The end.


                        I'm back!

                          If my Garmin is within .05 or so for a shorter race like a 5K (say, 3.07), I accept the course as accurate. 

                           

                          I ran a 3.18-by-Garmin 5K last weekend; missed my PR by 4 seconds. I'm sure the course is correct; I was just bummed because I kept my Garmin average pace 7 seconds under what I needed; typically 3-5 is safe for Garmin error. Oh well.

                           

                          Plus my understanding of GPS technology is that it plots points as it is measuring and just connects those points with straight lines to measure the distance. That makes me a little skeptical of exact Garmin measurements.

                           

                          That's one issue. Another is that the individual points are noisy; they can be 20-30 feet off, under *good* conditions. That said, the unit does do some smoothing to try to correct for both of these. But it's still based on underlying noisy, sparse data.

                            Uncertainty is woven into the fabric of the universe

                            Runners run.


                            just a simple cat

                              if it is NewJersey, the the Race Director is always correct!

                               

                              Running is stupid

                                Uncertainty is woven into the fabric of the universe

                                 

                                Noooooooo!!!! Say it aint so!!!!

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