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What's your biggest Garmin vs. RA map discrepancy? (Read 527 times)


Needs more cowbell!

    I rode 3 loops of a new trail yesterday.  Another friend also was riding with a Garmin that kept losing satellite reception in ravines and switchbacks and under heavy tree cover.  Mine was likely losing, too, but I long ago shut off the infernal auto-pause beep, so I am no longer aware when this happens.

     

    So the Garmin recorded 10.91 miles, but when I uploaded to RA it reads 12.43 miles overlayed on the actual map with RA's elevation correction (I have found Garmin's barometric altimeter to make really odd elevation profiles with flat, "plateau'd" sort of tops, so switched back to letting RA do the work.  I suspect RA/Google are more accurate).

    Kirsten - aka "Auntie Kirsten"

    '14 Goals:

    • 2 olympic distance duathlons -- 6 days apart -- PR at least 1

    • 130#s (and stay there, gotdammit!)

      I'll get a little bit of this when starting a run in downtown Boston before getting a solid satalite lock but fortunately I haven't noticed it running or biking in the woods.

       

      On my garmin the lost reception alert is different from the auto pause alert. Perhaps the beep is the same but the display clearly tells me what is going on. Are you sure your autopause is fully turned off or just the beep is? It took me a few tries before I was able to fully turn it off on mine. I thought I had it figured out but was doing it wrong for a while.

       

      I can't think of a worse activity for autopause than mountain biking. Riding under auto pause speed through technical stuff, up hills, or doing the dreaded hike-a-bike won't be measured by your garmin. RA's map will connect the dots in a straight line, which might also not be correct. That means your rides could be even longer than the RA map claims!

       

      As an extreme illustration of this, here's a recent run I did. I ran a couple miles, paused my garmin, then jumped on the train for a few miles, and finally ran a couple more miles home. Since I paused my garmin it counted only 5.05 miles of running while the RA map figured it as 9.57 of distance traveled by connecting the pause and unpause points in a straight line. If actually ran between the points using roads it would have been easily over 10 miles.


      Needs more cowbell!

        Hmmm...I always have had the autopause set to only pause if I drop <1mph (I don't use autopause at all for running, just biking, since there's a fair amount of starting and stopping for traffic and waiting to regroup, etc.).  It always works reasonably well on roads, though I still tend to show about .5-1 mile shorter than other people on a 30 miler with good satellite reception.

         

        I've been really surprised by how off the Garmin is on heavily wooded trails, though, especially if there's significant hills and ravines.  Hearing my friend's unit beep every time it paused and unpaused--even when she was rolling--was pretty startling.  Though maybe she has hers set to pause at a higher speed, which could make a difference going really slowly around a tight turn or up an especially steep spot.  I wonder if turning that off would make any difference in the distance #s.  If it's mostly an issue of losing satellite I would think it's going to be off, regardless.

        Kirsten - aka "Auntie Kirsten"

        '14 Goals:

        • 2 olympic distance duathlons -- 6 days apart -- PR at least 1

        • 130#s (and stay there, gotdammit!)

          I'd try turning it off completely. Now that I recall, someone else told me he noticed that auto pause always seemed to resume in a different position for him and had to stop using it due to that. I can see how this would result in the same problem you have experienced.

           

          On my road bikes I use the ant speed sensor and auto pause. Since it's wheel measured distance I don't see issues.

            I can't think of a worse activity for autopause than mountain biking.

             

            Especially since pace is totally meaningless on most MTB rides.

             

            Wouldn't a $30 wireless bike computer be a way better tool for this job anyway? Is the ant speed sensor the same thing but works with your Garmin? That would make sense.

            Runners run.


            Needs more cowbell!

              Yeah, this would likely be the best solution. I use the Garmin speed/cadence/distance sensor on my road bike in the Winter to track my workouts on the trainer. I'll miss the rough maps in the woods, but not as much as I miss those hard-earned miles in my log. Tongue

              Kirsten - aka "Auntie Kirsten"

              '14 Goals:

              • 2 olympic distance duathlons -- 6 days apart -- PR at least 1

              • 130#s (and stay there, gotdammit!)


              Needs more cowbell!

                Interesting...I just happened to read a thread on a mtb forum re: different Garmin Edge models for trail riding.  Apparently the 500 (which is what I use on my bikes) is intended more for road riding (ie more lineal tracks) and samples less.  The $$ Edge 800 generally works far better off-road (and it seems that Garmin even categorizes the 500 as a roadie unit and the 800 as an off-road computer) but still has a bunch of bells and whistles that I never would have paid for -- touch screen sounds like something I would bust and I don't need pre-loaded navigation or maps.  I don't really LOOK at my Garmin while riding and especially not while riding in the woods...it's all I can do to keep from wrapping myself around trees, as is.

                 

                Kind of odd that they would have set up the simpler unit more for road riding and the more complex and sensitive one for off-road.

                Kirsten - aka "Auntie Kirsten"

                '14 Goals:

                • 2 olympic distance duathlons -- 6 days apart -- PR at least 1

                • 130#s (and stay there, gotdammit!)