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310xt and Foot pod vs GPS - distance question

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  • 310xt and Foot pod vs GPS - distance question

    Under the foot pod settings, you can choose between GPS or the foot pod for speed. Does anybody know what setting the speed mode to foot pod is supposed to do? I tried it out today and it looks like the only thing that setting affects is the real time pace. The lap pace and distance seemed to still be based on the GPS. My calibration was off so my pace was showing ~7:30 while my lap pace showed ~8:00. (yes I had just recently pressed the lap button and kept a pretty constant pace and it took me 8 minutes to run a known mile). I changed the speed mode back and forth a couple times during a run. Looking at my downloaded file, the graph looked nearly identical across the whole run, even the miles where I had set it to use the foot pod for speed. So clearly it recorded distance based on the GPS.

    So how bad does the GPS signal have to be before it uses the foot pod for distance? Is there anyway to force it to use the foot pod for distance but still record GPS coordinate information?

    I read that the 305 can be easily switch between indoor and outdoor by holding the mode button. On the 310, that brings up the sport list. I assume indoor mode turns off the GPS, correct?

  • #2
    I have uncovered another interesting thing regarding speed, distance, and the foot pod. The .tcx files record a "speed" field if you are using a foot pod. This seems to be affected by the GPS vs foot pod speed mode settings. The recorded "distance" seems to always be based on GPS. Viewing my run where I switched back and forth in Training Center, the "speed" or "pace" is quite smooth where I had it set to use foot pod and is quite jagged where I told it to use the GPS. When I load the same file in SportTracks, it seems to calculate the speed based purely on the distance. In this case, the entire graph is jagged.

    The average pace and distance still seem to be based on the GPS speed/distance. Only the line you see in the Training Center graph seems to be based on the speed mode. I assume this is not the case if you turn off the GPS for running indoors but I haven't tried that.


    • #3
      The speed source setting only affects the instantaneous speed/pace reading as you have observed. There is not a way to force the unit to use distance from the footpod and still record GPS position. The distance recording will automatically switch to the footpod if the unit loses its GPS fix.


      • #4
        So just to clear this up....

        When cycling with the cadence sensor on it gets speed and cadence from this sensor and not from GPS? What about distance? Is this still from the sensor when cycling?

        And when running, with a footpod, is distance and speed calculated by the footpod or by GPS?

        What about when transfering from one or the other? ie. jumping off the bike with the cadence sensor and into some shoes with the footpod on it?


        • #5
          I can only respond to the second question. If you have gps on, distance will come from gps as long as there is a gps signal. You can have instant pace come either from gps or footpod depending on how you have it set in your preferences.