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Mountain Biking altitude measurement

Oren
over 6 years ago

Hi all,

After more than a year with the Vivoactive 3 as my watch while riding mountain bikes, I'm one of many owners who are very frustrated with the watch altitude metering.

Finishing a round bike ride I usually am ~70-100m lower than my starting point, missing ~40% of the accumulated climb.

I'm considering buying later this week the 945 and hoping I can get a confirmation, here, that this is not an issue to be worried about.

Also, I do wonder, following some looking into this forum what are the main "illnesses" related to this watch considering "smart-watch" usage and mountain biking as well of course.

Thanks!

  • Former Member
    0 Former Member over 6 years ago

    Unlike your VA3, you'll be able to calibrate both your altimeter and barometer with the 945.  One of the nice features is calibrating the elevation using DEM.  It use elevation based off geographical surveys, like the 235 does to track elevation because it doesn't have a barometer.  I rarely MTB ride, but I run and cycle here in the Cascade Mountain foothills without any issue. My start/finish point are within a couple of feet of each other.  My wife has the VA3 and the two are like comparing night and day with the elevation readings.  I think you'd be very happy with the results should you decided to go with the 945.

  • 0 over 6 years ago in reply to Former Member

    Thanks a lot! 

    Yet, you made me think I should reconsider the 245 cheaper watch to fulfill my needs with half the price... 

  • 0 over 6 years ago in reply to Oren

    The 245 doesn’t have a barometer sensor built in, so the elevation from GPS is ‘noisy’ as the maths behind GNSS vertical position location means it’s precision is approx 5 times less than horizontal (some basic info from Garmin here https://support.garmin.com/en-GB/?faq=QPc5x3ZFUv1QyoxITW2vZ6 ). Elevation from a barometer is very precise (can show very small relative changes) but can be inaccurate if not regularly calibrated (accuracy being the right relative position); this is due to changes in barometric pressure from weather, temperature and other localised effects.  Happily the 945 (vs 935) can now continuously calibrate its barometric elevation using the Digital Elevation Mapping loaded on to the watch; so you should get the best of both worlds (precision and accuracy).

    I can’t find any Garmin support pages for the 945 about elevation continuous calibration, but that doesn’t surprise me as it’s a fitness division watch rather than outdoor division. Anyway, as the MARQ is the same as the 945 in fancy clothes, the following support page is relevant https://support.garmin.com/en-GB/?faq=Gl2juBbnSc1NJ36gkA9hS8&productID=633625&searchQuery=Elevation%20continuous%20calibration&tab=topics#related

    Best description of precision vs accuracy is the chart below. GPS elevation is accurate but imprecise (bottom left) and barometric elevation should be accurate and precise if calibrated (bottom right).

  • 0 over 6 years ago in reply to Crispin_Ellisdon

    Wow - answered all my questions (and future ones) at once Slight smile

    MANY THANKS!