Design flaw: Sensor opening in the wrong place. What now?

Following multiple complaints about elevation inaccuracies (during Trail Run and Cycling activities), I compared the Instinct against my trusty Fenix3 HR in a controlled test. Placed both devices in the car, drove for 60km and found very small acceptable differences in Distance and Total Ascent numbers. Conducted several more tests along the same lines, similar results. All good.

When the Instinct is worn on the wrist, however, with the sensor opening positioned so close to the skin, sweat and dirt block the sensor opening leading to errors. My daughter rides with the Instinct and on two occasions, one (worn on the wrist) logged significantly lower total ascent than her peers while on her second ride (worn over compression arm sleeve) logged elevation accurately. 

Thing is, wearing the watch over an arm sleeve means having to use a chest heart rate monitor instead of the optical one. This appears to be a design flaw that cannot be fixed with firmware!

  • I reported poor elevation accuracy and provided comparisons with a vivoactive3 & a edge820explore recorded on the same rides. The only advice garmin support provided was to manually calibrate the instincts altimeter before each ride . Which was only partially successful, the rides were MTB rides around a very undulating wood and the instinct elevation traces were both off for elevation at start but also they lacked accuracy in tracking the elevation changes. I could “fix” these by applying elevation corrections to the recorded ride in garmin connect. Since update 5.70 the instincts elevation tracks better follow the terrain but still often have inaccurate elevation levels recorded at the start even when I previously calibrated the level via gps. I plan on changing the setting from auto to altimeter for my next ride as my usual terrain is very undulating to see if that helps. 

  • I've been having similar issue with measuring elevation on my hikes. For the same trail, the measurements ranged from 800 ft to 3400 ft over several hikes. I was asked(by Garmin support) to clean the area with the sensor port and retry(which I am going to try). After reading all the comments, I am not sure if it'll really help.

  • When the Instinct is worn on the wrist, however, with the sensor opening positioned so close to the skin, sweat and dirt block the sensor opening leading to errors.

    At first I had similar problems with my Instinct, but eventually I learned how to use it, without having any significant troubles with the altimeter. First of all I carefully rinse the watch after each activity, and blow out water from the pressure sensor opening. And then, during the activity, I dry the wrist under the sensor opening, up and then. Either with a sleeve, or when I have none, then just with the fingers of the other hand. It works pretty well. At the beginning I was often accidentally hitting one of the buttons when doing it, but eventually I learn doing it without this hindrance.

    Thing is, wearing the watch over an arm sleeve means having to use a chest heart rate monitor instead of the optical one.

    Actually, not really. I wanted to test something by hindering the HR from properly functioning, so attached it over a sleeve, and it still worked. I taped the optical sensor with a duct tape, and it still worked. I added a piece of leather and it still worked. I used a metalized foil and it still worked. I had to use a combination of metal foil and an inuslating layer to finally make it fail. It means the sensor captures not only visible light, but also IR, and can hence detect even the slight heat variability caused both by.radiation (through textile or tape), and conduction (through the metalic foil).

    However, I would not really recommend using it in this way - it would not only make it less sensitive, but also more prone to false signals due to the ambient light, and due to the arm motion, and especially it would significantly increase the battery drain, since the OHRM would use more intensive light to get sufficient signal.

    What you could try, if my advise to dry the wrist with a sleeve or with fingers did not help, is glueing a piece of foam or a textile mesh over the side, where the sensor orifice is. Or wearing a narrow sweat wristband on the side of the watch (not under it, where it would hinder the OHRM).

  • See my post here

    Seems to work, doesn’t block the HRM and is dead easy and cheap to implement :)

  • It seems that link goes to your profile instead topic. Could you please share this solution?

  • Sorry about that, I just changed the link.  I couldn’t figure out how to link a post so I linked to the thread.  

  • Thumbsup I’d be interested to hear how that works for you.  I’m pretty convinced from what I’ve seen so far but there are lots of variables at play here so it’s always tricky to be 100% sure.

  • Nice try, but not solving any issues with described methods. I used Instinct in combination with 2 other watches, Garmin 645 and Huawei GT2e. All 3 watches have altimeter. Instinct is constantly worse when comparing elevation changes. When running Instinct is reporting catastrophic elevation changes, no matter if I am sweating or not. When cycling the altitude graph is ridiculous. What is most funny (or sad) is that, Huawei (the cheapest watch of the bunch) is reporting almost perfect altitude... Instinct was used with 6.60 update and last 2 cycling trips with 7.0 update. I am really furious. I don't know what Garmin wants from us? To shave our arms and not to sweat during the activity? Remember, we paid extra for barometer...

  • Agree. There is a major problem with this model, and Garmin would not admit it. I now have my 3rd Instinct, in matter of weeks, replaced without charge or explanation. Same problem even on the first day after unboxing. It has nothing to do with sweat, dirt or port positioning. It simply doesn't work, so much so that it is misleading. Altitude /Asent is critical information for cycling. Repeating exactly the same 30km ride I have seen asent readings ranging under 400m to more than 1800m. What is also driving me insane it that the dealer now wants to sell me a Fenix for more than double the price. I don't know what the solution is.