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Here's how bad the optical heart rate is on the FR265

lytleric

There are a lot of posts on this forum of users experiencing erratic and/or unreliable heart rate readings from the optical heart rate sensor on the FR265. I am one of those users. I previously had a FR45 and do not recall any major HR inaccuracies from the OHR sensor on that watch. When I upgraded to the FR265 (or what I thought was an upgrade), I was shocked and puzzled that the heart rate reading was all over the place -- usually it was too low (based on what I know by feel) and often jumped up by 10, 15 or more beats from one reading to the next. The "solution," if you want to call it that, was to wear a chest strap. (FWIW, I tried multiple wrist positions and strap tightnesses with no improvement.) But again, I didn't seem have this issue with my FR45, at least not to this degree, so what is going on with the FR265?

I decided to conduct an experiment to see just how bad it is. I also have an Edge 830 that I use for cycling. So I brought my Edge 830 to the gym for a recent strength workout. I wore my chest strap and connected it to my Edge. My FR265 was on my wrist with the optical sensor reading my heart rate. I started activities on both devices simultaneously. After the workout, I downloaded the .csv data into Excel and plotted both sets of HR on the same chart.

Here are the results. The blue line is my heart rate as recorded by the Edge with a chest strap. The orange line is the FR265 with optical heart rate. The workout started with a casual 10-minute steady 7-MPH jog on the treadmill. The peaks that follow are my sets of lifts. 

Note the gap between the Edge and the FR265 -- especially during my treadmill warm-up. What is going on here?? The FR265 was jumping up and down randomly. I have no idea what that random spike is.

Here is my HR during some of the lift sets. Again, the FR265 HR was all over the place and the gap between the two is huge.

Some stats:

Greatest jump from previous reading: Edge: 6 BPM. FR265: 18 BPM. (How can my HR jump 18 BPM within one second? I had 13 readings where it jumped seven or more BPM within one second.)

Average difference between the two devices: 6.27 BPM

Greatest difference between the two devices: 38 BPM

Percentage of readings with more than 10 BPM difference: 20.1%

What this boils down to is that the OHR sensor on the FR265 cannot be trusted and is, in effect, worthless. The question therefore is what, if anything, Garmin is going to do anything about this. Considering the FR265 is no longer a "current model" on Garmin's website and has been superceded by the FR570 as the mid-tier running watch, I'd say the answer to that question is "nothing."

  • 0 in reply to Garmin - KC

    The cold weather / lack of a warm up is the likely culprit for me during the cooler Autumn / Winter months.  A lower blood flow in the wrists for the first 10-20mins or so, then once warmed up the blood flow to the wrists (and watch sensor) catchups up and it operates as expected

  • 0 in reply to 3809324

    I could maybe buy that for myself except that my FR245 worn simultaneously with my FR265 doesn't show the problem and that takes me back to processing of the HR sensor..

  • 0 in reply to Garmin - KC

    The FR245 is reliable with the older firmware version I have 11.60. The FR265 is not reliable with the older firmware I have 21.20.

    There is little chance I will update since the user reports for the later firmware versions suggest the optical HR processing to be worse still, along with the other reported problems..  and Garmin doesn't support backdating to older firmware.

    Exactly why does Garmin not officially support backdating?

    Although, I did just verify that the one version I have I have archived on this computer is 21.20, so I could do an unofficial backdate. The file GPUDATE.GSP file doesn't include detail comments but if the file is examined the version is listed inside.

    It's pretty hard to buy into, that at about 8-10 minutes into a run, with the watch securely tight on my wrist, I switched to a velcro closure strap that has infinite adjustment, suddenly my HR takes an immediate vertical jump and stays there. It's not a spike, it's a leap which doesn't happen using the FR245.  

    4 mile outdoor run 1/5/2026

     

    "However, if you have other examples you can provide that show a distinct difference throughout the activity or a more sudden spike/drop in HR data, we'd be glad to examine those and provide assistance"

    So for my use, that sudden vertical jump to new levels is the problem, which I perceive to be filtering. I do not expect the Optical HR to be as good as a chest strap for instantaneous values but I am expecting it to be at least as good as my FR245. I did a chest strap vs optical HR comparisons (same activities) for the FR245 (long ago) and the comparisons were really pretty darned good.

    Now if you give me back the equivalent accuracy level of the FR245 in the FR265 I will be glad to examine the results and consider the possibility of buying a newer Garmin watch when the time is appropriate.

    Otherwise it's no sale. "Fool me once, shame on you, fool me twice shame on me."

    And by the way, support backdating instead of throwing people off a cliff, REALLY!!

       I do appreciate Garmin chiming in with a (sort of) actual response though.

  • 0 in reply to gxgene1

    Its been a major problem with these watches for a few years so obviously there is no desire to fix it.  My next watch won't be a Garmin - I'll probably just keep my Fenix 6 for occasions when I need maps but the GPS reception on that watch is pretty poor compared to what is available now.  I bought my 255 on the basis of dcrainmakers review praising the OHR accuracy as I wanted to run without a HR strap except for high intensity intervals.  So the OHR must have worked well at some stage.  I won't be forking out for another garmin just to find that they screw it up with "updates"