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Problem with HRM-2 Sensor/Strap and Forerunner 235

Scorp1981
over 8 years ago
My wife's 235 is having some strange issues with a HR strap. From the beginning:

She always used Polar straps and watches. Never had an issue. I then bought her a Forerunner 235 and gave her my old HRM-2 Sensor, which i had bought many years ago with my first Garmin Device (I myself use an old HRM-Run or my Wahoo Tickr anyway). I only gave her the sensor, since the original strap had stopped working a long time before, and I then used it with a Polar Strap (always worked like a charm).

But on her first run (using her own Polar Strap, with which she had never experienced any Problems), the Sensor gave some very erratic Data (HRM below 100, when it was definately well over 140). We tried everything, from soaking it with water (planned to hike after the run, so I had my Source Widepack with me), cleaning the buttons(?) on the sensor, re-pairing it, etc. Did not work. She then had to turn off the Sensor on the Watch and run with the OHR (doesn't work too bad, but we both like the Data to be more exact).

Afterwards, I then checked the battery and sure enough, it was almost empty. I replaced said battery and took her Forerunner 235, my VAHR and my Forerunner 620 for a run. I paired my Forerunner 620 to my HRM-Run strap and the 235 and VAHR to the HRM-2 Sensor (using, just for precaution, a brand new Garmin Premium Strap). I started running and suddenly the HRM-2 Sensor on both my VAHR and the Forerunner 235 spiked to 155, whereas my Forerunner showed the (most probabely proper) reading of 119. After about one or two minutes, the HRM-2 seemed to settle, but only on my VAHR, not on the 235, which was showing some very erratic Data (jumping from 130 to 150, and so on). I turned the 235 around my wrist, since I was wearing it face-down. It almost suddenly settled down as well. For the rest of my Run (about an hour), all 3 watches agreed perfectely. I took this as a sign that the HRM-2 works properly (albeit needing a minute or two to settle down), and I learned, that the 235 should not be worn face-down (I didn't know, sorry if this is supposed be common knowledge).

Yesterday my wife and I went for another run. Just for precaution, she wore the HRM-2 with the very same Garmin Premium Strap as I had before. Unfortunately, it again showed readings of below 100, even declining with every minute. After 5 minutes it still didn't settle. Since I had taken my Wahoo Tickr as a reserve (should she still have problems), I gave it to her and, after about 30 seconds of needing to settle, her 235 showed finally some realistic readings throughout the whole run (also about one hour).

I'm perplexed. I don't know what could be the Problem. With me, it worked flawlessly as soon as I wore the 235 properly on my wrist. With her, it never seems to work, even when using the same (brand new) Strap as I have (which worked fine with me). It cannot be the placement. She places the chest strap with the HRM-2 the same way as her Polar Straps and the Wahoo Strap.

My next test would involve her wearing the HRM-2 Strap again, while paired to her 235 and my VAHR, so I can see if it is only her 235 which gets the erratic reading. But after this, I don't know. And I don't know when I will be able to do this since I work shifts and we won't be able to run together for some time.

Has anyone experienced the same Problems? Could it be just the 235 having a Problem or is it more probabely the sensor that is not working as it should? I would be very grateful for some advice.

Please forgive me if I didn't explain myself properly. My english skills are not what they used to be.

(P.S. my wife doesn't speak english at all, that's why I'm writing for her)
  • 0 over 8 years ago
    Personally I've found the Polar straps to be much more consistent with the Garmin HR module that the Garmin straps. Note, later Polar strap has a raised rim of soft plastic that needs to be trimmed down to allow the Garmin module to snap in. Point is, hang on to those old Polar straps.

    Second tip concerns getting a good electrical contact going, which I suspect may be your wife's problem. Before I put on my chest monitor I ALWAYS spit into the palm of my hand and wipe it across my chest where the contact pads on the strap are. Yeah, it may sound a bit unsanitary but saliva is actually a fairly conductive liquid and it's slow enough drying that it will keep the electrical contact path going until you get a good sweat going.

    Finally, too much salt from sweat can cause issues. In my experience usually the monitor reading high and climbing even if you are laying on the ground watching the clouds. I now have 3 chest straps in my rotation and after every exercise activity the used strap goes into a bowl of water for an overnight soak then it's hung up to dry in the morning. I also put my chest straps into the clothes washer with a load of laundry once per week. By doing this I now have nearly 9 months of accurate readings without one single incident where the chest monitor went goofy.

    BTW, I have found the wrist monitor isn't accurate for ANY activity where I am moving faster than about a 22 minute per mile pace. Basically it's only useful when I am sitting at a computer, watching TV, or sleeping. If I am doing anything more active than that the only really accurate device is a chest monitor. I've also tried the Schosche Rhythm + and while it is more accurate than the wrist monitor on my 235 I've had too many occasions where it's gone off track to trust it.
  • 0 over 8 years ago
    Thx for the reply :D

    The Problem is, that we tried the sensor with three different straps (Wahoo, Polar and Garmin and all of them fairly wet), but it still gives erratic readings. But only with my wife. My own test (with the same Garmin strap) went without issues. Yesterday she did some bodyweight training and wore again the hrm2 sensor. It, of course, still gave erratic readings. But at least my VAHR (which I had paired with the hrm2 as well) showed the same data. So, at least it seems not to be a problem with her 235.

    It's very strange... Only with my wife and only with the hrm2 we see those issues.

    Well, I'll probabely buy me a Wahoo Tickr X (fingers crossed that they will upgrade it to the new Running Dynamcis standart) and give my normal Wahoo Tickr to my wife.
  • 0 over 8 years ago
    A couple thoughts/concerns on the issue.

    First make sure it says "Ext HR Connected"....and/or make sure green lights are off when you are starting the activity. A few times my sensor has went 'inactive' and I had to re-enable it in the settings. Usually around a time I had to do a hard restart. Could be using the wrist sensor occasionally...mssing up data.

    Another thought is that women often have issues with chest based sensors due to sports bra and other things getting in the way.

    I often have erratic readings while lifting as well - where the reading will just cut out and have a gap for 10-30sec often during a recovery.

    Running activities I have seen it act up with dry/static shirts (very high reading in first mile or two), when I have one headphone tucked into shirt(hitting module...), or just a placement issue (too high or low on chest). Electrode gel or aloe gel can help with maintaining a wet sensor on easy/recovery runs in cold weather.
  • 0 over 8 years ago
    A couple thoughts/concerns on the issue.

    First make sure it says "Ext HR Connected"....and/or make sure green lights are off when you are starting the activity. A few times my sensor has went 'inactive' and I had to re-enable it in the settings. Usually around a time I had to do a hard restart. Could be using the wrist sensor occasionally...mssing up data.

    Another thought is that women often have issues with chest based sensors due to sports bra and other things getting in the way.

    I often have erratic readings while lifting as well - where the reading will just cut out and have a gap for 10-30sec often during a recovery.

    Running activities I have seen it act up with dry/static shirts (very high reading in first mile or two), when I have one headphone tucked into shirt(hitting module...), or just a placement issue (too high or low on chest). Electrode gel or aloe gel can help with maintaining a wet sensor on easy/recovery runs in cold weather.


    Thx for answering :-)

    I had forgotten to mention that we also had tried to turn off OHR, to no avail, unfortunately. Also, my wife placed the strap well under the sports bra, just like she always did.
    The problem with the shirt also came to my mind, but the readings were only high on the first few minutes when I was wearing it. For her, it was constantly low (and even dropping).

    I really was afraid, that her 235 might be faulty, but since my VAHR read the same values last time she wore the HRM2, I'm almost sure it must be the sensor which is faulty. It just confuses me that it only has trouble with her and not with me... (maybe it's a personal Thing :rolleyes: *g*)