Zwift & Optical HRM

Historically I always used heart rate straps when zwifting. However, there were often issues that it didn’t register anything, heart rate ridiculously low or at times ridiculously high. Very dependent on the strap as well. Some never properly worked (new out of the box) or worked but died relatively quickly.

My watch, Garmin, always reads a HR but pairing it to Zwift is annoying as one needs to start an activity on the watch. Instead I opted to buy the Polar OH1. First time it seemed fine but ever since it reads very low. Normally in Zwift races I average something in 150 but with the OH1 it’s low 120s. Switched around arm and location to no avail.

Only now I also paid attention to watch on my wrist. Running outdoor it seems correct but when Zwifting it reads even lower than my OH1 (6-8 bpm).

Therefore my question: Anyone else has issues with optical HRM and zwifting? That it reads really low while chest strap reads correctly. Is it possibly the position on bike (vs running), location (indoor vs outside), something else? As I’m dying and heart rate of 120 does not really align then.

i use an oh1. the strap needs to really be quite tight, or you will get a low reading. also, and yes i have done this myself before, check you didn’t clip the sensor in inside out. somehow it still produces a reading if you do that, but it will be really low

you probably just need the strap tighter. no idea about the garmin though

re the Garmin watch, I know on my Forerunner 245 i can set it to broadcast heart rate all the time, however it does kill the battery which is why garmin normally broadcast during an activity

I use an optical HRM (Coospo HW706) and I also have a Garmin HRM-DUAL chest strap. They read approximately the same and the optical unit is quite trouble free. It’s not necessary for it to be super tight, just not floppy loose or with the sensor over the hairiest part of my arm. I’ve heard that darker skin pigment can interfere with them but I have no direct experience with that.

Thanks. Thought it was quite tight but will check again. Also position of it but quite sure that was fine as well, I’m blonde though so who knows!

Anyway, others then don’t seem to have the same issues? Odd that I have it with both. As said never paid attention to the Garmin before but looking back the max is significantly lower than reality for historical Zwift sessions, e.g. ZRL races on Tuesdays where my Garmin watch had a max of 135,141, etc (but occasionally seems more correct). Hence seems optical doesn’t work for me (and I’m almost albino).

to be honest, i really wouldn’t notice if it were 5-10bpm off, but i don’t really have any issues. not sure if this is the best place to wear it but i wear mine mounted on my lower bicep with the sensor on the inside of my arm, facing the basilic vein (i had to google that), seems fine there

Thanks! Charged it and reconnected it but only did a zone two ride so can’t tell yet if anything has resolved. I’m thinking now it might have been connected loosely or something, although it does not explain why my Garmin Forerunner 245 reads low during Zwift (and not when running outside) but let’s see. Shifting stopped working on my kickr bike so can’t get my heart rate up on a low gear to test. :slight_smile:

I just started using my Garmin watch as a temporary HRM and it seems that it has a very difficult time tracking anything above 110bpm. Far from accurate but better than nothing, I suppose. I blame Garmin for that, not Zwift.

Not sure if this is relevant but I’ve just bought a FitBit Charge 6, as a back-up when I ride, it connects to Zwift but does not show a HR, not sure why.

Took a while to properly test as shifting stopped working on my kickr bike, so handlebars had to be replaced (good service by Wahoo though).

Yesterday it kept reading high. Even got stuck at a constant 215 bpm (which is well above my max). So now it doesn’t read low anymore but high instead.

It’s placed in correctly (triple checked) in the band, placed on my left upper arm and tried mutilple positions without significant change. Well, it was distracting enough during the race to get dropped and gave up. :slight_smile: During this my Garmin watch was still under reading significantly.

Something doesn’t work for me at least sitting on the indoor trainer. So back to straps it is…

sounds like it’s just busted. polar stuff is supposed to just work but in my experience hrms in general have terrible QC. if it’s working properly it should give a semi decent reading most places on the body as long as it’s fixed properly