Garmin HR monitor going wild

Hi everyone,

Since about two weeks, my Garmin HR monitor (HRM dual) is acting wild. When my HR go up, my monitor is displaying big numbers. When doing endurance, I am usually between 120 and 130 and I see MY HR going to 160 at least and up to 200. When my HR go down, the value displayed go back to normal.
Battery is recent, strap too and is washed regularly.
It doesn’t bug everytime, I noticed it did when riding with my father who has the same monitor. And today it did while I was riding solo but I just added a cadence sensor.
It seems to be cause by interference with other devices.

Did you have the same issue, is there a solution ?

Thanks for your help !

I’ve had this happen a couple of times and both times I put in a new battery and it didn’t repeat. Just last month it showed me at 177 bpm where it was probably about the 130 range in reality. I know you said recent battery but if you have another one handy it might not hurt to swap it out just to rule that out. It only takes a couple of minutes to change.

1 Like

Connected over BLE or ANT+?

If bluetooth… there is your problem… bluetooth should only be used for Firmware Updates

Usually ANT+ solves connection issues

Weird Data!


Switch whatever way it is connected and see if you can replicate?

1 Like

I forgot the newer models support BLE so that could be a likely culprit too. My ancient strap only does ANT+.

1 Like

@TheOtherOne @TheOtherOne Thank you guys, it seems likely bluetooth is the culprit. If not, i’ll try to change the battery.

@rockrabbit - Just wanted to point out in case someone comes across this thread in the future that the Garmin HRM-Dual is perfectly usable with Bluetooth. It even has 2 Bluetooth channels so you can connect it to 2 apps or head units in addition to Ant+.

HR was already connected via ANT+. I changed the battery even though the previous one was less than 5 months old and so far so good.

1 Like

Also worth rinsing the strap after every use - keeps them in decent condition for longer.

I have the old (ANT+ only) garmin premium strap. In use for 2 years with the original battery. I had this issue once now… Did a recovery ride outside and tried to keep my HR ~130, but it was rising quickly to 179 (without any effort on the bike) and just the same it dropped quickly back down to ~120 (within 1 minute). Not sure if it was an error of the strap, some interference, of maybe my heart reacting on something (it was quite cold, more then expected and I wasn’t warm yet).
But again, this was only once in 2 years. Outside I spent most time on the MTB, so not much time to look at HR (so it might have happen more often), but for 6 months indoors now and never saw a spike like this.

I always rinse mine off along with my helmet and Headsweats immediately after every ride and my strap from 2015 is still going strong even using it 5-7 days/week.

1 Like

This…and Garmin straps in the past have been susceptible to a build-up of static electricity, especially when first starting a run. Had this happen often and I would do and moisten the unit to reduce the charge. Also happened occasionally on the bike, but definitely more often when running.

Even resorted to spraying it and my shirt with Static Guard sometimes…

1 Like