Jan, You will probably find most of the discussion on this topic here. https://forum.suunto.com/topic/15822/suunto-smart-heart-rate-belt-2/240 I also upgraded from H10 to SHRM2 and have actually not had any problems. But others have had. It seems a factory reset might help and the type of material in your T-shirt may affect the sensor. Good luck getting the problem solved.

@snow Maybe, I could buy that for a very slow recovery run at 7 - 8 min pace. But 4:10 pace is very close to my absolute limit and it sure does not feel like I am speed walking. But it seems like I am in good company with other walkers It comes back to, if GCT is for one foot per step or for both feet per stride, the rest follows mathematically. I guess Suunto should provide an authorative answer to clear up the confusion.

@snow that would make sense

@mirod73 it does not work for me as well (android)

Suunto has already explained this in the official ZoneSense FAQ: Why does ZoneSense require a heart rate belt? To get accurate measurement of one’s heartbeat requires a heart rate belt. This data is essential for detecting differences between R-R peaks in heart rate. Optical heart rate monitors can only perform this type of measurement reliably at rest, such as during sleep. Can ZoneSense be used with an arm heart rate monitor? Arm heart rate monitors use optical heartrate. This cannot be used to measure the beat to beat data accurately during exercise, therefore ZoneSense is not available for these sensors.

Update 05.September, I have bought a new Smart Heart Rate Belt 1 with Sensor (older generation) to test the older Strap with the new Sensor, but same issues, drops, freezing, I will send the Sensor back to get an spare Sensor.

I just ran the race and didn’t have any problems at all with the new heart rate belt or the sensor. It seems that resetting the sensor helped. I’m also going to test my old heart rate belt with the sensor just to see if it might have something to do with the old belt. [image: 1790056282643-4cd90b0b-9bf9-4f08-8c93-973125f751dc-image.jpeg] greez

@CroShark Report your problem to suunto support@suunto.com Have to say, I have reported it multiple times (my race s looses it’s connection to my polar oh1+ and stryd quite regularly), but I don’t think suunto is actually working to fix the problem. They told me not to expect a firmware with a fix anytime soon (and I think anytime, for my race s) Do have to say, regularly reboots (as in every week) does mitigate the problem.

Another interesting feedback from this reviewer, in which he noted some strange behaviour from the HRM2 (the sensor was stuck at 150 bpm). Here is where he discusses it. FWIW it worked without a hitch for me today… but that’s just a one shot. I’ll keep an eye on the matter.

@vinc14 I’ve got the same problem: my son jumped into the swimming pool, but in my case the HR was actually closed properly, although there was water in the battery compartment as well. So I think the problem might not be that it didn’t close properly, but rather a fault with the HR IP’s seal. I’d send it back to Suunto, but the problem is that I can’t find my invoice any more.

@Mauerwegler Hey guys, late response, but could help others as the app and docs aren’t intuitive. To pair the sensor, go to the app settings, then go to Activity & training, and click Pair HR sensor. Hope it helps. I don’t know why it’s not located with the pair device button on the home screen. I also searched for quite some time…

@Elipsus no worries, I just shared the “why” : )

@halajos Looks very much like clone, or exactly the same product under different branding, of Morpheus M7 HR belt. Morpheus works great for ZoneSense, plus I haven’t experienced any drops or disconnections like many people report here with their Suunto belt or Polar H10. Around $40, looks like a solid choice compared to M7 at ~$100.

@2b2bff Interesting, that’s good to know and I might give the Coros HRM a try whenever the Polar decides to pack up. With it on my upper forearm it doesn’t bother me at all, if I’m wearing long sleeves it just sits underneath whatever I’m wearing

@Blaz-Kelbl Hi. All the watches I have used (Suunto, Garmin, Polar) cannot measure heart rate from the wrist properly. Sometimes they succeed very well and sometimes very bad. Heart rate belt is the only way if you need/want exact reading. Best Regards Pasi

@PIPA44800 exactly, this is not a support but a Community forum.

ah okay, thanks for the replies. That is unfortunate. It happened twice already that I didn’t manually switch to the other device (i switch between the two every day so they can properly dry before I use them again) and I only got pulse based heart rate without zonesense for the activity.

After days of using Race 2 HRV i decided to give a try to Suunto Chest Strap again. Yesterday on shopping i bought new CR2025 batteries different brand (Energizer) I put new battery to strap. Wet electrodes of strap. Connected strap with Race 2 succesfully + get strap on my chest. 100% Chest strap battery. I DIDNT start exercise. I just took off chest strap + I took off sensor from belt, everything was laying separate. Next day I started exercise with strap - it was magically 20% batttery left before I started to run. Lost 80% during 24h without using it and having sensor taken off from belt with dry strap so its impossible it could work anyway + battery should last 500h. Next day I started running exercise with 20% battery in sensor, ended up and magically Race2 shows it got 30% battery left Did 40 minutes gym session - still 30% battery. Now i know its not batteries fault. Its sensor from strap/Race2 software that reads wrong battery status or problems with connecting BT. or watch itself. Its my probably last try and post, just wanted to give a info