Suunto SHRB2 Firmware 3.2.6.8 Update

[matram]

@wakarimasen
These are some typical values for me …

Device	VO (cm)
Race 2 from wrist	6.3
SHRB2 from chest	5.1
Stryd Duo from foot	5.7

Which value is correct is not obvious to me.

[wakarimasen]

@2b2bff said:

@wakarimasen said:

Have any other SHRB2 users, that are in a position to compare with wrist based data, seen a similar result?

I found the same. Garmin (Epix Pro and Fenix 8 in my case) gives a bit more than the HRM2. It is 8.x vs. 7.x cm in an easy steady run for me. Hard to say what is closer to the truth…

@matram said:

@wakarimasen
These are some typical values for me …

Device	VO (cm)
Race 2 from wrist	6.3
SHRB2 from chest	5.1
Stryd Duo from foot	5.7

Which value is correct is not obvious to me.

Thanks both! For me it makes sense the wrist-based measurement would be higher, but of course it’s just a guess in the end.

[johann.fuehrer]

@matram I would prefer the chest measurement, as there is no need for compensation calculations for leg/foot or arm/wrist movement to get the “real” vertical only data… my 5c

[snow*]

I’ve tried countless ways to protect the sensor, with esd tape, bags, and so on, but in the end I didn’t find a truly game-changing solution worth considering for me. Instead, I found a fix that mostly works for me: water. All I need to do is dip the starp in water and put it on as is. The trouble I had appeared in the first 15-20 minutes and wetting the strap probably helps. YMMV, ofc…

[VoiGAS]

@snow interesting, maybe I didn’t use enough water… do you wear polyester shirts or natural stuff like cotton, merino or tencel?

[snow*]

@VoiGAS said:

@snow interesting, maybe I didn’t use enough water… do you wear polyester shirts or natural stuff like cotton, merino or tencel?

At the moment, I’m using the lcebreaker Tech Lite,
made of 100% merino wool.

[VoiGAS]

@snow I guess this also helps preventing artifacts

[VoiGAS]

Tried it today with wet belt and Merino Shirt. No artifacts

Unfortunately my skin doesn’t like Merino too much. Hopefully there will be a way to get good quality with polyester too…

[Inge Nallsson]

@VoiGAS said:

Tried it today with wet belt and Merino Shirt. No artifacts

While my latest running session got totally destroyed by HRV faults! OK, I used three layers of polyester on the torso (autumn is starting to bite), but also a 70 mm length of rubber tubing as ESD shielding - the length still doesn’t interfere with the strap electrodes.

I had done a factory reset of the SHRM2 to see if the Flight Time impossibility numbers would correct themselves. The did not on today’s trail run (Avg. 2 ms FT over 6 km…), though I’ll make a separate post about a couple of experiments yesterday.

Even if some ESD circumvented my rubber tube, the disturbance should not have disrupted the HRV readings in such a severe manner as below. My guess is that the HR monitor suffers from major bugs in the software.

Anomalies 22.5%
Artifacts 37.6%

Runalyze R-R graph:

Suunto App. Most of the HR also got corrupted:

Garmin Forerunner 955 control watch. Correct HR:

[VoiGAS]

@Inge-Nallsson Wow, thats even worse than everything I produced with the first Gen Smart Sensor. Really seems to be the Shirts material, but even then I don’t think Gen2 works better than Gen1. More likely to be the other way round which raises the question what’s behind the claim of having a better signal quality with the new belt

[atoponce]

@Inge-Nallsson As much as the data was pointing to the module itself, I’ve started wondering if the strap is picking up ESD. Despite every effort I’ve thrown at the problem to eliminate ESD at the module, it still shows up in the R-R interval data.

Regardless, if the ESD is picked up at the module or at the strap, the marketing promised that this would be mitigated in the firmware, but I’m not seeing it. I specifically purchased this HRM because I was battling this with my Polar H10, and the feature that artifacts would be removed was promising! In practice though, where the rubber meets the road, it’s not doing anything any other HRM on the market isn’t doing.

As it sits, ZoneSense isn’t trustworthy for me. When the first 12-15 minutes look like this, how do I know ZoneSense has a good baseline for the rest of the run? This was a 10×3:00 threshold interval run this morning.

[stromdiddily]

@atoponce where do you find this graphic?

[2b2bff]

@stromdiddily Runalyze…

[Inge Nallsson]

@atoponce said:

As it sits, ZoneSense isn’t trustworthy for me.

Exactly. Also, never knowing if base HR figures are correct or not (without using a control watch) takes the pain too far. Today I packed the SHRM2 up, this my second unit to try, and shipped to the seller asking for a refund. I lack the stamina necessary to continue experimenting and wondering.

[stromdiddily]

@2b2bff said:

@stromdiddily Runalyze…

haha yeah, got that…there are 500 different tabs and analytics links in Runalyze, which one shows this? The closest thing I can find is aerobic estimation but it doesn’t look like this graph.

[snow*]

@stromdiddily If you want to take a quick and easy look at R-R data, I recommend

https://smlanal.szmigiel.design/

Just upload the activity’s .json file, and you’re all set

[atoponce]

@stromdiddily When clicking on an activity, scrolling to the bottom there is a “Heart Rate Variability” box. This is in the new site redesign.

[stromdiddily]

@atoponce thanks!! I somehow had “hide hrv plot” checked so wasn’t seeing that

this…doesn’t look great for a completely steady treadmill effort

[atoponce]

@stromdiddily Yup. I have no idea how to fix this. Chest strap HRM’s should be “plug-n-play”, but that’s definitely not the case with this one.

I use electrode gel with the strap, spritz the front of my shirt, and have a anti-static bag taped over the module, and I still get data that looks like this:

[Dimitrios Kanellopoulos]

If you want HRV analysis also quantified-self.io offers this for free FYI

just upload a normal fit file
Screenshot 2026-10-23 at 18.18.46
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