Suunto Smart Heart Rate Belt 2

[2b2bff]

@Inge-Nallsson my first run with the SHRM2 had the same bad heart rate experience. But to be fair, I used the older strap and possibly headn’t wetten the belt enough. After a while the reading normalized. Runalyze showed r-r readings all over the place for the first part of my run.

The other times I used the SHRM2 with the new belt and HR reading has been like you would expect them to be.

I guess the new in sensor error correction code is not doing well under all circumstances.

[snow*]

@Inge-Nallsson said:

@matram said:

Mybe time to dig out my Stryd pods for a comparison

I could not resist the temptation, even though my injuries forced a really short experimental run. So, Suunto Race S connected to the SHRM2, Stryd ‘Wind’ (model Nr 19) pod on the left shoe (Altra Torin 7; a Zero-Drop/flat model) connected to the Stryd App on the phone, and finally Garmin Forerunner 955 with native running dynamics capability on the left wrist.

Total running session 1 kilometre in 7 minutes on practically flat asphalt (4-5 metres asc/desc). Cadence ca 175 spm, Average Ground Contact Time and Average Vertical Oscillation below:

SHRM2 – StrydW – FR955
354 ms – 319 ms – 273 ms
5.7 cm – 4.78 cm – 7.6 cm

354 is 29.67% higher than 273 according to Google, and that is also the ca 30% difference I had in mind from old experiments. The Suunto info then says I’m either Fair: 270–300 ms or Poor: 300 ms. But I bounce around with the efficiency of an Elite: <6 cm or at least is Very good: 6–8 cm. I stopped looking at these numbers a long, long time ago…

The shockingly bad experience with the SHRM2 was the Heart Rate. Strap was firmly secured and wet before the run. This is either a serious pod firmware bug OR a Race S firmware bug:

Look at that HR of 32 bpm! Even lower than the lowest I’ve seen while sleeping and wearing a Holter monitor (39 bpm).

I can’t comment on the running dynamics yet, and the only thing I have a complaint about (though I need to look into it further) is the noise in the R-R; that said, there is something strange about your unit, afaic my heart rate reading is fine.

e.g. no idea what happened to R-R after 15’

[VoiGAS]

Got my HRM2 today and did a short Test Run with the RaceS. Thoughts:

• The belt is not really wider or more comfortable. Maybe a little bit more flexible
• Real Time Dynamics are not easy to read during the run, but I had the possibility to react to the bad GCT with better technique and reduced it. So it makes sense
• GCT Balance is somehow strange. I have a hurt right leg with metal in it - but still the balance tends to the left. Not sure if I trust it
• Zonesense looks much better. Clean line in Runalyze and proper detected aerobic threshold

All in all a positive first experience, but I am not sure if its worth buying if you already have a (good) belt. For everyone not owning a HR belt its highly recommended.

[Inge Nallsson]

@snow said:

there is something strange about your unit, afaic my heart rate reading is fine

Quite possibly. Paired the SHRM2 with the Garmin FR955 as well as the Race S and redid the 1 km run a few minutes ago. They both mirrored a crappy first minutes. And the FR955 had a couple of late spikes not seen on the Race S graph (perhaps the FR955 tried optical HR there…) I will redo the run tomorrow morning with optical forcefully turned off in both watches. If crappy HR again, the SHRM2 goes back to the seller. Race S:

Garmin FR955:

[snow*]

@Inge-Nallsson before sending it back I would also try a factory reset…

[2b2bff]

@Inge-Nallsson said:

(perhaps the FR955 tried optical HR there…)

You can see this when using fitfileviewer… Garmin does record three heart rate streams. Wrist based, external and just “heart rate” what is represented by the graph in Garmin Connect…

[Squirrel]

@snow said:

would also try a factory reset

Of the belt?

[snow*]

@Squirrel yep. Press the button for 20 sec until you see red green blue sequence (not sure in that order). You also need to cancel every past pairing from devices…

[atoponce]

@VoiGAS Can you share a before/after of your RR data and ZS charts by chance?

[HonzaS]

Oh God . You want to buy best compatible accessories and got this . Also I can’t believe, that I’ll have somehow better Zone sense readings with SHRM2 compared to Polar H10. It’s only about R-R intervals and good signal IMHO. I’m glad for my H10. I only got strange R-R readings while I have extrasystoles during activity which I feel very well. I got ECG holter implanted. It’s a long story. But last months everything is fine and I feel it only time to time and also my R-R difference charts from cycling are perfectly clear.

[Mitch9]

@HonzaS It’s hard to interpret the date if the scales are not equal and we don’t know wich data belongs to which source.

[VoiGAS]

@atoponce only the new one

Still some noise, but thats normal in the first few minutes. The old one was more like a bee swarm…

Edit: Must have been cheating to myself. Looks similar, not easy to compare because of the length. Thats why I thought the line is thinner…

[atoponce]

@VoiGAS Thanks. That is a lot cleaner than my data with my Polar H10. Here’s an easy run when I was tapering for a 50K recently:

And Runalyze’s view of ZS:

[Inge Nallsson]

@snow said:

before sending it back I would also try a factory reset…

Removed the SHRM2 pairing from the FR955, Race S and Suunto App. Did the 20+ seconds factory reset and repaired the monitor to all devices again. Redid the 1 km running experiment with optical HR specifically and completely turned off in both watches. While the live HR data during the run looked plausible, there were oddities like 3-5 bpm differences between the watches (they should practically mirror eachother) and HR dips on a flat course that should see a slow steady bpm increase.

Stopped and saved, the session HR graph looked ‘OK’ on the Garmin but completely mangled on the Suunto. FR955:

Race S:

The HR graph in the Suunto App does not look mangled in that manner, but the dip right before the 3 minutes mark is very prominent. I’ve put the marker in both graphs at 6 min 10 sec on a flat section that signifies an obvious loss of signal. Suunto:

Garmin:

I will definitely initiate a return of the SHRM2. The faith in this unit is lost and questions about the overall hardware/software interactions are raised in my mind. Too bad… My Polar H10 died after a couple of years service and the ‘Suunto Smart Heart Rate Belt’ lasted only a bit more than a year (yeah, the pod became erratic). Optical HR is not a good option in the fast approaching winter conditions.

[Inge Nallsson]

@2b2bff said:

You can see this when using fitfileviewer

Yes, but that site is such a pain to use on a phone. Hard to scroll, search and get a good view unless you have a mouse and a large screen. Would first have to mail the .fit file to myself before pulling it down to a seldom booted up computer… Too many hoops to jump unless being on an important quest.

[snow*]

@Inge-Nallsson I absolutely have to check if I get the same problem when using multiple channels.

[HonzaS]

@Mitch9 said:

@HonzaS It’s hard to interpret the date if the scales are not equal and we don’t know wich data belongs to which source.

They are three bike rides. This is the yesterday´s ride:

[2b2bff]

@Inge-Nallsson point taken. I’m one of the people who still use a computer regularly and don’t force myself to do everything on a mobile phone…

[snow*]

I’ve proceeded with a factory reset and :

slow run:

step up box:

and another good one from yesterday, so afaic issue seems solved:

[matram]

It seems to me that the numbers we see for GCT and FT in the app are for a full stride (left plus right leg) while the guidance numbers are for a single step?

From the Suunto app for a recent run (72 year old and slow runner if you wonder):
Average cadence 76 rpm
Average step length 158 cm
Avg GCT 449 ms
Avg FT 334 ms
GCT/FT relationship 1.336
Vertical oscillation 5.1 cm
GCT balance 51.6% - 48.4%

Computing the cadence from GCT and FT - 60 / (0.449 + 0.334) = 60 / 0.783 = 76.6 rpm matches the 76 rpm cadence.

The guidance numbers are
GCT
Elite < 210 ms
Excellent 210 - 240
Good 240 - 270
Average 270 - 300
Poor > 300

FT
Jogging 80 - 120 ms
Stable 100 - 150
Fast 120 - 180
Sprint 180 - 250

If you take the average of GCT and FT, e.g. 250 + 150 ms, you get a cadence of 150, clearly for a single leg.

Maybe Suunto would like to clarify this? I do believe it is correct to show the numbers for a complete stride. It is the guidance numbers that are confusing.

At least I hope I am not “Extremely poor”