Suunto SHRB2 Firmware 3.2.6.8 Update

ggrego

Hello, did he notice that since the update the belt remained on standby? It no longer cuts. The sensor connects directly to the watch even without being attached to the strap

Speed Man

@ggrego The device will automatically turn off after 3 minutes without contact with the module.

ggrego

Not for me it remains active even without the strap after several hours

matram

A correction to my previous post first. The formula I used, GCT × step cadence / 60, gives GCT / step time, not duty factor. Duty factor is defined per stride (two steps):

Duty factor = GCT × step cadence / 120 (GCT in seconds)

So the boundary for “no flight phase” is DF = 0.5, not 1.0. My conclusion that GCT > step time was still correct for those numbers, but the numbers were wrong.

I analysed Suunto (FW 3.2.6.8) and Stryd Duo FIT files second by second and looked at each workout segment, skipping the first 6 s of the 20 s intervals and the first 10 s of longer

Segment	Pace	spm	GCT Suunto	GCT Stryd	Flight Suunto	Flight Stryd	DF Suunto	DF Stryd
Easy (10 min)	8:06	157	436	425	−51	−42	0.57	0.55
20 s interval	3:51	211	250	224	+49	+61	0.42	0.39
20 s interval	4:12	202	263	239	+39	+58	0.43	0.40
90 s interval	5:22	178	344	309	−5	+29	0.51	0.46
Walking recovery	~11:00	110	~470	~650	+75	−110	0.44	0.60

(GCT and flight time in ms. Flight time = 60 / cadence − GCT.)

What I see:

Suunto’s GCT lags about 6 s. At the start of each interval it holds the previous walking value (480 ms) for several seconds before dropping to about 245 ms. In a 20 s lap this pulls the lap average up a lot, which explains the 297 ms I reported earlier. The steady part of that interval was about 245 ms, with a clear flight phase.
When running, Suunto’s GCT is about 25–35 ms longer than Stryd’s. Near the boundary that’s enough to turn a positive flight time negative: −5 ms versus +29 ms in my 90 s interval.
During walking, Suunto shows a near-constant 465–480 ms and positive flight time, which can’t be right for walking. Stryd shows about 650 ms (DF 0.60), a normal walking value. It looks like Suunto’s GCT isn’t measured directly in that range.
At easy pace, both devices agree that I have no flight phase (DF about 0.55). That’s not walking, though. It’s “grounded running”: running mechanics, with the body lowest at midstance, but one foot touches down before the other leaves. It’s common at slow paces, especially for us older runners.

So for anyone puzzled by odd flight times: check the second-by-second data and skip the start of any short laps before drawing conclusions. Over longer steady segments, Suunto and Stryd are fairly close, with Suunto reading somewhat longer GCT.

wakarimasen

One aspect of this device that I’m interested in is the information related to vertical oscillation. It’s an area that I think I need to improve (more forward motion and less ‘up and down’) but that is based on the data generated by the Garmin 955 that I sometimes wear. I noticed that in the comparison between SHRB2 and a Garmin 955 (a few posts earlier) the latter showed a higher number for VO, compared to the Suunto device. This makes sense to me, as it must surely be more difficult to measure this characteristic using a device that’s being swung back and forth, whilst simultaneously going up and down, compared with something that’s fixed to the torso.

Have any other SHRB2 users, that are in a position to compare with wrist based data, seen a similar result? I ask because no matter how ‘carefully’ I run, the Garmin 955 still says I’m bobbing up and down like pogo stick!

2b2bff

@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

@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…