Stryd Calibration Clarification

fazel

@dimitrios-kanellopoulos Okay - I tried this and maybe I didn’t have good gps, but the next day’s track was way worse.

Calibrated on a mostly straight track but trees and buildings were along the side so maybe that was the issue. The run was 2 hours and measured 22.81 KM. GNSS distance was 23.12 KM - so really not much different from the 1.015 average I’ve seen over a couple of months (on average using Strava corrected distances).

https://quantified-self.io/user/Zj6gOpckgnhBQjWHN5Yno4rp0Bt1/event/3e46640d3a44e37e211296decd0d306a980f5461037b33cae368c89281c0f63a

The next day’s run was 1 hour long on mostly the same trail but with some curves as I ran to it instead of driving. Auto calibrate was off. Stryd distance was 11.09 KM and GNSS distance was 11.61 - so a bigger difference (nearly 5% short).

https://quantified-self.io/user/Zj6gOpckgnhBQjWHN5Yno4rp0Bt1/event/31849765f6f98b4d3a48da033e8698ba9a6ae7ee4b3773af785706d84146177f

So - I unpaired the Stryd and re-paired as a PowerPod - but I guess that doesn’t work because the watch didn’t record power on yesterdays run. I guess it’s only the Ambit’s that allow you to just pull power from the Stryd but use GPS for distance and pace?

Thanks!

Dimitrios Kanellopoulos

@fazel you never pair the stryd as a power pod

Dimitrios Kanellopoulos

@fazel I would calibrate it in a more short distance. Like max 1Km

fazel

@dimitrios-kanellopoulos Okay - will try in a completely open area. Watch’s GPS is so good right now I really don’t need the Stryd for outdoors other than I’ve been using power for stress metrics and would like to be consistent.

Aleksander H

@dimitrios-kanellopoulos said in Stryd Calibration Clarification:

you never pair the stryd as a power pod

Is this just a S9 thing? I’ve got mine paired to my SSU as a power pod and it’s working as I would expect it to .

Dimitrios Kanellopoulos

@aleksander-h oh yes… @fazel it might work if you pair it ONLY as a powerpod

fazel

@dimitrios-kanellopoulos can you confirm a couple of particulars regarding the 9’s behavior when paired with the Stryd?

Auto-calibration on

speed/pace and cadence as well as power from the Stryd
distance is from GPS

Auto-calibration off

speed/pace, cadence, distance and power all from the Stryd
only track from GPS

Also - can you explain how the auto-calibration algorithm behaves is auto-calibrate is left on continuously?

How often does it update?
Is old data thrown away? Only the most recent 15 min or so considered?
Or is it more complicated that that?

Thank you!

Dimitrios Kanellopoulos

@fazel

Auto-calibration on

speed/pace/distance from fusion of gps and stryd. cadence as well as power from the Stryd

Each time you run with autocalibration it updates a value called coefficiency.

So for example if you run 1km gps based and stryd says 800m it will make the coefficiency factor higher.

Then it always uses this factor to fuse the values mentioned above when running using the stryd.

That factor is kept and used even if you turn autocalibration off.

With autocalibration off it’s just not automatically updated.

fazel

@dimitrios-kanellopoulos Thank you.

Dimitrios Kanellopoulos

@fazel to wipe out that factor you can repair the pod. Then it’s last value is reset.

fazel

@dimitrios-kanellopoulos this much I know from trial and error! I feel like (for me) it might be better to leave auto-calibration on, but turn it off if I’m doing something like a trail run.

herlas

@fazel did you get any improvement in distance measurement accuracy with the calibration on for your stryd? Mine gives me a 400 meters difference (short) vs the Suunto 7 GPS for a 10K run, looking for options to have Stryd measuring as accurately as possible as it’s not a cheap device

thx

DMytro

@herlas could this 4% error be mostly from GPS side? If you compare two measurements by subtracting, you’d have to add the absolute errors. So in case the both would have equal errors, you’d get 2% error for stryd, seems reasonable, ain’t it?

fazel

@дима-мельниченко @herlas @Dimitrios-Kanellopoulos here’s my story for today…

I set the calibration factor on the Apple Watch based on around 15 outdoor runs using an average of the difference in distance reported by Stryd vs the Strava corrected distance. This calibration factor was 1.017. I have since run with the Stryd and Apple Watch, and the Suunto with the Stryd paired as both a food pod with “auto-calibrate” turned on, and with it paired as a power pod.

Several days ago I unpaired the Stryd from the Suunto completely then re-paired as a foot pod and ran on the treadmill. What I found strange was the pace and distance reported by the Suunto/Stryd combination was directly in-line with what has been reported with the Apple/Stryd combination after setting the calibration factor. I have run with Stryd for several years on and off, and since I have five kids a load of that running has been on the treadmill in our basement. And since I am obsessive by nature, I am very aware of how far off the Stryd typically is uncalibrated when I run at my easy pace compared to what the treadmill is reporting.

I posted a question on the Stryd Facebook group asking them if the calibration factor was actually stored on the food pod, not the Apple Watch. They did not approve my question! They requested I email support instead. Support just replied saying the calibration factor is stored on the Apple Watch and I should make sure my Suunto watch isn’t doing something funky. But…I am not sure I believe them. I plan to run again tonight on the treadmill and see.

fluca

@dimitrios-kanellopoulos Hello Dimitrios,

should this process work with STRYD v1 (HR strap version) connected as a footpod?
I tried yesterday but on the first run without auto-calibration I got speed approx 130 km/h and 25Km in about 8 minutes:
https://maps.suunto.com/move/ficheral/622488bf3776f1566320daf1

Second run with auto-calibration on did not improve:
https://maps.suunto.com/move/ficheral/622488c629c5c10fff6c48a5

Did I do something wrong or this hold version of STRYD is just not compatible if connected as a footpod?

Any help is appreciated,

Brad_Olwin

@fluca said in Stryd Calibration Clarification:

@dimitrios-kanellopoulos Hello Dimitrios,

should this process work with STRYD v1 (HR strap version) connected as a footpod?
I tried yesterday but on the first run without auto-calibration I got speed approx 130 km/h and 25Km in about 8 minutes:
https://maps.suunto.com/move/ficheral/622488bf3776f1566320daf1

Second run with auto-calibration on did not improve:
https://maps.suunto.com/move/ficheral/622488c629c5c10fff6c48a5

Did I do something wrong or this hold version of STRYD is just not compatible if connected as a footpod?

Any help is appreciated,

It is compatible but I have found v1 of Stryd (the only one I own) to be short on trails. Having GPS calibration did not seem to help that so I typically only use Stryd as a power pod. On the treadmill using as a foot pod worked for me but this was a long time ago as I rarely ever use a treadmill.

Bulkan

@Brad_Olwin he is referring the previous version I think. The one was a chest strap. Not in the foot.

fluca

@bulkan thanks that’s correct. It is the HR strap version

Brad_Olwin

@fluca said in Stryd Calibration Clarification:

@bulkan thanks that’s correct. It is the HR strap version

Ah, I have that one too. Stryd is located near me. Their advice was not to continue using this one. The foot pod is far better. There were many issues attempting to get reproducible power on the Pioneer version. My understanding is this does not measure distance but I don’t clearly remember, that is why I thought you meant 1st foot pod version.

fluca

@brad_olwin Got it, thanks.