Garmin strap power + Stryd power = doubled power values in activity

That sounds like an issue you should raise with Stryd support. It may or may not be Stryd's "fault", but they need to know about the issue.

Just speculating, but I can guess at 2 possible explanations:

1) The same issue would've happened with older watches and the Garmin CIQ Run Power field, but nobody uses that with Stryd so it's a non-issue

2) With native running power support, Garmin is writing to the *native* Power FIT field, which the CIQ app could not do, and this is causing the issue with Stryd. (CIQ apps, even those written by Garmin, can't write to native FIT fields -- they can only write to developer fields, and optionally provide a hint that a developer field is supposed to "override" the native field. This hint is not even respected by Garmin Connect, tho.)

EDIT: I would also contact Garmin Support, as well.

[email protected]

Here is an answer from Stryd Support:

"Hello Piotr,

Thank you for contacting Stryd Customer Support.

Our current logic is only use IQ power if the normal power field is not available. We can make the change to default to IQ power for Garmin runs, but that takes some time. For now, I would suggest not using Garmin Power. I went ahead and scaled your run down to more normal values for the run.

Let me know if you have any other questions.

Best,
-Tim
Stryd, Inc.
Self-serve resources: stryd.com/support"

So my question is: is there any option to disable Garmin Native Power? My any idea is to not to use Garmin strap :(

Haha...typical Stryd answer, i.e. "do it our way or the highway" !

So I guess you're stuck with using wrist HR or a third party strap ?

In my experience it is because Garmin is writing power into the native power field in the activity FIT file. It thus appears in my Strava feed as well. I think Polar & Coros may do as well although can't be sure as don't have a device from either. As such Stryd is reading your FIT file and sees "power" where it ought to be.

Polar and Coros do the sensible thing and don't do their own power when a Stryd (and maybe other power meters?) is connected, so you don't end up with a problem. Garmin either needed to do the same thing or just have the option to disable the native support at least.

Luckily I use a polar HR and a RD pod with my Stryd so I can just not use the RD for now, some people just won't have that option though and end up with a mess really. (I've got a 255 but it's the same on there just to point out) 

Hello

i did a workout today using Stryd and RD pod from Garmin and I can see the Garmin power sent to Stryd app on my iPhone. Garmin power reads a bit higher than Stryd, that’s how I knew. 
I can see both power data sent to Garmin connect. 

I'm having similar issues. But the problem only shows up on Garmin connect and Strava.

When I look at my trainingpeaks activity it only shows stryd power (thankfully).

Ah the styrd power... Change your weight of your want but don't change it. Bit of a joke strus power. No comment on Garmin power yet but stryd is not self-consistent

Hi All,
it seems that an issues was resolved yesterday:

"Hello Piotr,
Thank you for contacting Stryd Customer Support.
I believe it's okay to use your HRM strap from Garmin. Let me know if you notice anything on the next run, but I believe they have corrected the issue now.
Cheers,