HR Dynamic Source Switching - what is the point?

Interesting.

I am still on 18.27, as the newer firmware unfortunately has not been offered to me until now (using Garmin Express twice also did not help - guess they take it seriously now with phased rollout).
Had a bike ride today and as you know from the other thread, I also have my 955 on the handlebar then. Also use the HRM Dual for biking. Even though with 18.27 the optical HRM stays on during runs at least, even if you use HRM strap, while having it on the handlebar it seems to have no negative effect. All the HRM readings were plausible and changed according to my effort.

But good to know I will really have to take care of that with the upcoming release and turn the dynamic source switching to off. (I planned to do that anyway because I don't get the benefit and for all training I use HRM strap, just walking/hiking/etc. the optical one)

Thanks for the hint.

Yes, with previous firmware I used it the same way and never had any problems. But well, before I didn't have the Source Switching option either. Anyway, I don't know this precisely, I guess, but it's good to look at it since it's the first time I use the new firmware with that option. Good move by Garmin that already suggests that our next HRM will be one of the suggested ones that cost 40% at least...

soptunna said:

I, with a Polar H10, am just glad that they finally provided a switch to turn the thing off. The last couple of firmwares have probably suffered needlessly from Garmin OHR/Strap experiments.

My experience exactly. For a few weeks without the option to turn that thing off, the first 10-20mn of activities with my HRM-Pro + gave me willy erratic data which tanked my performance condition and maybe my VO2 Max estimates.

I switched to the polar H10 and the problem disappeared.

After Garmin provided the option to turn it off, I did so. The HRM Pro+ is now back to being reliable.

When you had those erratic readings, did you check whether it was because the watch switched to wrist HR (which was wrong), or did dynamic switching somehow mess up strap hr?

I didn't check. I thought it was the strap being dry or something, despite wetting it beforehand. I tried gel also.

I guess the watch switched to OHR which was wrong, since the chest strap was working fine when using Flocsy's CIQ second strap comparison app.

Yes, I assume the same. The watch switch to OHR, and in my case, as I have it on the handlebar of the bike, it gives wrong values. I believe this because the times I went out riding with wrongly Airplane Mode on, the HR values were wrong as well.

It would be still possible to check what happened, since since the fit file now contains wrist hr, strap hr, and the hr selected by the algorithm. It would be interesting to see those in FitFileViewer's graph.

And yes, watch on the handlebar is a good example of when dynamic switching should definitely be off (now that Garmin finally gave us the choice).

I learned that now the FIT shows both the wrist HR and the external HR, thank you.

Unfortunately, when the HR went bad, I stopped the activity and restarted it. I checked my fit files for the runs around the time frame and couldn't find one with absurd HR readings during warm-up.

BittiEtupes25 just out of curiosity: what is the name of the FIT field and subgroup where you store which HRM you are using? Thanks a lot!

This is a partial view of what FitFileViewer can display. To the left, the HR retained, to the right, the writs HR and the external HR data.