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[Bug 14.20] Stryd incorrectly auto-calibrated by HRM

Sesse__
over 2 years ago

Hi,

I have a 955 Solar, a Stryd and a HRM Pro+ (the latter is just a few days old; I lost my older HRM). Firmware is 14.20.

I have Stryd auto-calibration _off_, but I've manually set it to 101.0 after measurement on a track. I use speed/distance from Stryd “always” (not just indoors). Today, I had a run with no GPS (chose normal outdoor running profile, but it was on an indoor track and the GPS didn't lock) and the displayed speed felt just way too low compared to my fatigue. I assumed this was because I had a really bad day, and aborted the run halfway.

This was the first track run with my HRM-Pro+, and I couldn't change its speed/distance settings on the watch because it said “Footpod connected”.

Afterwards, I figured out the speed just _was_ too low. Something had changed the calibration factor of my Stryd to 95.6! This has never happened before, and I know of no good reason why it would. The only thing I can imagine is that the watch wrongly calibrated the Stryd using the wrong data from the HRM-Pro+. I also verified that this is completely wrong by just jogging 400m on the track, which came out at 378m.

Help :-)

  • 0 over 2 years ago

    Addendum: I cross-checked against a similar run (same place, same watch, same shoes, similar intensity, but with HRM-Tri instead of HRM-Pro+) a week ago, and the distance/speed was accurate (within 1% of the raw Stryd data). So this is a new problem.

  • 0 over 2 years ago

    Do you have the HRM setting set as GPS and Pace indoor only ?

    not sure if this would impact  this as I don’t use Stryd .

  • 0 over 2 years ago in reply to S.M.R.

    As long as the Stryd is also connected, I cannot access that menu at all (it just says “footpod connected” and refuses me access). After the run, I took the Stryd deliberately out of radio reach of the watch, and then I could access the menu item for the HRM; it was set to pace/distance indoor only, which I believe is the default (and I've now set it to “never”).

    I would assume it used the speed/distance of the Stryd, but I also believe it (wrongly) calibrated the Stryd using the HRM's data, which _essentially_ means that it used the speed/distance of the HRM. This is just a guess, though. It could also in theory have calibrated the Stryd using GPS data from another activity yesterday, but that would also be a bug (just a different one), since the Stryd is set to calibrate never.

  • 0 over 2 years ago in reply to Sesse__

    Ok, the joys! Good Luck

  • 0 over 2 years ago in reply to Sesse__

    I have similar issue, but I don't think it has something to do with HRM itself. I have HRM Pro +, no calibration set for Stryd (defalt value 100). In some runs I had reverse issue, pace was too fast because Stryd registers longer distance as really passed. I know this, because I'm runnng mostly on the track. What helps in my case is to manually connect Stryd in Sensors&Accessories menu immediately before starting running activity. So don't leave Stryd to auto connect after starting running activity.

  • Former Member
    0 Former Member over 2 years ago in reply to Sesse__
    [deleted]
  • 0 over 2 years ago in reply to Former Member

    I figured out what was going on: My Stryd had been reset to auto-calibration ON. I don't know what did this (it definitely wasn't me :-) ), but I would guess it's a firmware update resetting it at some point (I'm in the beta program). I'll see if I can go through the .fit files and see if I can figure out when it happened, because I think the calibration factor is stored there somewhere.