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GPS accuracy worse in multisport bike

flogazo
over 5 years ago

Hi,

I see a significantly less accurate or smoothed GPS track in the bike-segment in a Triathlon compared to stand-alone bike.

Context:
I have GPS+GLONASS enabled in my normal bike-activity. My Triathlon-activity uses a different activity ("bike-tri") as it's second leg, (different screens etc) but that also has GPS+GLONASS enabled.

Attached is an immage with a comparison of the SAME road with some turns in normal bike-activity and within a triathlon. It looks significantly different.

On the bottom you see an overlay of mine (black) and 3 other people's tracks (4 laps each, powered by Strava fly-by).
My track is the only one that sucks. (The other people all use various Garmin devices also, but not the 945)

What's going on here?
BTW: This consistently happens in all my multisport* events but the inaccuracy is limited to the bike-portion as far as I can tell.

*Edit: This thread has meanwhile established that only TRIathlon-activities are effected and not e.g. duathlons

  • 0 over 5 years ago in reply to corboerman

    That’s some good news given the issues reported about swimming. Does look like there’s something going on with the switch from swim to bike that doesn’t happen from run to bike. 

  • 0 over 5 years ago in reply to Dr Phil

    I edited my OP to account for your find! Thx

  • 0 over 5 years ago in reply to flogazo

    Just to clarify something. Sampling rate is always 1Hz. Data recording from Smart to every second just changes the amount of data recorded. Now, with plenty of storage it’s as well to keep the data recording to 1s as that will give a better track on the map afterwards. 

    As you say, there’s an issue here in the transition from swim to bike that is not apparent in any other transition.

    Have you logged this with Garmin Support?

  • 0 over 5 years ago in reply to Dr Phil

    I have - with a link to this thread.
    But I doubt this reaches people who understand what's going on as they asked me to re-sync with Garmin Express, do a hard reset and if none of that helps: send in the HARDWARE!

    Not keen on sending them my watch (and not having it for a couple of days/weeks), when its obvious that they need to address this on software side.

  • Former Member
    0 Former Member over 5 years ago

    In a recent Triathlon although I can see a clear improvement in the swim GPS coming from a 735xt, the bike seems very off from the normal cycling activities accuracy. Is someone looking at it at Garmin? @Garmin-Blake

  • 0 over 3 years ago in reply to flogazo

    I see it's almost 2 years exactly since the last post, but giving this a try anyway:

    I have participated in two triathlons this summer and I am seeing the same issue (poor/smoothened GPS track on transitions, bike and run) with my Forerunner 745. For any other individual activity (swim, bike or run) or even bike+run the GPS data is ok. The issue only happens in triathlon mode. For the bike part of the races, my Edge 530 shows a much better track, while for the run I have recorded much better tracks on the same course as well when just using the watch to record a run activity.

    I looked at some activities from other athletes that have completed the same race, and any Forerunner 745 or 945 and Fenix 6 (Pro) is showing the issue, while for example the Edge 530 or Forerunner 735XT or 935 is not having any issue on the same course. I was badly surprised to read that this issue apparently has existed for 2 years already.

    Have you had any progress with your issue?

  • 0 over 3 years ago in reply to LMALBLAS

    For anyone having this issue. I took up this issue with Garmin Support and they were able to reproduce it. It is supposed to be fixed in this weeks' software updates. For the Forerunner 745 those are the version 6.20 software update and version 5.11 GPS software update.