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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

    I see the same sort of inaccuracy during my latest triathlon, while my normal standalone bike GPS data looks good (not on the same course). I also used GPS/Glonass on firmware 2.80 in this race. A triathlon I did early july on firmware 2.50 with GPS/Glonass had normal GPS data on the bike. Strange...

  • 0 over 5 years ago

    Apparently this is happening to multiple people. See longer discussion (which I started) on slowtwitch

  • 0 over 5 years ago

    GPS Chip might be still programmed in water mode?

  • 0 over 5 years ago

    I just noted the same issue, I rode the same road with my 935 in bike mode and in tri-bike mode and I have two different tracks, one perfect and one...with cutting turns. I think it's only software issue, please Former Member have a look and solve for the next firmware. 945 is the best TRI watch, this could't happen!

  • 0 over 5 years ago

    This is a duathlon over the weekend. Two laps on the run, 4 laps on the bike, 2 laps on the run. My wife’s 945. Granted there were no challenges to the GPS but you can see the tracking is good. Even zooming in on the bike route the lines clearly follow the road and overlap each other. GPS+GLONASS 1 sec recording. 

    https://www.strava.com/activities/2729219466

    And an image

  • 0 over 5 years ago in reply to Dr Phil

    Ok,thx. The bike track has issues only in TRIATHLON mode and not in duathlon. When 945 starts in the water something happens!

  • 0 over 5 years ago in reply to micchei

    At least my duathlon clarifies that it is not 'multisport mode' ( as intimated in the OP) per se, but triathlon specifically.

    Looks like the problem might be related to getting a GPS fix then after coming out of the water. What were the swim tracks like?

  • 0 over 5 years ago in reply to Dr Phil

    I think it's only firmware issue, in the water and in the uphills the tracks are ok, the watch has problems in downhills or at high speed.

    The watch couldn't have the same procedure to analyze the gps signal: the distances and the speeds are different from water to roads and from uphills to downhills

  • 0 over 5 years ago in reply to Dr Phil

    My swim track of this particular race looks decently.

  • 0 over 5 years ago in reply to micchei

    tracks being OK uphill is just due to slower speeds and lower sampling rate/higher smoothing not being noticeable then.

    I think by now we have established the there must be some issue switching from swimming to cycling in TRIATHLON mode. Clearly a software issue and if I might say so (as a developer myself), this thread is serving a clear description of the issue on a silver platter for the devs to fix, so kindly get on with it. After all right now Of all the people in a race, I have by far the crappiest GPS track, whilst using what marketing tells me is the best triathlon watch there is....