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735XT - GPS inaccurate on track

Former Member
Former Member over 6 years ago
Hey guys,

I am using the 735XT for several month now, and, beside ONE big issue, I am completely satisfied. I am part of a running team and on every wednesday we train intervalls on track. They differ from 100m to 5k. The issue now is that my 735XT doesnt track my intervalls accurate. On a track of 400m, sometimes the difference is at least 20m (max. 50m) which is not that small. Other athletes from my team who are also using garmin products do not have that big issues. Do you guys have any idea how to improve my GPS?

I am looking forward to reading your answers!

Best,
Michael
  • 0 over 6 years ago
    I have had 7 Garmins over the years. None of them were accurate on a track. So forget about that. My Garmin 305, which was a good watch overall, would alert for a mile at about 1500 meters. I also have a Garmin 735xt. It is normal for this device to measure short by as much as 2.5% on road runs, so an 8 mile run might show 7.80 miles instead. It is consistently short. I know because I know where the mile markers are, and I run the same courses repeatedly.
  • 0 over 6 years ago
    Keep in mind, that on a track you run in a relatively small "circle" when you consider that

    (a) the unit tracks - at best - once a second
    (b) even under decent conditions GPS has a HDOP (essential the position error on the horizontal plane) of a couple of meters

    This would probably a fun Monte Carlo coding project (could even be done in Excel): Figure out how many points are recorded on the "turns" if you run your pace and record them every second. Randomly drop these points with a normal error with sigma of 5m. Compare the actual, curved, distance to the distance when connecting these points by straight segments. I am pretty sure that you'll find quite some differences.

    A better distance approximation can usually be taken from a self calibrating foot pod such as a Stryd.
  • 0 over 6 years ago
    My 735XT GPS is also way off, but not in accuracy but in timing; every change in pace is only recorgnized in 15 seconds later or so. Anyone familiar with this type of problem?
  • Former Member
    0 Former Member over 5 years ago in reply to Frank53

    I have both issue, When running on road I usually get shorter distance than my wife (she has a fenix5 plus) up to 5/600 m on 10k) and the instant pace is somehow extremely slow reacting to pace change. Any idea how to address these issues?

  • 0 over 5 years ago

    I had the Garmin 910 before and the pace was much more accurate. It seems as the 735  sometimes jumps from 4:30 up to 4:50 min/km while running at constant speed.