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Mileage seems to be off

Former Member over 8 years ago

Just made the switch to Garmin and I am loving it so far. However my mileage seems to come out less than I expect. I have several courses and after running them, the tracked mileage is less than what I got when I created the course.

Any suggestions would be greatly appreciated.

0 R_Tellis over 8 years ago

How did you come up with the mileage you're comparing your Garmin results to and how great is the difference?

If you used something like runningahead or the course builder in Garmin Connect then, as something that's map based, those aren't necessarily going to be the same as what you'd run or walk in real life.

If the difference is only 1%-2% that's not really enough to be concerned about.

0 Former Member over 8 years ago

Using the mapping program within Connect. It is also the same as with MMR. Looks like MMR was giving me more mileage than I deserved I guess.

0 Former Member over 8 years ago

Hello Barmach,

Sometimes the GPS can be way off if you are running near tall buildings or heavy tree cover. Zoom up on your track and see if it does weird things like go thru buildings or off across a lake :p

0 scooterv45 over 8 years ago

You also have to consider the Auto Start/Stop

Because it's been my experience that the auto start can be a bit slow to respond, as in you may have to move as much a 50 feet before the activity that has been paused resumes.

0 R_Tellis over 8 years ago

Using the mapping program within Connect. It is also the same as with MMR. Looks like MMR was giving me more mileage than I deserved I guess.

You haven't said how big the difference you're seeing is. Is it less than 100 meters or is it a couple of 100 meters? If it's the former I wouldn't worry about it, but if it's more like a half km then you might have to look at what's going on.

Unless you go out and ride the course with a bike which has a calibrated odometer you don't know what the actual distance of you routes are. If you were using MMR with a phone that has a good GPS chip in it those results are valid just as those from your watch are. Again this is assuming the difference is small.

0 Former Member over 8 years ago

So I had always used MMR via my iPhone. So far I have taken two runs with my Forerunner 235. MMR-6.22 miles; FR235 6.16 miles. MMR 5.04; FR 4.95.

0 chunkywizard over 8 years ago

That's just GPS variance in my opinion

CW

0 Dr Phil over 8 years ago

And what makes you believe MMR is accurate? Anyway, as noted the difference is insignificant. Far better to comment on the distance recorded between successive runs on the the same course using the same device. Even you will see variance.

0 caferey over 8 years ago

Make sure you've got a good GPS lock before starting. If possible wait a minute or so before you start running.

Best way to really check if the lock is good is to look at the elevation field and wait till the number settles.