Comments on: I ran with a garmin 305 forerunner, would a hill make a difference in the distance? http://www.thegpsbuyingguide.com/584/i-ran-with-a-garmin-305-forerunner-would-a-hill-make-a-difference-in-the-distance/ GPS Reviews and Ratings Tue, 20 Apr 2010 02:59:20 +0000 hourly 1 http://wordpress.org/?v=5010 By: David A http://www.thegpsbuyingguide.com/584/i-ran-with-a-garmin-305-forerunner-would-a-hill-make-a-difference-in-the-distance/comment-page-1/#comment-640 David A Wed, 06 May 2009 05:58:33 +0000 http://www.thegpsbuyingguide.com/584/i-ran-with-a-garmin-305-forerunner-would-a-hill-make-a-difference-in-the-distance/#comment-640 I just read somewhere the other day (runners world?) that a 3 mile run that climbs 500 feet will only be off by 8 ft. the way that a garmin measures the distance according to the Pythagorean theorem. That being said, I would tend to trust the garmin over google or yahoo. I just read somewhere the other day (runners world?) that a 3 mile run that climbs 500 feet will only be off by 8 ft. the way that a garmin measures the distance according to the Pythagorean theorem. That being said, I would tend to trust the garmin over google or yahoo.

]]> By: J M http://www.thegpsbuyingguide.com/584/i-ran-with-a-garmin-305-forerunner-would-a-hill-make-a-difference-in-the-distance/comment-page-1/#comment-639 J M Sun, 03 May 2009 11:32:15 +0000 http://www.thegpsbuyingguide.com/584/i-ran-with-a-garmin-305-forerunner-would-a-hill-make-a-difference-in-the-distance/#comment-639 Supposedly the Garmin doesn't take elevation change into account with its distance calculations. However, most significant elevation changes (aka hills) would only tend to add a few feet in distance per mile compared to flat ground, and that usually remains within the several feet margin of error the unit has anyway. I would trust the Garmin over something like Google maps, but I would trust the Garmin more if you downloaded the data into the SportTracks software and used the elevation correction plugin with it. Also be aware that the measured distance is going to vary slightly depending on the degree of data smoothing you have set on the Garmin or in the software you download into. Indeed, that may account entirely for the varied distance you're getting regardless of elevation. (And unless you're zig-zagging around a lot, you probably need some degree of smoothing even though it's likely to result in a slightly shorter distance measurement, and thus a slower time.) Supposedly the Garmin doesn’t take elevation change into account with its distance calculations. However, most significant elevation changes (aka hills) would only tend to add a few feet in distance per mile compared to flat ground, and that usually remains within the several feet margin of error the unit has anyway.

I would trust the Garmin over something like Google maps, but I would trust the Garmin more if you downloaded the data into the SportTracks software and used the elevation correction plugin with it.

Also be aware that the measured distance is going to vary slightly depending on the degree of data smoothing you have set on the Garmin or in the software you download into. Indeed, that may account entirely for the varied distance you’re getting regardless of elevation. (And unless you’re zig-zagging around a lot, you probably need some degree of smoothing even though it’s likely to result in a slightly shorter distance measurement, and thus a slower time.)

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