Discrepancies between GPS readings/devices...

HJCsDaddy

So, my fellow fitness freaks, I have a conundrum. It seems my Forerunner 305 and my MapMyTri GPS systems are reading different distances for my runs. On the shorter runs, it's not too big of a concern, but as the distances grow, obviously the gap grows. It seems my MapMyTri app on my iPhone says I run farther than my Forerunner. Any advice??? Thanks!

twinmom_112002

From all my readings....I would trust your garmin more than the app on your iphone. The iphone picks up and loses gps more than the garmin. When the iphone loses and picks up it just draws the shortest line between the two points.

BrianSharpe

I seem to recall that the Garmins are supposed to be accurate to within a few metres (when I save my runs to Google Earth I can usually even see which side of the path I've been running on with my out and back longer runs). I've never used the GPS in my crackberry except for mapping destinations.

HJCsDaddy

Awesome advice on Google Earth thing. I will do that this weekend after the 30k.

aspenwind

No phone that I've ever seen holds GPS signal as well as a dedicated GPS unit does.

The result is that your position bounces around with the phone and adds distance because it thinks you went 10ft to this side then 30ft the other way over and over.

stingrayinfl

Go with your Forerunner. It is very accurate

scottb81

There will be some error with any GPS but there should be less error with the Garmin.

BrianSharpe

Awesome advice on Google Earth thing. I will do that this weekend after the 30k.

In the Garmin Training Center one of your options is to view the activity in Google Earth, here's an example from an 8km run earlier in April.....



Have fun on the 30k!