[GMarshall85]

Sorry if this is old ground but it’s really annoying me!
I recently got a Garmin Edge 510 and have noticed it never seems to match other friends Garmin readings when we do the exact same routes. It’s thousands of feet of a difference and I’m not sure whether it’s my Garmin or the other peoples?

Anyone else noticed this? Any ideas how to check how accurate it is?

Thanks
Gary

Topic

[Daveyraveygravey]

From DC rainmaker – http:/

From DC rainmaker – http://www.dcrainmaker.com/2010/05/understanding-sport-device-gps.html

[arfa]

Was out this weekend doing
Was out this weekend doing hill repeats and as soon as it started to rain, the elevation stopped going up on my Garmin 800 (over the same hill loop). End result was a 2000 foot difference. Pretty poor really and one of the reasons why I use it less and less

[vonhelmet]

mrmo wrote:GPS can give

mrmo wrote:

GPS can give height but it is never very accurate.

GPS can give accurate height if you are using an assortment of satellites more or less above you. However, for cycling (and indeed driving) people are generally much more concerned with position (and speed), which is much more accurately measured by satellites closer to the horizon, so our GPS units are programmed to look for and use satellites in those positions.

[mrmo]

It works on air pressure, it
It works on air pressure, it needs to know the altitude to associate with the pressure as is. GPS can give height but it is never very accurate.

[DEROSA1976]

I have found that if you add
I have found that if you add a couple of elevation points into the unit, it gennerally gives a more accurate figure, I set my home and top of a local hill.

[GMarshall85]

Now have 5 different people
Now have 5 different people with Garmins who did exact same route on Sunday and all 5 climbing elevations are different. Ranging from 2900 ft to 4700ft. So it’s not even a close range. Really annoying when you think of the money these things cost.

[kwi]

My barometer (Edge 705) froze
My barometer (Edge 705) froze one evening, climbed a mountain in a blizzard, Garmin recorded 7′ of climbing. 😕
This was corrected on upload though.

[Goyt]

Thanks Ianrobo, it’s on the
Thanks Ianrobo, it’s on the activities page for those looking for the setting.

[Al__S]

my 510 can be pretty screwy
my 510 can be pretty screwy with elevation too. Sometimes the uncorrected data will show me going up or down a cliff several hundred metres high. most odd when I’ve been riding in the fens.

[ianrobo]

on Garmin connect. I find the
on Garmin connect. I find the elevation correction strange. The last time I used it, it halved the height but when I planned the same route it was within 10% of the route on the garmin.

[Goyt]

Is that a setting on the
Is that a setting on the device, garmin connect or stava?

[Flying Scot]

Auto correct on upload will
Auto correct on upload will get it closer.

[Colin Peyresourde]

It works on air pressure most
It works on air pressure most of the time and so you’ll get deviations as a result of changes in the wind (was one of you wheel sucking more than the other?). I think it also uses a correlate off the satellites, but they can be pretty unreliable especially up a mountain.

I think that there is an auto-correct when you upload it to Garmin connect, or at least there used to be.

Also, if you have a route planned which has the altitude plotted that will help correct some of the altitude issues too – the computer uses an algorithm to calculate the altitude based on the air pressure and other factors, which if you are working on a mountain and you have high wind it can cause massive fluctuations.

[Author]

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