GPS height discrepancy

[OldBull]

Hi all.

 

I'm using a Lezyne gps and started noticing that the heignt gained does not seem to be correct. The othet day my gps recorded a 284m gain, but my cycling computer and Google Earth indicates about 110m.

 

It was my impression that Lezyne is a bery good and accurate gps.

 

Is there a setting tnat mignt be wrong or am I doing something stupid?

[dirtypot]

I use a Lezyne GPS and find the barometer to be extremely accurate.  

Can't say why you're getting incorrect readings though.

[BigTom]

I did the Wartburg BP intermediate race last weekend - virtually every other racer I've seen on Strava has the elevation gain around 460-470m.  Mine is 365m.  And no, I didn't skip a hill.  My route profile looks just like the others. (I'm using a Garmin Edge 500)

[LeoKnight]

I did the Wartburg BP intermediate race last weekend - virtually every other racer I've seen on Strava has the elevation gain around 460-470m.  Mine is 365m.  And no, I didn't skip a hill.  My route profile looks just like the others. (I'm using a Garmin Edge 500)

 

Also using a Edge 500 and also get sometimes significant differences

[Guest]

I use the Lezyne GPS. It used to match Strava elevation but that has now changed. A few guys with other types of units have commented on the same thing so I think it is strava changing the value.

[BigTom]

Also using a Edge 500 and also get sometimes significant differences

If it is going to be wrong, why can't it at least ADD 100m?

[BigTom]

I use the Lezyne GPS. It used to match Strava elevation but that has now changed. A few guys with other types of units have commented on the same thing so I think it is strava changing the value.

My Garmin Connect and Strava values match in this case, so at least in mine it is not Strava changing the value.  Although I am aware of Strava sometimes using two sets of information to calculate a third, which may or may not be accurate.

[Skinnyone]

GPS will always vary, this is a common thing - because the satellites could be used to launch a strike against a target like a government house etc they are always altering the accuracy of the measurements so that if someone where to target something then chances are the missile/drone etc would miss.

 

I have seen variances of up to a 10m radius in any given plane...

[Bateleur1]

Strava most defintely is not the benchmark in accuracy when it comes to height recordings.  From what I understand is that Strava works of the mapping and does not take into consideration the actuall altitude of the road you are using.  Example: if you cycle a straight road that crosses a river.  You actually travelled on a straight road with no elevation, but Strava things you drove down the ditch through the river and back up the other side.  Hence the difference. Barometric would be more accurate.  I think Garmin takes the altitude of the road into consideration (I think) and therefor would also be more accurate.

[lechatnoir]

Try doing the track in Google Earth. It can be a bit iffy at times but generally is OK. It uses SRTM data for its DTM and is more accurate than Strava.

 

Not sure if you have enabled GLONASS on your GPS, but do so if you can.

 

FWIW, a mate of mine ran from Hout Bay to Noordhoek and back using Strava and was stoked with the 1500m elevation gain reported. The highest point is 160m, making 320 with a few bits and bobs along the way. A FAAAR cry from 1500m

[LeoKnight]

It is also possible on Garmin Connect to use the elevation correct settings,  but agree on a previous point, for road I suspect the total ascent will be more accurate than on MTB, where a 2 / 3 meter deviation from your actual position could be a material difference in altitude.  

 

Which brings up another questions.. the amount of times when the route profile indicated that the total climb is 800m for day 2, and your garmin tells you you have reached that level before the end and then you add another 200m till the finish.  

[LeoKnight]

Also with strava remember to switch off power saving, as it could impact on the freq of the gps recording points

[LBKloppers]

Hi all.

 

I'm using a Lezyne gps and started noticing that the heignt gained does not seem to be correct. The othet day my gps recorded a 284m gain, but my cycling computer and Google Earth indicates about 110m.

 

It was my impression that Lezyne is a bery good and accurate gps.

 

Is there a setting tnat mignt be wrong or am I doing something stupid?

A couple of years back I bought a Edge500 and used it in Madagascar. I often cycled below sea level and I took this up with the manufacturers. They did not want to admit to it, but I eventually got one of them to answer that the real matter is that GPS can with accuracy determine your true elevation, but GPS is controlled by the US Airforce and Glosnast by the Russian equivalent. Both these guys are afraid somebody uses a small devise like our cycling GPSes to guide something explosive towards their own shores. The solution Garmin came out with was the accurate sensors conforming to and bettering the aircraft industry - in short the barometric solution. If your cycling trip occur during changing weather patterns, the elevation will change. How much depends on how long you cycle and how severe the weather is changing.

I learned to live with this irritation.

[OldBull]

If it is going to be wrong, why can't it at least ADD 100m?

My results change by a bit more than 100m.

[OldBull]

GPS will always vary, this is a common thing - because the satellites could be used to launch a strike against a target like a government house etc they are always altering the accuracy of the measurements so that if someone where to target something then chances are the missile/drone etc would miss.

 

I have seen variances of up to a 10m radius in any given plane...

agreed, but about 100m is a bit rough