Big discrepancy in climbing data VeloTrack, Isaac, Garmin

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the shovel
Posts: 31
Joined: Fri Sep 30, 2016 7:28 pm

Big discrepancy in climbing data VeloTrack, Isaac, Garmin

Post by the shovel » Thu Apr 12, 2018 3:46 pm

I don't expect identical climbing data from my Garmin Edge 1000 and my PowerPod readout in Isaac, but with the addition of VeloTrack on my iPhone, the discrepancy is too large for me to ignore.

On my most recent ride, my Garmin Edge 1000 said I'd climbed 730 meters, while my PowerPod reported it in Isaac as 627 meters. They aren't precision instruments, and I wouldn't write in to complain about a relatively small discrepancy like that. But the GPS Tracker feature, as reported in the VeloTrack app on my iPhone, lists the climb as 1272 meters. That's more than double the Isaac and nearly double the Garmin.

All three are set to record in metric. The Garmin is closest to the official climbs recorded for various rides, and for the elevation change noted on markers on the way up marked mountain roads that have no flat or downhill sections.

Any suggestions for what I may have set wrong in the VeloTrack?

As for the GPS Tracker, I love the Google Maps version of my route. It allows me to examine my power output on rides by exact location, which I find useful in spotting "lazy" sections where I need to work harder.

Thanks,

The Shovel

Velocomp
Velocomp CEO
Posts: 4921
Joined: Fri Jan 11, 2008 9:43 am

Re: Big discrepancy in climbing data VeloTrack, Isaac, Garmi

Post by Velocomp » Fri Apr 13, 2018 6:07 am

The purpose of VeloTrack is to provide accurate GPS data for Isaac. VeloTrack was not designed to provide accurate measurement of elevation gain. The app approximates elevation changes through GPS readings it receives.

Garmin uses GPS readings to know the current elevation (that's why its elevation readings agree closely with signs on the road), and baro sensor readings to record the elevation change (GPS is not so good at elevation change).

PowerPod has a baro sensor. It is quite good at measuring elevation changes, but it does not "know" the actual elevation, because barometric pressure changes with weather.

You should expect Garmin and PowerPod to give similar measurements of elevation gain.
John Hamann

the shovel
Posts: 31
Joined: Fri Sep 30, 2016 7:28 pm

Re: Big discrepancy in climbing data VeloTrack, Isaac, Garmin

Post by the shovel » Tue Apr 17, 2018 10:00 am

Thanks, I'll simply ignore the VeloTrack elevation. There's no need for it with Garmin and PowerPod providing readings. I had thought maybe it was a malfunction, but it's not a problem if VeloTrack isn't accurate for elevation. It's great for post-ride checking of power at specific points on a ride.

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