Wild disagreement between Garmin and Ridewithgps elevation: common problem?

[BumbleBeeDave]

I got my first Garmin--a used 800--at the start of this season. I've noticed the elevation from the Garmin for a particular route is almost always far more than what ridewithgps says it is for that route.

On this latest ride yesterday, the Garmin said 4426 feet, but my Ridewithgps map said 3776 feet.

Anybody else have this problem? Consistently? Is there any reference available to calibrate the Garmin? Is one of the other usually more accurate?

I don't want to be bragging I climbed Everest when I actually only climbed Rainier! ;)

BBD

[OtayBW]

I got my first Garmin--a used 800--at the start of this season. I've noticed the elevation from the Garmin for a particular route is almost always far more than what ridewithgps says it is for that route.

On this latest ride yesterday, the Garmin said 4426 feet, but my Ridewithgps map said 3776 feet.

Anybody else have this problem? Consistently? Is there any reference available to calibrate the Garmin? Is one of the other usually more accurate?

I don't want to be bragging I climbed Everest when I actually only climbed Rainier! ;)

BBDHAR! :rolleyes:
I've found the same wild disagreement between several Garmin units among folks on the same ride. You've got ~17% difference; it's not atypical to see at least 10% between Garmin units - even the identical Garmin units.

Maybe shoot the RWGPS guys note. They're pretty accommodating.

[Davist]

It may be because the Garmin's default is "barometric altimeter" and RWGPS uses topo data? I know there's always a discrepancy and only thing I can think of.

[dddd]

One of the Garmin programs on my computer gives a box to check if I want correction of barometric/altitude data, and the change in altitude readings is positively huge (over 25%).

Not sure what's going on there, if perhaps road data is being applied to my uploaded barometric data or what.

Result is that I consider the altitude gain/loss data meaningless.

My Garmin does always give the correct altitude of my home location FWIW.

[joosttx]

my Garmin is wildly off for elevations. Recently I did a 100 mile ride where the Garmin showed I climbed a little over 8400ft. When adjusted to topo maps or whatever it is, my ascent was around 14K. I watched my Garmin tick off 5ft on a 300ft climb.

[jb_11]

Try calibrating it:

https://support.garmin.com/en-US/?faq=sFMkjQFdnZ99DcunfAue66

[BumbleBeeDave]

I'll go look at this.

BBD

[unterhausen]

I'm pretty sure rwgps under-counts because they want to match Strava as best they can to avoid questions.

[Mr. Pink]

And MapMyRide, too. I have Garmin share my ride with both Ridewitgps and Mapmyride, and all three don't agree. But, of course, I just go with the higher number. Has to be the one.

[BumbleBeeDave]

has to be the one.

obviously!

;)

[NHAero]

I went through this with my iPad using RWGPS and then my Wahoo Elemnt. The Elemnt is using barometric readings, which can change for other reasons besides elevation, and I don't think the correction for temperature, if there is one, is good. I tend to accept the RWGPS elevation, which is lower when I switched to the Elemnt from the iPad, on the same rides. It's a mystery. Also, my MTB buddy has a Garmin, and we don't agree on elevation doing the same ride.
I don't understand why RWGPS can't figure elevation from the route and the topo map. If it is doing that, why did the elevation number drop once I switched from the iPad to the Elemnt?

[brucehappy]

Perhaps it prefers the data from the wahoo device over its own topo based calculations?

[fijichf]

I rode a known-to-us 50-miler with a bud on Saturday and his Garmin clocked us in at 112.65 miles...who knows. Putin must be playing with the satellites.

[Bob Ross]

fwiw I've never not seen a wild disagreement between Garmin and Ridewithgps elevation.

[djg21]

fwiw I've never not seen a wild disagreement between Garmin and Ridewithgps elevation.

Me neither on my current Edge 1030. I have it calibrated to the actual elevation in my driveway and it automatically recalibrated. It’s pretty accurate. I’m not sure the 800 is as accurate.

[Cat3roadracer]

Dave - some of these devices shut off when they do not detect speed, i.e. - you are going really slow. I've ridden with you more than once, I expect this to be the case.

[djg21]

Dave - some of these devices shut off when they do not detect speed, i.e. - you are going really slow. I've ridden with you more than once, I expect this to be the case.

Ouch!

[Mr. Pink]

Insult to injury when you're struggling up a wall and you hear that alert sound that says you're dead.

[verticaldoug]

I always thought ridewithgps and other mapping apps overcount because instead of using bridge height for crossing a valley, they sometimes use the valley floor.

https://ridewithgps.com/routes/32936215

map says you are crossing at sea level, but bridge road height is at 100 ft roughly for mario coumo bridge.

https://ridewithgps.com/routes/32936239

Bear Mountain Bridge , same thing, I descend 100 ft and climb 120 ft out

[marciero]

I always thought ridewithgps and other mapping apps overcount because instead of using bridge height for crossing a valley, they sometimes use the valley floor.

https://ridewithgps.com/routes/32936215

map says you are crossing at sea level, but bridge road height is at 100 ft roughly for mario coumo bridge.

https://ridewithgps.com/routes/32936239

Bear Mountain Bridge , same thing, I descend 100 ft and climb 120 ft out

Ha! I never considered that.

That would seem to account for some of the discrepancy. But my sense is that it has always been notoriously difficult to measure ascent accurately. Using barometric pressure has always struck me as a flimsy way to do this. It's surprising it works as well as a it does. And forget about raw elevation. Doesn't pressure vary daily? But even using satellite or topo data I am not even sure there is an agreed-upon way of calculating this. Perhaps someone here has GIS or cartographic expertise can chime in. My Garmin unit consistently records less than rwgps, which in turn is less than the "corrected" ascent, or elevation gain, on Strava (strava calls it elevation).

[NHAero]

Is Strava thought to be more accurate than RWGPS?

[BumbleBeeDave]

Dave - some of these devices shut off when they do not detect speed, i.e. - you are going really slow. I've ridden with you more than once, I expect this to be the case.

:cool:

[unterhausen]

Is Strava thought to be more accurate than RWGPS?

Strava definitely under-counts. As I said up-thread, some time back rwgps changed their algorithm to match strava better. So they should be pretty close. I'm pretty sure strava filters out smaller hills. So it might not really matter depending on the ride.

Last summer I rode with someone that had an 810 and there was a large discrepancy between the climbing he did and I did. I had an 800 at that time. Haven't compared since we both got 830s.

Barometric pressure works a lot better on short rides where external factors like storm fronts aren't as likely to affect the atmospheric pressure. I had one ride where my house was 200 feet different between leaving and coming home.

[NHAero]

I've seen the same.

snip
I had one ride where my house was 200 feet different between leaving and coming home.

[Web1111a]

What I tend to do is have it connect to the satellite and wait a couple of minutes

That seems to eliminate the difference between start and stop elevation

I think that may be caused by which satellite it grabs

The other thing I notice is that my elevation varies at start on different days