Specialized iPhone App Shows Wrong Elevation Gain.

[RGOLD]

I don't understand why the iPhone app shows wrong elevation gain compare to the bike display. I attached some photos comparing elevation gain numbers for the same ride.

I texted Specialized US support number (313-468-7347) on Aug 27 regarding this issue but never got a reply back...

 

[Stefan Mikes]

The elevation gain as measured by either the e-bike or a smartphone app will always be wrong, and often dramatically wrong.

I assume there is a barometric altimeter in your e-bike, and another in the phone. The e-bike altimeter feeds the information into Mastermind while the Specialized App in the Ride mode certainly uses the phone altimeter, here the discrepancy.

As I said elevation gain given by available barometric altimeters is usually wrong or very wrong. It is because the reference atmospheric pressure cannot be updated by the e-bike or smartphone. It works differently for an airplane: there, the ATC frequently updates the airline pilots with the QNH information; therefore aviation altimeters are very accurate (but only for the altitude of the aircraft above a given airport!) Not the case with the altimeters we use on our rides.

If you want to know the accurate elevation gain, please connect the Specialized App with Strava. In Strava, there is a button for "Adjust/Correct Elevation", and that will adjust the actual elevation gain to the map.

Hope that helps.

 

[mschwett]

as stefan notes, altitude readings of many mobile devices are not very good. who knows what the bike display uses, but in this case it appears to be much closer to reality than the app.

better cycling apps have some options for whether to use the altimeter, GPS, or a combination of those and mapping data to track elevation, but i don't think the specialized app has any choices.

your out and back route on Leif Erikson is around 1,100 feet of elevation per strava, and around 1,300 feet per rideWithGPS, both of which use USGS or other contour maps to determine elevation. it's likely apple workout/maps is using something similar (your 987 foot value) and the bike computer appears to have gotten it basically right.

the 2,451 foot value from specialized is simply completely wrong, indicating that they're likely using only altimeter or only gps, either of which is very very inaccurate. GPS elevation is horrible, and altimeter doesn't work if the air pressure goes up or down much during the ride. using the two together can give a decent result.