[Closed] Wahoo bolt elevation/temperature weirdness - RMA?

GPS altitude is always unreliable. It's looking at the intersection of the lines from the unit to the satellites, and for altitude the lines cross at quite a small angle, so small errors make a big difference. If the map has altitude information built in, it can take the altitude from the calculated position, which is more accurate. Don't know the details of the Bolt so don't know if it has that option.

The bolt has a barometer altimeter which is adjusted using GPS - https://support.wahoofitness.com/hc/en-us/articles/115000441324-Why-am-I-Seeing-Elevation-Differences-in-My-Ride-Data-

How does the ELEMNT calculate elevation?
The ELEMNT primarily calculates elevation data from a barometric altimeter which measures air pressure. While air pressure typically provides very accurate elevation measurements, it remains subject to factors like temperature and changing weather patterns. As with all barometric altimeters, environment changes can cause elevation readings to "drift," even when stationary or riding at on a level path.

To counter environmental elevation drift, barometric altimeters require regular adjustment. For this, the ELEMNT uses GPS.

Why doesn’t the ELEMNT primarily use GPS to calculate elevation?
GPS elevation is often unreliable due to GPS satellite positioning and coverage. In testing, we commonly found GPS elevation inaccuracies in hundreds of meters. Because of this, consistent and accurate elevation data is best achieved using GPS-adjusted barometric altimeter data.

How does the ELEMNT use GPS to adjust elevation?
When a ride starts, the ELEMNT calculates elevation using the barometric altimeter and compares it to the reported GPS elevation. If a discrepancy is found with the barometric altimeter elevation, the ELEMNT adjusts using GPS data. Before this is done however, the ELEMNT performs additional calculations to determine GPS elevation accuracy. If GPS elevation is deemed inaccurate, it is discarded and no adjustment is made. This prevents skewing elevation data with poor GPS data, but also means that certain situations may also prevent the ELEMNT from correcting barometric altimeter drift with GPS.

What situations impact elevation data most?
Since the ELEMNT uses GPS and barometric pressure to calculate elevation, these situations are likely to impact elevation readings:

Large changes in temperature or humidity like stepping outdoors in the summer from an air-conditioned environment
Riding in or near inclement weather like rain and snow
Riding near large bodies of water
Clogged or obstructed barometric altimeter ports

How do ELEMNT elevation readings compare with other GPS bike computers?
Using altimeter elevation and correcting drift with GPS data is the best way to provide consistent and accurate data. Some computers use either altimeter data or GPS data as the sole source of elevation data, despite the flaws in each of these outlined above.

On the rare occasion where barometric altimeter elevation drift cannot be corrected with GPS data, elevation accuracy may be skewed. However, these situations are unusual, occurring only when numerous environmental factors conspire with GPS signal issues. All devices calculating elevation with a barometric altimeter face these challenges.

By using multiple factors to calculate elevation, discrepancies can be resolved when the weather stabilizes or when accurate GPS data becomes available. This ensures the ELEMNT provides the most consistent and accurate elevation of any cycling computer currently available.

What can I do to improve elevation data?
Since the ELEMNT needs good a GPS signal to achieve maximum accuracy, starting a ride after gaining full line of sight to the sky and acquiring a solid GPS connection ensures the best results.

Pairing a speed sensor like the Wahoo Blue SC or RPM Speed to your ELEMNT can correct GPS inaccuracies and improve elevation and grade data when under tree/building cover or wherever GPS is unavailable.

You may also want to consider checking the barometric altimeter ports on your ELEMNT and other solutions offered in the ELEMNT Data Accuracy article.

Does it work like the element?

https://support.wahoofitness.com/hc/en-us/articles/115000441324

You know what, just looking at another few segments from September 2018 and then from 6 weeks ago, although the actual elevation is slightly off, the elevation gained and elevation profiles are identical - so I'm not going to worry. Temperature/riding close to/over water, who knows. The important thing is that my feet climbed is accurate which it looks to be!! 😀

I rarely look at the elevation when riding anyway, but was puzzled to see -150ft at one point, and me not riding in 20ft of water! 😀

My Lezyne Super GPS has the same issues, it takes a good 10+ minutes to see temp changes when I take the unit from indoors to out.

Similar elevation issues with the barometer and GPS algorithm, I always use the Strava correction facility on the ride headline page in top right corner. It changes less than it used to, but it can easily be 200+ feet of correction.

although the actual elevation is slightly off, the elevation gained and elevation profiles are identical

That makes absolute sense for a GPS calibrated barometer. The barometer measures accurately but has to be recalibrated as the weather changes and the GPS calibration is inaccurate.

Awesome, yeah that makes sense, just done the strava elevation correction on a couple of rides and they're much better.