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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 to calculate elevation. Generally, air pressure provides very accurate elevation measurements, but can be affected by local factors like temperature and changing weather patterns. As with all barometric altimeters, when the environment changes elevation can drift with it, even if stationary or riding at a constant elevation.

To counter environmental elevation drift, barometric altimeters require regular adjustment to ensure elevation data accuracy. The ELEMNT uses GPS elevation data to help perform these adjustments.


Why doesn’t the ELEMNT primarily use GPS to calculate elevation?

GPS elevation data can be unreliable depending on GPS satellite positioning. In testing, sometimes extended periods of GPS elevation inaccuracy were experienced in which recorded elevations measured hundreds of meters off of actual. In light of this, we've found that the best way to achieve consistent and accurate data is to use GPS-adjusted barometric altimeter data for elevation.


How does the ELEMNT use GPS to adjust elevation?

During a ride, the ELEMNT calculates elevation from air pressure using a 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 not used and no adjustment is made. While this prevents skewing elevation data with poor GPS data, it also means that, at certain times, the ELEMNT may be unable to correct barometric altimeter elevation drift using GPS.


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 these methods remaining invariably subject to the issues outlined above.

 

On the rare occasion where barometric altimeter elevation drift cannot be corrected with GPS data, elevation accuracy may be skewed. However, these  occurrences are unusual and only found where numerous environmental factors combine with GPS satellite issues. Additionally, all devices using a barometric altimeter for elevation face these same challenges. By using multiple factors to calculate elevation, the ELEMNT's elevation accuracy can be resolved when the environment stabilizes or when accurate GPS data is available. This ensures that the ELEMNT provides the most consistent and accurate data of any cycling computer currently on the market.

 

What situations impact elevation data most?

Since the ELEMNT primarily uses barometric pressure to calculate elevation, these situations are likely to impact elevation data 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

 

What can I do to improve elevation data?

Pairing a speed sensor like the Wahoo Blue SC or RPM Speed sensor to your ELEMNT can help to correct GPS inaccuracies to improve grade data, generally.

Please also consider the solutions offered in the ELEMNT Data Accuracy article.

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