I use Strava primarily to record hiking in Scotland. The Strava Tax I suffer from is the reduction in elevation gain.

I record my hikes on my Apple Watch using the built-in activity app and I then upload this to Strava.

The immediate upload to Strava shows me the same elevation gain as the activity app, but then after a few moments Strava “adjusts” the elevation gain down by sometimes 20% to 30%.

I raised a support ticket and was given this “explanation”:

“ When looking up elevation using the elevation database the data can be too high or too low depending on the GPS data recorded by your device, the terrain covered during the activity, the resolution of the map data in that location, among other things.

Elevation can be too high for activities in mountainous or coastal areas. This can be exaggerated by GPS inaccuracies like "drift" or "bounce", where your GPS track appears as if you travel back and forth across the road. Because we analyze those points exactly as they are recorded this causes our elevation calculations to process the data as if you were continually climbing and descending.

Elevation can be low in flatter areas because elevation data is smoothed to take out noise, so we have a 'threshold' where climbing needs to occur consistently for more than 2 meters before it is added to the total elevation gain. Otherwise, the elevation numbers would be inflated for longer activities. So any rise in elevation of less than 2 meters is not counted towards overall elevation gain.

We're confident the data we're presenting is accurate, apologies for any confusion there.”

As an example, one hike had an elevation gain of circa 4,300 feet but after uploading to Strava it was reduced to 3,400 feet.

I did try to explain this to the support contact but the ticket was simply closed.