Strava

[xerxes]

I use the Strava app on my iPhone to record some of my rides. At the end of the ride, it gives a summary of the ride stats, which includes the amount of ascent. However, after uploading the ride and viewing it on my PC, the number of feet of ascent is reduced by about 10% (haven't calculated it exactly). Has anyone else noticed this?

[Jdsk]

Previous discussions of GPS devices and altitude, and errors:
viewtopic.php?p=1535353#p1535353
viewtopic.php?p=1543145&hilit=strava+altitude#p1543145

Jonathan

[xerxes]

Previous discussions of GPS devices and altitude, and errors:
viewtopic.php?p=1535353#p1535353
viewtopic.php?p=1543145&hilit=strava+altitude#p1543145

Jonathan

Thanks, that's interesting. I naively thought that the GPS signal alone would suffice to give the altitude at any given point, based on the time taken for the satellite signal to arrive.

[rareposter]

Previous discussions of GPS devices and altitude, and errors:
viewtopic.php?p=1535353#p1535353
viewtopic.php?p=1543145&hilit=strava+altitude#p1543145

Jonathan

Thanks, that's interesting. I naively thought that the GPS signal alone would suffice to give the altitude at any given point, based on the time taken for the satellite signal to arrive.

GPS isn't great for altitude. A lot of modern GPS head units have a barometric port, it's a lot more accurate for height. However, as linked above, Strava has billions of data points now plus accurate mapping worldwide so it'll auto-correct any glaring errors.

My head unit will pop up a notification at the start saying "elevation corrected for location" then "ready to navigate". The Strava phone app doesn't do that, it'll record, upload and wait for Strava's database to do the rest.

[eileithyia]

We have 3 different garmins all of which tell us we have each done different amounts of climbing...

[TrevA]

It’s called the Strava Tax!

Whenever I upload a ride, Strava always takes 0.1mph off the average speed, the so called Strava Tax. ( More likely a rounding algorithm that always rounds down).

[ChrisF]

It’s called the Strava Tax!

Whenever I upload a ride, Strava always takes 0.1mph off the average speed, the so called Strava Tax. ( More likely a rounding algorithm that always rounds down).

Not always! There seems to be a problem with my Wahoo which sometimes keeps on recording time while I'm stopped at a cafe etc, thus reducing my average quite a lot. Yesterday it had an average of about 16 kph which I knew was way too low; when I uploaded it, Strava magically changed it to nearly 20 kph

[mattsccm]

Can you not change the Wahoo recording? My Garmins have all shown be riding time and overall time. The only snag is that auto stop and start on fires up at 6mph and there are time when that isn't slow enough!