How does Strava know the incline grade pct. of various roads?
 

Is this some public GIS based topographic geo database they overlay your GPS location over?

I used to think it was done by known elevations at certain geographic points. But I think it more likely it is done by smoke and mirrors.

Thinking the secret ban has expired.

Yep, hitting it hard again. Disappointing....

I read that 3 times and now I have to take 3 ibuprofen.

They use data from the chips implanted in house cats.

They use a mix of sources, including public topo datasets.

https://support.strava.com/hc/en-us/...-Your-Activity

If the cat gets outside and climbs a tree the reading will be way off !

Strava doesn’t know. The GPS (receiver and software in your phone) resolves your elevation. The Strava app uses that GPS data and applies it to the various aspects of the app. GPS can resolve your vertical position the same way it resolves your horizontal position. It uses timing signals between the GPS satellites and your GPS receiver device down to the nanosecond (One nanosecond is to one second as one second is to 31.71 years.). When you go up or down a hill, that timing signal gets longer or shorter. When it detects that, it goes one step further and does the math to determine the degree of inclination, or percent grade.

Dan

actually, strava doesn’t use GPS elevation if it can be avoided given how very inaccurate it is. if you read the link above you’ll see they first use barometric altimeter data, and if you “correct” it they use an elevation basemap which was made from that same data, crowdsourced, and then they fall back to public elevation maps/models. if the GPS position is off of course the elevation correlation will be off too.

I can't fathom there is topo data that is so granular that some agency or entity actually recorded incline of every neighborhood street in USA

If this is the case, there must be simple altimeter apps out there.
I am going to test out this feature of the phone on my next walk

ftfy

That’s exactly what Google Maps began creating back in the early 2000s. Apparently Strava now has their own database of elevations that you and I helped create.

Most of your answers about Strava-provided elevation can be answered at this link: https://support.strava.com/hc/en-us/...-Your-Activity

Dan

It may well be that you can't fathom it. That doesn't mean it isn't real. If you work with RideWithGPS to map and record routes, they have all that elevation data built in. They use Google Maps and OpenStreetMap as two of the choices in their map data, but their elevation profiles come from Google Maps, which shows the elevation changes in detail. That data is there before you ever get on the bike, so no need for either barometer or GPS input. It's one thing to ask questions because you don't know or don't understand, but it's another to be wrong and yet be sure you are right.

https://www.usgs.gov/faqs/what-types...can-i-download

there are several sources for this data, but the one i’ve most commonly used is the national elevation dataset, which is free. it covers (at varying resolutions) the entire surface of the country. all you need is that and the coordinates of two points on a road to determine the slope between them.

google uses this data (as well as many other similar datasets) for maps/earth/earth engine etc.

I should have kept my original Strava record from the Five Boro Bike tour, it showed a vertical, 100% grade, 1200 foot change in elevation in lower Manhattan.

I used Strava's fix tool to remove the levitation. Strava got the original data from my GPS bike computer, so the GPS signal probably was bouncing off the buildings.

How did Google Maps create the topo data? Were there altimeters in the car? That is very cool.
I was in a private parking lot today, and Strava knew the % grade. No way that is in public topo data, but it has been driven by Google Maps!

the public (USGS) data comes from satellite and aerial measurements. it includes the entire surface of the earth, including private parking lots.

Why are you always so sure about things that you don't know and are obviously wrong?

especially funny when the link by which one can download said data, for free, is just a few posts above LOL.