GPX/FIT file comparison

If your Mac has an sd card slot, slap a card in there - put a Garmin folder on it and copy all the .img's from the watch to the folder. Basecamp will see them a lot quicker!

(Mac Mini owner here!)

No SD slot for me but I have a means of doing so. Keep meaning to try it. Just got used to using OS mapping for everything tbh. 

Works well and far quicker than waiting for them to index...!

Dr Phil said:

I think it’s speculation that Strava gets the GPX file.

Speculation, and it's wrong. Strava does get the .FIT file - you can even export it back verbatim

https://ibb.co/sCRSP8C

I've done a binary comparision with the GC original and the .FIT exported from Strava.

.FIT exported from Strava on the left, original from GC on the right

https://ibb.co/0t5SNs3

Dr Phil said:

If GC sends the GPX file to Strava why then do I rarely see any difference in distance?

Ɛpsilon said:

Like you I’m not seeing it. I think strava gets a FIT file but I’d happily be corrected there. I wonder if like me, you live in a well covered area for DEM

Strava import fit file and have an interesting function you could use to compare distance calculated during running and distance calculated after saving. 

The function is "correct distance". 

@AJR could you check if also in this way you have same distance difference than import in base camp? Probably this way is quicker ;) 

Anyway, I have the issue walking but not running. This could be reletad to differen speed but could be for another reason, running I use HRM-TRI with running dynamic, so cadence is calculated from strap data. 

So, in my opinion could be an internal accelerometer issue and how Fenix 6 auto calibrate it. I remember that also people running indoor had similar issues... 

People with Stryd or footpod usually does not have this issue and I think also people with running dynamics devices. 

I think could be good to investigate it. 

An interesting article about this topic:

support.strava.com/.../216919487-How-Distance-is-Calculated

I do but I get minimal distance differences in my run. I think partly perhaps because I run in quite wide open spaces perhaps.  What sort of percentage difference do you get? When I get home tonight I’ll test a few.

as I see quite different ascent/descents… I think they’re the cause of most of my issue here. And I suspect Strava does something similar. Will read the link now :)

Interesting.. it does indeed sound like what strava calls Ground Speed Distance is indeed discarding GPS elevation per data point, locking the altitude to the underlying map position and then calculating distance……

Just to be sure you have read it, I added a link from Strava website about this topic. 

5km run with HRM-TRI I have just 60/70 mt difference. Walking whithout HRM-TRI I have sometimes 400mt difference on 2,5km total distance, always more that 100 mt in 2/2,5km distance. 

I have not pace issue during running, I this also this is because I use an HRM-TRI. 

Yeah. They also talk about discarding data points as well, which suggests you can sort of ask strava to be a bit more aggressive in its data checks. But the Ground Based Distance thing does seem like they link height to the underlying map. So it does indeed sound like in that case when you click the ? Under elevation on your activity, they do that there. And then when you click the ? Next to distance they do some aggressive data smoothing of their own algorithm…..