Fenix 5 Pace Question

You can manually calibrate the footpod using a track or some other known distance. See this for an example: http://www.runsforcookies.com/2014/10/calibrating-foot-pod-to-garmin.html

...That got me to thinking. If foot pod calibration comes from GPS speed, and the GPS speed on my Fenix 5 sucks (which it does), how can the foot pod calibration be reliable?...

I had pretty much the same thought regarding the speed/cadence sensors on my bike. Instead of letting me enter my wheel size, which is known and fixed, it "figured it out" automatically using (I presume) GPS. Seems like it would be WAY more error prone that way... and for no reason (since entering the wheel size would only need to be done once and shouldn't take more than a couple seconds.

If foot pod calibration comes from GPS speed, and the GPS speed on my Fenix 5 sucks (which it does), how can the foot pod calibration be reliable?

Actually, it doesn't come from GPS speed. It comes from GPS distance. There's a big difference between the two. The Fenix 5 is decent at GPS distance. No matter what GPS you use for pace you'll have issues (a foot pod will always be better). The thing is there is a lot of things going on underneath the hood to 'predict' your current pace. The biggest problems these fitness trackers have is with detecting acceleration. When you accelerate at a fast pace, the computer (in your watch) initially believes it's bad data and waits for the next GPS information. From there it slowly, will give it to you as more data comes in. It behave the same way when you go from running fast to a walk.

Keep in mind most of the people here are Garmin Kool-Aid drinkers and will never admit to these flaws or even more pathetic have never even noticed.