The Zones of your 80/20 datafield do not match the Zones from the 80/20 website
If you have a close look to the table from the 80/20 website, you will see that the zones overlap each other. I.e. Zone 1 ends at 81% and starts at 81%. So running at 81% LTHR can be either Zone 1 or Zone2. This is not specified precisely and personally I don't think it is important at all, because the key idea is to stay in between a specified Zones and not at the border to another zone (which is very difficult to do anyways). There are some workouts you can do "harder" or more "easily", i.e. run at low Zone 2 or at high Zone 2. But as Zone 2 range is quite large, there is no issue here. But scratching the lowest or highest values on the other hand won't be correct. This is also what Zones X and Y are used for. When reaching those, they give a clear indication that you are really "too high" or "too low" now.
Anyhow, for the app/data field we needed a more precise solution as the app can only compare exact numbers. It can't say "hey, you're in Zone 1 and maybe also Zone 2!". It can only say either this or that. So to solve this, I decided to begin each higher zone at one percent higher than the lower zone. If needed please use these numbers in Garmin to have a perfect match between 80/20 app and Garmin zones.
72% <= Z1 <= 81%
82% <= Z2 <= 90%
91% <= ZX <= 94% ( <- Zone X is made a little bit smaller, but its quite hard to define this zone anyway. It's just an indicator that you're training too high for Zone 2 or too low for Zone 3 effort.)
95% <= ZX <= 100%
101% <= ZX <= 102%
(yes, Zone Y is very small, but again this is even more unimportant than zone X. It's just some sort of indicator that you might be not high enough or too high already. The essence is that when you're going over 100% LTHR usually you're already too high. when training in Zone 3 try to stay in the middle of Z3 or close to 100, but never higher! When doing hard intervalls on the other hand, these need to be hard and not close to 100%).
103% <= Z4 <= 105%
106% <= Z5
I've set the 80/20 Zones in Garmin Connect but they won't show in the 80/20 data field
The 80/20 data field does not use the data from Garmin Connect. Only thing we use is the lactate threshold heart rate you can enter as 100% value in your user profile. Please see 8020Endurance:Installation:AppSettings#Automatic_LTHR_setup Automatic LTHR setup.