One step forward, one step back.
Quick recap: 2 days ago my streak screen total went from about 308km down to 282.4km (without doing any ride, I was just checking the totals) and that is when I started tracking it more closely.
Yesterday my ride of 28.05 was correctly added to the 282.4km to give a new total of 310.5km
Today I did a warm-up of 1km and the C cat TdZ which added another 14km. My total has dropped to 296.4km.
Ignoring the 1km warm-up that’s a total loss of 28.1km (the 14km ride today + the loss of 14.1km in the total).
The ride I did yesterday was 28.05km. On the 25th Dec I did a 28.1km ride (but also a 2km warmup on the same day). On the 15th Dec I did a 28.1km (no warmup).
BUT WAIT, the elevation gain seems to show what’s really happening here. Yesterday my total elevation was 2419m. Today it’s 2289m. A loss of 130m. If we add the elevation gain in the ride today (246m of hilly Yorkshire) we get a total difference of 376m which just so happens to be exactly the same amount of elevation in the 28.05km ride I did yesterday (B cat TdZ).
It seems that what is happening here is the weekly total has added up a certain amount of rides (unknown exactly how many, it could be x amount of rides over the last 3 weeks) but when it gets to that certain amount it has stopped adding and is overwriting the previous ride with the current ride.
For example, the code might be set to only count the last 21 rides over the last 3 weeks. If you’ve done more rides in that time (multiple rides per day) then it might not be adding them all up plus you’ve hit the 21 counter limit and any new ride is overwriting the last one. But that’s just speculating on how the code might be written.
If your last ride is further than the previous ride the total goes up by the difference, If your last ride is less than the previous ride your total goes down by the difference. I rode 14km today, yesterday I rode 28.1km so my total went down by 14.1km (with a corresponding change in the elevation total).
EDIT: Daily changeover time so I thought I’d check the totals again without actually doing any ride. It’s back own to 282.4km and 2042m climbed which is the previous total minus the Stage 1 TdZ (14km and 246m) I did this morning. It looks like the ride this morning has been wiped out from the totals.
So maybe Zwift has accumulated some totals (282.4km in my case). Then if you do a ride it gets added to those totals then at the end of each day it erases those new rides. The question then is what is that 282.4km the sum of?