I have been trying to figure this out for weeks. Every time I ride the resistance has lowered and I need to do spin-down to get the watts up to a proper level.
As a kickr owner, i usually do a spindown before each ride. While the kickr is temperature compensated to a degree, you need to warm it up before you do the spindown.
Here is what i typically do
Enable the blte and wifi on my smart phone
Spin fast (warm up for 10 mins at approx 150 watts)
go into spindown mode
while spindown is occuring, i load zwift on my computer, allow my sensors to pair and select some music.
then get my zwift on.
Unless your using the wheel on version of the kickr, the resistance shouldn’t change.
If you are using the snap then you may need to pump up your tire to the standard pressure.