AeroPod, PowerPod and Newton

I recently set the powerpod up on my second bike. After a recent ride I used the Isaac software to check the calibration. It appeared to work but when I attempted to send the update to the powerpod it gave me an error. It appears the friction coefficient was a negative number. I've posted both the workout file and a screenshot after doing the calibration check. Can you give some insight as to what is going on.

Also, I do change the powerpod periodically between bikes. After doing the initial calibration ride and then checking the calibration on subsequent rides is there a need to check the calibration overtime I switch it between bikes. I understand there will be the 8 min initial period, but after that should the power numbers be accurate?

It looks like the original calibration of your PP has changed. This is why you get a negative friction value.

I would make sure your PP is attached so that it cannot rotate, and so that it hits the stop on the mount, then I would do a new calibration ride.