PowerPod Suddenly Reads Low Power, Negative Rolling Watts

[the shovel]

I've been fine tuning my settings using the Youtube video on how to use the check calibration and settings.

Everything seemed about right after my last adjustment - CdA of .420 for my cross bike, Crr of 0.0045 for my Schwalbe Pro One tubeless tires, and my speed/effort is close to the same for out and back rides.

But on today's ride, I noticed that power reading showing on my Garmin 1000 Edge stays at zero for much of the time. Looking at my files after the ride, I see that the latest ride file shows a Crr of -0.0305 and rolling numbers for the ride are negative. This is not what is set in my active profile.

I've attached the files for the two latest rides. The earlier one seems about right, the later one is today's screwy ride.

Any suggestions on what to do about this?

Thanks,

Rick

iBike_08_03_2017_1014_33_km.ibr

(462.52 KiB) Downloaded 243 times

iBike_08_01_2017_0933_30_km.ibr

(381.77 KiB) Downloaded 249 times

[Velocomp]

What's happened is that your PP is so far out of calibration is that is in never-never land.

Use Isaac Device/Setup Device to initiate a "Best Accuracy" calibration.

Once you do this I think all will be well.

[the shovel]

That worked great - thank you for the suggestion. The calibration ride went as described on your Youtube video - easy to follow.

One minor question remaining. The calibration ride set the CdA at 0.379 M**2. This is on a cross bike which has the top of the handlebar at the same elevation as the top of the saddle. I read on another post that 0.420 is more typical for a cross bike. Should I leave it as calibrated or change the CdA to 0.420?

[Velocomp]

0.42 is for a person who is about 6' tall.

If you're shorter than that then I would set it to 0.40