Powertap G3 hub "coasting power" and 20rpm cadence peak

Dovetailing on a recent PowerTap G3 Hub debugging thread, I thought I’d throw my G3 issues out to the ST crowd in search of empathy/insight.

I’m noticing two problems and I’m guessing they are related. The first problem I noticed was, when analyzing my (G3 provided) cadence distribution, is an un-natural peak at 20 rpm, and no cadences between 0-20rpm:

https://s3-us-west-2.amazonaws.com/thepaceline/screen-shot-2017-01-06-at-11-1.png

The second problem I noticed, is that I sometimes observe a power reading while *coasting. *E.g. I’m descending, not pedaling and seeing (on my Garmin 920xt) a power reading anywhere between 10-200W (the cadence will be non-zero during this time too, often at 20rpm…). It’s not completely clear, but I think this “coasting power” is also getting added on top of the power registering when I am actually pedaling (i.e. If I see a coasting power of 100W, when I start pedaling at what I might guess is ~200W, I will observe ~300W being recorded).

A few answers to expected questions:
Firmware is updatedBatteries are newI’m calibrating before every ride and multiple times during the ride. The calibration seems to temporarily solve the problem, but after 10-15min, I see the “coasting power” come back. Checked that the quick-release was set properly (not too tight or loose)Auto-calibration: Enabled

Any thoughts / experiences / fix ideas before I get on the phone with my wheel-builder & PowerTap?

Coasting power?

My G3 rezeros automatically when coasting.

If I were seeing 100 watts when not pedaling, I’d be on the horn with powertap asap!

I’ve seen coasting power on one occasion - tracked it down to an overtight quick release!

I’ve seen coasting power on one occasion - tracked it down to an overtight quick release!

I adjusted the QR this morning before a ride until I convinced myself it wasn’t too tight… Still had the funky 20rpm cadence and power while rolling. uf. Thanks for the suggestion though (I added it to the list of things tried)

How are the bearings? Check for grittiness and or play in the freehub.