Powertap G3 cadence peak at 20rpm

[eisforurgent]

Looking at my cadence distribution, as recorded through a newish (<500 miles) powertap g3, and I'm seeing a strange peak at 20 rpm (it has appeared on all the rides so far):

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

My first guess was that this was reflective of the G3's data sampling rate, and it may be, however I can't seem to find any documentation about what the actual sampling rate actually is to confirm/refute this.

Has anyone seen this sort of thing before or know whats going on?

[R3awak3n]

could it be because the g3 is not that great at measuring cadence, at least before cadence is high enough