Without getting into the details, if you are getting 0 RPM readings sometime during your time trial on the track, then your average cadence data isn't reliable. And Time Trials are where a power meter is the most useful on the track. Speed, power, cadence data from mass start races isn't scrutinized nearly as much as data from TTs.
There are several instances where floating is a viable technique (i.e. kilo or team pursuit).
In short, this sucks.
Maybe a dedicated cadence sensor will work. But, most wireless PMs get their cadence from the power meter unit.
Last edited by carleton; 12-03-14 at 06:17 PM.