Hi Paolo,
Just downloaded the latest BLEVo (3.8.7 for Android) and discovered a problem in the FIT file produced for each ride. When you stop pedalling and cadence is zero, the FIT file contains no cadence data for those datapoints. The values should be 0 but instead they are blank. When you start pedalling again, the cadence values are present and correct.
I converted the FIT file to CSV and you can see the blank values for cadence when they should be zero. When I import the FIT file into RideWithGPS you can also see the blanks in the cadence graph.
All other data i.e. speed, heart rate, rider and motor power, battery % etc. appears correct.
I've been waiting for you to include FIT files for a long time, and this is a great addition.