I rode 30 minutes on the Cybex bike using the heart rate program at 138bpm. I rode a total of 8.46 miles. It's still challenging to maintain a cadence of 90rpm. It's also challening making it through the 30 minutes.

I don't know if the battery on the HR transmitter is dying; I couldn't get the one bike to detect the signal at all and the other one had intermittent times when it lost the signal.