Funny comment about heart rate going to zero. This happened to me just over a week ago. I was comparing the HR readings of a chest strap to the heart rate measured with an optical arm band. Each sensor was linked to different but identical VDO Z2 computers. Just over 1 hour into my ride, both heart rates dropped to and stayed at zero for about 40 seconds before they (both) resumed their normal readings. I had one VDO computer on my wrist, and the other mounted on the stem. The stem mounted computer continued to display both speed and cadence, just the HR went to zero. I don't know what caused this to happen. Both sensors were linked to their respective computers via ANT+, so maybe there was some interference from a nearby house (that only affected the HR signals)? I've never seen this happen before, and it hasn't happened since. Has anybody seen anything like this before?