I have had two rides recently where the Garmin has recorded a momentary spike in HR. The first was on a relatively steady ride on the canal, with a low average HR with a sudden spike up to 171, for less than a second. I decided this was just a faulty reading, from static or a loose jersey. The second was at the velodrome. I had decided to return and retake my accreditation session. My licence to use the velodrome had expired due to my time away. This was a much more active ride; the tests are designed to simulate race activities. I am allowed to use the Garmin to record, but it can’t be placed on the bars where I can see it. I set it to alarm at 163 and informed the coach that I may leave the exercises if it alarmed. I was relieved that it did not alarm even in the sprint simulations. However at the end of the session, I reviewed the HR trace, and it seems that my max was 201, although it was too short for the graph to display it. I am now not sure whether this was jersey related or whether I have recorded some momentary flutter.
So, I now have another thing to keep under review. I will probably keep away from the velodrome until I am sure the spikes are not a problem. Yesterday, I tried a road ride, not too arduous, but with a little bit of climbing. I was watching the HR all the way round and saw no problems. A total of 34 miles at 16.1 mph, which pleased me.