Originally Posted by chadwick

One thing to watch for us the Garmin HR straps tend to flake out easily and report erroneous data to the device. I've had two do this from some internal wiring problem. They also are rather prone to 2.4 GHz interference which I've run into at times.

Your data doesn't look like that was happening, though. If you ever see stair-step like pattern in your data, it's probably interference or the strap going crazy. But sometimes I've had mine report a pretty solid 30 BPM higher than reality for the entire duration of the ride. Usually when that starts happening it's a sign that HR strap is near death. But since yours is new...