I will try some of the suggestions made here like checking my pulse to see if it matches up with the Garmin before we start. I still think that something is screwy with it. I've been working out nearly all of my life, so yeah, I'm in decent shape cardio-wise...but I still don't get that my burn is so low on bike rides. I understand that I do have to work a bit harder at it to keep my HR up, but an average HR of 108 over the course of a 4 hour ride??? Just doesn't make sense. I'm pretty sure that it's NOT me, and definitely something wrong with the Garmin unit or HRM itself. I'll have to look into this a bit deeper to see if I can come up with anything.

Thanks everyone!

Linda