Thanks for understanding my concern for Suzie's well being. Can it be a function of something going wrong with the heart? I hope not.

Suzie says she has a doctor's appointment in October.

Zen, Suzie thinks the HRM is working because she tested it by going for a run, and got an average in the 130s, like normal.

I think Suzie is in great shape physically and yes, she has a high fitness level for her age. But I don't think the reason for the abrupt change in her heart rate is due to fitness level, because since it happened she has pushed herself with more miles and more hills and the heart rate remains low. She doesn't think she can go any faster or push herself any harder, so I don't think fitness level is the cause of every single ride having a low heart rate.

Darcy