I use a Garmin Edge 705. The strap will read a low heart rate if the strap gets too loose or if the strap gets caught up in my bra band. What I do before every bike ride is after turning on the Garmin, I make sure the heart rate is showing on the display and that it shows a normal standing around fussing with the bike heart rate range, like in the 80s or 90s. If the heart rate reads lower, for example 35, then there I am out in the public, unzipping top layers and adjusting my bra and tightening up the chest strap. When the heart rate reads normal, then I put the Garmin on the bike and I am ready to go.

Most of my cycling friends use a Garmin and they are always posting links to their rides on Facebook. Over time I've seen enough Garmin data from different cyclists to know that for cyclists in my age range, male and female, our average heart rate on a ride is 120-140, depending on the elevation gain; I am age 57. Younger cyclists and/or cyclists who are not very fit may have a higher average heart rate.

I reviewed my ride history at Garmin Connect and for a ride that is 70-80 miles, my calories burned is between 2500 and 3000 and my average heart rate is around 130.