Originally Posted by DaveWC

I wasn't saying that mine didn't work properly ONLY in <40ºF. It rarely worked properly then, but in warm weather there was typically a period of 5 minutes here or there where it reported HR about 30-50 beats below actual. I tried many positions but none had any appreciable impact. I know that all HR monitors have problems, my chest strap would often over report HR in the 200s for minutes at a time.