I measured, using one minute, the suggested time period, and it was 23 (very good). I've now had my 965 for about three months and it always shows 11 beats. After every run. Does not make sense. Can anyone explain? I know they use two minutes (not sure why), but if I got 23 after one minutes...? Disappointing. BTW, I always use Garmin's chest strap for the better accuracy.