I just check Garmin Connect and it usually only takes me less than 10 minutes before my HR goes back to normal. After a ride, my 2 minutes heart rate recovery is about 30-35 BPM (I keep my chest strap until then to make sure the data is legit). My resting HR is in the low 50s and my workday HR is about 75 BPM. My riding HR is averaging at 145-155 BPM. I'm 55 years old. When I start riding back in the Spring, it would take me over an hour before it goes below 100 BPM but as the rides pill up, my recovery HR goes down.