I have a noticed quite a few pro riders using heart rate monitors as I see their chest straps. I thought the day and age of heart rate monitoring was gone , with the advent of power meters and watts per kilo ? Does anyone know why they are still using these units ? I think the pros know when they are in the red ? I think they know when they are going to "pop" and can simply watch their wattage on their head units. So if anyone has any insight , much obliged.