I don't have a power meter or measure HR on the bike. No doubt that type of training has it's benefits. I'm just too lazy to have to think about data and try to enjoy the ride. And, I don't want to invest the money in something that doesn't matter very much to me. I clearly see the benefits and the enthusiasm people have for it but at age 75 I just don't want to be "in training" when I'm on the bike. We do have a spin bike/trainer something like a Peloton that measures HR and RPMs and gives readouts about zones. When I do the various programs I am almost exactly where the trainer and program say I should be.