Heart Rate vs RPE decoupling

I don’t ride with power outdoors. Hence cannot use the heart / power decoupling as a sign to bring a LSD ride to a close.

I do ride with heart rate outdoors. Something I noticed after I’d had a cold in October was that my early rides (after the cold passed) my RPE was divorced from my HR. What I mean by this is that I have a pretty good sense of my RPE and how that relates to my HR. They are anchored pretty well together. But after my cold my RPE was significantly higher than my HR and it’s rate if increase would indicate.

I’m therefore wondering if RPE vs. Heart rate can be a good measure for working out when to bring a LSD ride to a close. You’d calibrate the RPE vs.HR response in first hour. Then just keep an eye on it and when RPE seems much higher vs. HR compared to first hour. It’s time to bring it to a close.

My other thought is leg fatigue but since I ride brevets the legs can often just keep going and going.

@Phil, I think that’s completely acceptable. What you might also notice is that your cadence can be a good indicator. When I see on a long ride that the legs are having difficulty spinning at the same cadence, that’s usually a sign that things are changing and you’re probably getting near the end of that ride. Also paying attention to that cadence and the gearing you’re in - what you’ll notice is that cadence goes down and you select an easier gear to maintain cadence = lower speed. I would pair your RPE/HR with cadence and I think you’ll have some god indicators of when to end the ride.