Always wanted to ask, but though it was a dumb question due to drift etc.
Should the zones step up for power meters always broadly match that of the same zones for heart rate.
And if they do, how do you use the information when analyzing a ride ?
There are no dumb questions.
Power and heart rate zones are both similar in percentage to threshold. However we typically divide power into 7 training zones and heart rate into 6.
Zone 1: < 55%
Zone 2: 55 - 75%
Zone 3: 75 - 90%
Sweet Spot: 83 - 97%
Zone 4: 90 - 105%
Zone 5: 105% - 130%
Zone 6: 130% +
Zone 1: < 68%
Zone 2: 68 - 83%
Zone 3: 83 - 94%
Sweet Spot: 90 - 100%
Zone 4: 94 - 105%
Zone 5 105% +
So these are the zones based on your Functional Threshold Power and Threshold heart rate. While riding your zones should match up and if they do not we should do another test to adjust your threshold values.
There are many ways to use this information to analyze a ride. Sadly some riders don’t even use heart rate, but you can get a lot of information by seeing heart rate along with power. You ideally want to see your heart rate stay consistent during a zone 2 ride. You don’t want to see it drift up more than 4 - 5% if possible. You can really see at what point in a steady endurance ride this happens. Then when doing intervals you really want to see your heart rate being similar from the second set to the other sets. Reason I say the second set is that the first effort is mostly a warm up effort and your heart rate takes time to react to the effort. This is one reason power is so beneficial. It is instant and heart rate takes time to react.
Also heart rate has a few more variables. Such as fatigue, caffeine, heat and etc. So these things can cause the heart rate to be higher or lower. So when training it is important to use the three metrics as one. Power, heart rate and perceived exertion. You really want 2 out of the 3 to be right / feel right.