That would work as well. I am trying to make the process as “automatic” as possible so I am not fiddling around with my iPhone while on the trainer. Alex sent me a link to a workout with an extended warmup that will achieve this automatic transition I think, then just enter HR mode.
Thanks for your idea though!
naturally. an automated HR Based Structured workout seems to fit the bill.
Here is today’s one
https://app.trainerday.com/activities/653eeb3b1ed39339989735b4
At 11 minutes in i switched from ERG to HR control. The target power was the same momentarily, but then it adjusted down as the default value for HR control is less than what i was at. So I moved the target up, and as you can see it took awhile for the power level to be increased.
I assume this delay is because it is still waiting for a HR value consistently less than (Target - 5 bpm) - is that still the case? Personally I prefer it to be more responsive to a HR below the target.
Also, is there a way to have the initial HR target set to a value other than the default value when you switch from ERG to HR control?
That’s my approach as well. Although not for Zone2 training. For zone2, my target is 120. I leave 120 in. And in about 5-6 minutes I’m at that target. Which works for me. I need to get to 140-150W at this moment, don’t need a long warmup for that. It’s different when I want to do a Zone4 HR workout. For which btw the HR mode is amazing. Then I first let it go to 120, for about 15 minutes in total and then I adjust the HR up to 146.
I’m on version 1.4.8 of the app now. Can the app already switch back from a structured ERG workout to HR mode? I believe this was in the pipeline…
I think you should use ERG to bring up to your full target HR. Your HR comes up slowly so you likely need a longer ERG warmup. Does that make sense? Yes we should make HR mode remember your last target so that you don’t have to quickly increase it each time. We will do this ASAP.
Yes you can switch back and forth from ERG/HR now but just not automatically yet.
Automatically means a “structured HR workout”, correct ? I’ll try the switching back this evening, looking forward to that 
Yes, see the other post I just commented on. It will work but not be perfect HR switch because of slow power changes, but there will be a good work around for Z4 HR intervals for example. Let me know if you want me to explain now or just wait.
Let me try it out and I’ll see what happens
5-6 min is a bit short for a warm-up, even for zone 2. Ease in to it, 10-12 min to reach top of MAF zone and there’s a good chance that you will feel stronger.
I was thinking on usability for Z4 intervals, so it’s good that you have a positive experience. But there too, I would probably ride somewhat longer in low Z2, until I start to break a little sweat.
Example of a Z4 workout
Trainer Day - Activity Detail
I believe the warmup time is very individual. For me 5 min is more than enough to get in Z2. When I ride outside, I’m in Z2 right away. I actually need to pace it to stay in Z2, because it’s very hilly where I live. Indoor I usually have an hour, so 5 min warmup, 5 min cooldown and 50 min Z2
If you buy into the whole “Zone 2” concept then the main goal is fat burning. If you move quickly into zone 2 your body says, oh no I need fast energy let’s switch to carb burning. So it’s a much bigger risk that you lose most of the benefit of zone 2. This comes directly from Maffetone. You don’t have to believe it but he really seems to be the expert here. So I agree completely with @MedTechCD that slowly coming to target HR over 12-15 minutes is optimal, i.e. “far safer” to achieving maximum “Z2” benefits to any very slight losses by being below or maximum HR. Again this is all from Maffetone.
Additionally, if you eat carbs within a few hours before your z2 ride your body will also be using them for fuel. So if you are not fasted or at least carb fasted, then the warmup likely does not matter. Following this protocol after a year or so I could run Z2 for 3 hours without any fueling.
I would love to hear your thoughts around Z4 HR workouts, this is interesting. I have not researched this or do I know much about it. As I consider improving HR intervals I need a better understanding of this.
I guess it’s likely to be more sustainable than Z4 power, especially since I see the power is more sweet spot in your example here.
What I’m after is the famous "mitochondial effects’. In normal language, the baseline physical effects. I didn’t know a slower warmup leads to carb usage rather than fat. For the moment that’s not my goal, but good to know.
It’s the other way round. Slower warmup decreases the need for your body to immediately start the carb burning.
The primary mitochondial effects are supposed to come from using fat for fuel
My idea is indeed sweet spot. Much debate if that is zone4 or not zone4. According to Garmin, this is zone4. According to others platforms, it’s not. I have picked my HR target where I can sustain it. And I analysed some of my longer Alpine climbs of this summer to see what HR I was at. When you try to mimic that using “power”, it’s very difficult. And it requires constant manual adjustments. One day is not the other. So I target HR 146 and I go. This is actually the workout I also do 5 min standing up efforts in. GCN recently had a video where they explained “zone 4 efforts”, but then using Zwift. Funny to hear the challenges with it
Yes that makes sense, HR based intensities seem easier to dial in sustainable intervals, I like this. Sweet spot is just the honest man’s z4 I will check out this GCN video and do some research thanks.
If you go MAF (or Seiler), it doesn’t matter if it’s high Z3, Z4 or even low Z5. It’s just ‘hard’ 
Be somewhat conservative because Height and Heat can make for a higher HR compared to being at sea level and normal room temperature.