The power numbers I produce on the turbo and on the road are almost identical and my heart rate matches up with these power zones on the road for zones 3+. I currently have an FTP of ~295W (4.21w/kg) making my zone 2 power 162-220W and when I ride on the turbo these numbers correspond really well to my zone 2 heart rate of 115-141bpm. But when I ride on the road I have to keep my power way down at around 55-60% of FTP to maintain a zone 2 heart rate, otherwise it easily moves into zone 3. For example, if I ride at 175W on the turbo my heart rate is steady at 125bpm, but on the road I would struggle to keep it below 141bpm and it would drift up to 145bpm-ish, despite it feeling super easy.
I don’t really understand why this is and it means my zone 2 rides outside are about 50-60W down on my turbo rides and often means on long rides I average zone 1 power.
Anyone got any thoughts? or training tips? Should I just ride in zone 2 power and ignore HR and look for an improvement over time?