I’m finding it hard to elevate my HR on the turbo at the moment. Going on RPE, then I’m comfortably in Z2 and yet HR was 20-30bpm lower than I’d expect.
I did 2 hours last night and less than 40% was in the correct zone HR wise.
I thought it might be do to with heat but that was with a fan and the window open and I’d expect being overly hot to give high rather than low HR readings.
It could be a psychological thing as I do hate the turbo.
Any thoughts?

It’s a psychological thing as you hate the turbo.

Pedal faster.

Plus there are no little rests on the turbo like you get outside so it generally feels harder.

Since wheel speed = power output, ditch RPE. Turbos always feel harder, but only speed matters. That and go harder for longer and you HR will increase. It just takes a while to get up there! If you fit a rear speedo and calibrate it according to your turbo power curve you can read XX.X mph as XXX Watts.

For mine, the diameter conversion is about 0.6x the circumference. Then you don’t need RPE at all.

The other thing is about cardiac drift – it takes time to warm up until you’ll get into the correct zones. If I go straight out and onto the turbo it seems to take longer to warm up than if I’m riding.

If my HR, when it gets to steady state, is a lot lower than I’d expect it to be for RPE (or more specifically power) then that can be an indicator of tiredness or illness.

Are you basing your RPE on road efforts? It could be lower as you’re riding at a very steady state on the turbo and don’t have all the little accelerations and decelerations you have on the road that can make RPE seem higher… but then you don’t get the little breaks in pedalling either. Point being that RPE on the turbo may well feel different to RPE on the road.

Edit… Either way, what TiRed said, HR and RPE aren’t perticularly good ways to measure effort. If you can’t get a PM then at least go by wheel speed (or something like TrainerRoad virtual power) to compare or pace turbo efforts.

Thanks all. Yes, I’m basing RPE on equivalent road RPE.
I am a little fatigued but I would expect to be seeing as I’ve significantly I teased training hours in the past three weeks. I’ll keep an eye on it after next week as that is a R+R week.