I think the important thing with such an arbitrary metric is that you figure out what each level of rpe means to you, build your system and try and be as consistent as possible. Might be worth taking notes on rides regarding their intensity so you can refer back to them too.
Could someone advise on setting your rate of perceived exertion for a ride?
Do you set it as an average across the ride or set it in response to the peak exertion during a ride?
I think I am under-representing my RPE.