Close to 20 years ago a zone 2 ride for me was all about perceived exertion. I had a heart rate monitor and I was told (from memory):
- stay in about this zone for the majority of the ride
- no coasting unless the decent is dangerous (slippery and/or steep)
- if the ascents are steep go as slow as you can in the uphills to stay close to your target HR but don’t sweat it if you go over - do the best you can
- physically and mentally you should feel stressed out over the ride - zone 2 is relaxed riding
During this time I was also doing 2x20 Z4 hill rides which got me stronger. As I got fitter it became easier to stay in zone 2 as my power and leg strength increased.
Sadly (for cycling) I had kids (but happily for life) so now I’m starting again.