So, I recently got into road cycling and have been riding for a few weeks. My average speed for most of my rides is around 25 km/h for the first 40 km and drops to 15 or 20 km/h for the next 20 or 30 km. I want to know if the speed that I'm riding at is considered as "slow" or "walking pace" or is the speed that I'm going at pretty good. I'm not sure what speed I should be aiming at.
Note:
I am preparing for long distance rides, mostly flats more than 80 km. So I want to know what speed I should be aiming for, not to win, but the speed that one should ideally be at.