Well, I do it by a vaguely defined "day" because traveling is fluid. You generally aren't going to be moving constantly for exactly 8 hours every single day, and so both the km/h and km/day are just averages that I provided to give a feel for the travel speeds. Perhaps my thought that people would likely walk for more hours in a day on average than they would bike is faulty, but I will admit I didn't put hours of thought into those numbers. 

They aren't supposed to be precise (that said, I've edited my numbers to match yours; might as well give them easily divisible hour amounts). The intention is that each player/character can determine whether they would be hasty travelers, moving faster than this average, or exploratory travelers who stop and get sidetracked all day, moving slower than the average.

The travel difficulty levels for each route/area are also obviously up for debate. I think the more difficult ones are obvious, but the difference between Level 2 and Level 3 might be tricky to determine.