Best road to use in Vietnam
 

Does anybody have any thoughts on the best main road to travel on through Vietnam from Saigon to Hanoi, some people think hwy 1 but I am told that this is very busy and others say hwy 14 the one that is inland slightly, it is said to be more scenic if the ocean is not your thing but considerably less busy. Any thoughts would be welcome, I am actually on a bicycle so traffic density is a major consideration but hills are not a problem.
Mark