The Northwest Vietnam loop takes us from Hanoi to Mai Chau, followed by Son La, Dien Bien Phu, Sapa, Lao Cai and Yen Bai before bringing us back to Hanoi. It is best to plan five to six days for the trip, so that you can ride at a reasonable pace with adequate time for sightseeing. The minimum number of days required for the trip would be three days. Personally, I spent four days for the trip.
Map of North Vietnam and route taken