The best and most reliable Minsk rental in Hanoi is Cuong’s Motorbike Adventure. They are conveniently located at 1 Pho luong Ngoc Quyen (about 300m north of Hoan Kiem Lake). For the exact location on the map, check the Old Quarter map in your Lonely Planet Vietnam
Update July 2010: Looks like Cuong’s website is up!
Cuong’s Motorbike Adventure
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