Remote Asia does have partners and friends in Vietnam for motorcycle trips. We recommend Explore Indochina, run by Digby (Aussie) and his knowledge Vietnam is unmatched. He's expanded his trips to include tours with restored Ural side cars. For rentals, Mr. Cuong is the best source in Hanoi. He can be contacted at cuongminsk@yahoo.com.
Cong
Ty Khao Sat Duong Mon Chau A 
Explore Indochina
Suite 500, Khach San Tuoi Tre, 2 Tran Thanh Tong street, Hanoi, Vietnam
Tel 913.093.159 or (+84) 918.763.515
Fax: (+844) 972.1607
International Vietnamese Tourism License : 0703 2007 TCDL-GPLHQT