The best way to see Vietnam is by bike, and there’s plenty to see. There’s enough infrastructure to make this trip doable, the weather’s warm year-round, and a bike is the chosen form of transport for the locals, especially in the larger cities.
Honda’s world-famous C90 Cub may be all the bike you need—a 250 twin is about the biggest thing you’ll ever want. If you’re intent on bringing your own bike, a 250-class dual-sport will be about right; most riders rent or buy a bike in-country. Know ahead of time that the bureaucracy of travel permits and bike importation will require some patience.
Vietnamese traffic may seem crazy, but it isn't, really—once you learn to embrace the chaos and go with the flow.
Be prepared to deal with unimproved roads—another reason why an indigenous bike will be the best choice: the locals know what works here. November to February are the coolest and driest months—the monsoon season in all of Indochina is legendary.