Travel by motorbike

Motorcycle taxi
The "xe ôm" (literally 'hugging vehicle') is a common mode of transport for Vietnamese as well as tourists. They are widely available and reasonably cheap - about 10,000 dong for a 10 minute trip, which should get you anywhere within the city center. Walk the city streets, and every couple of minutes a guy will flag your attention and say "You !! Motorbike?" Longer trips to outlying areas can be negotiated. Always agree on the fare before starting your trip. As with most things, a tourist will often be quoted an above-market price initially, and you need to be firm. If quoted anything over 10,000 dong for a short trip, remind the driver that you could take an air-con taxi for 15,000 so forget it. Occasionally drivers will demand more than the negotiated price at the end, so it's best to have exact change handy. Then you can pay the agreed amount and walk away, end of discussion.
Motorcycle
The 110-cc motorbike is the preferred mode of transport for the Vietnamese masses, and the large cities swarm with them. It's common to see whole families of four cruising along on a single motorbike. In most places where tourists go, you can easily rent your own. Desk clerks at small hotels often run a side business renting motorbikes to guests, or have a friend or relative who does. Tour booths can usually do the same. In small towns and beach resorts where traffic is light, it's a delightful way to get around and see the sights, and much cheaper than taxis if you make several stops or travel any distance. Roads are usually decent, though it's advisable not to ride too fast and always keep an eye on the road for the occasional pothole.
Riding in the big cities, especially Ho Chi Minh City, is a very different matter, and not advisable unless you are an experienced rider with a very cool head. Traffic is intense and chaotic, with a long list of unwritten rules that don't resemble traffic laws anywhere else. "Right of way" is a nearly unknown concept. Riding in Ho Chi Minh City is like finding yourself in the middle of a 3-D video game where anything can come at you from any direction, and you only have one life. Expats who brave the traffic at all typically have an apprenticeship of a few weeks or months riding on the back of others' motorbikes to learn the ways of the traffic, before attempting to ride themselves. Extreme caution is advised for short-term visitors.
Riding long distance in the countryside can also be harrowing depending on the route you take. Major roads between cities tend to be narrow despite being major, and full of tour buses hell-bent on speed, passing slow trucks where maybe they shouldn't have tried, and leaving not much room at the edge for motorbikes.
Two main categories of motorbike are available to rent: scooters (automatic transmission); and four-speed motorbikes, the gears of which you shift with your left foot. Rental agents tend to steer foreigners toward scooters if available, on the (plausible) assumption that they don't know how to ride motorbikes that require shifting gears. Motorcycles of 175cc and above are only legal to ride if you make a connection with a Vietnamese motorcycle club.
Most places you would want to stop have parking attendants who will issue you a numbered tag and watch over your bike. Sometimes these parking operations are overseen by the establishment you are visiting, and sometimes they are free-lance operations set up in places where a lot of people go. You will usually see rows of bikes lined up parked. Depending on circumstance, you might park the bike yourself, or just put it in neutral and let the staff position it. In all but rare cases you keep the key. Parking is sometimes free at restaurants and cafes (look for "giu xe mien phi"). Elsewhere, fees range from 2,000 to 5,000 dong.
Traffic police in the cities pull over lots of locals (often for reasons that are hard to discern), but conventional wisdom has it that they rarely bother foreigners due to the language barrier. Obeying the traffic laws is advisable just to be sure. Licenses (to operate motorbikes) are required, although many people have been known to drive without them. Helmets are also required by law as from the December 15th, 2007, if you don't have it already, ask your rental agent to provide them. You should also check that your travel insurance covers you for any accidents that occur, particularly if you do not have a motorcycle license in your own country.

Source: wikitravel