Any motorbike trip is inherently dangerous, the risks are always enormous. One accident can cost you your ability to walk or your life, that is any ride on a motorbike… That being said, thousands of tourists buy motorbikes here and the overall majority go home safe. A lot of inexperienced riders will leave with a scar or two from silly falls.
If you have motorbike experience but had never ridden “Asia” style, you should buy a motorbike in Hanoi and had to learn in a very intense environment very quickly but put down several hundred kilometers.
You can read 8 tips to survive in traveling Vietnam for Backpackers for more information.