Most backpackers driving Vietnam will drive in flip-flops, shorts and a T-shirt.
We highly recommend buying a new helmet and at a minimum wearing shoes and not flip-flops! Feet are the first body-part to hit the ground in a scary incident and having shoes to balance a bad situation is a very good idea!
Shorts and a T-shirt are up to the travelers discretion and we are unable to advise on this. Speeds are slow on the lower powered models and we understand the attraction of backpacking light in a hot country!
On the 150cc motorbikes we highly recommend full clothing as the average cruising speed falls in line with speeds that can cause some serious damage.
The North and South have different seasons – travelers are likely to experience the sun, the rain and the cold. It is worth bringing clothes for all conditions.
Customers who motorbike at home do sometimes bring leather jackets and full motorbiking gear. Upon arriving few customers opt to actually use their gear having experienced the general road speeds.
Most models of motorbike can carry up to 20kg of luggage. The less luggage and the better the motorbike will drive. Bags can be sent on the train between HCM and Hanoi for $15.
Laundry shops are everywhere in Vietnam and there is no need to travel with a mountain of luggage and spare clothing.
Slim down as much as possible for driving performance and convenience. Try to fit excess into one bag to send by train.