hanoi city is large city with over 8mil people but 90 % local people use motorbike and car for travel, bicycle like a kind of exerse but if you do bicycle tour to visit hanoi city it be great idea, you can see hanoi by slow motion and can see close to you, and you can get intouch to the local people, cycling on the trail, the valley and alley road, you will see local people live in side, it will be one of the best way to see the city, and ands bicycle will ride on the trail road in the poor part of hanoi city, it be interesitng way to see the poor part of hanoi, you will know more local culture, bicycle will be come nice way for you to visit hanoi city