Well I'm a cyclist and have cycled in HCMC. That is not an easy city nor Vietnam in general for cycling as the traffic is hectic to say the least. But if you learn the more quiet routes its ok I think. Now, I do want to encourage you to try cycling. Everything is strange the first time even if you've done it before... Imagine driving a car if you've not driven for years... Perhaps rent a bicycle for the day and take it slowly. I always think if others can do it then I can too.. You can. In a hot climate it really is a great way to get around. If you do buy one make sure to buy a proper lock as well. Second hand bicycles are quite good too if you just want a simple one...