Motorbiking in Asia forum

Hi everyone, I am wondering if any of you would be able to propose a route from Hanoi to HCMC for me. I am planning to buy a motorbike and ride down South although I am unsure of where the best places to stop along the way are, how far it is realistic for me to travel each day and how easy it will be to find accommodation at each destination. I would like to travel along the coast if possible and am not fussed on great nightlife, more taking in the scenery, I want to relax! I have 26 days although my flight departs from Hanoi so I will need to leave time to get a flight or the train back to Hanoi. I would also like to visit HaLong bay or to avoid the tourist scene there, travel further round to Bai Tu Long. Is it imperative that I chain the bike up when I am not with it and if so can I buy a decent lock and chain in Hanoi? Thanks guys and gals!