The vast majority of people in Southeast Asia are honest and kind. In general, the hotel/hostel owners are decent people. That said, we locked our bikes every night and rarely left them unattended in the both the U.S. and in Asia. When possible I would bring the bikes into the room in Southeast Asia. If not, I would lock them in a secure place. But that's me. I do the same thing now that we are home.

You are not going to have a good time if you are constantly worried every time you go to dinner and leave you bicycle or gear in your room.

We took along two pacsafes and locked our gear when unattended. It worked for us.

http://www.vwvagabonds.com/Bike/BikeSecurity.html