Often posts don't have enough information to make a sensible reply. From your post it appears that you have done little or no planning apart from buying a plane ticket. Hopefully this is not the case.
How long are you going for? Where do want to buy your bike? What sort of roads will you be riding? What distances? How much luggage, I presume you won't be camping. Etc, etc,etc?
Re clothing, I suggest you want stuff that covers you. The sun is strong! I wear a long sleeved gents type shirt and often !ong shorts to cover the top of my legs. A cap and once the sun is high, a brimmed hat is useful. You could wear cycling gear and slap on the sunblock, but I prefer to simply cover up. Also be aware of any modesty issues in what is essentially a Moslem country.
You will also need to think how you are going to carry your luggage. Most use panniers because they are best. Youll also need a rack.
The more I write the more I wonder how much of this you must have already thought of, so I will stop and await any reply.
Finally, sorry to be pedantic, Beardy, but its not the Monsoon, just the wet season. The Monsoon is not a period of heavy rain, but an annual weather system of wet and dry affecting countries in Asia north of the equator.
