Cycling in SE Asia (Bangkok)

Hello,

I'm currently planning a cycling trip and was wondering if anyone here has done some cycling in SE Asia before. I'm also in need of a bike and have heard that cyclists sometimes sell their bikes when they've finished touring around the country. Does anyone know where I could locate more information on this topic? Or if there are forums where cyclists typically post gear for sale?

If anyone has done any cycling around here I would also love to meet up to hear about their experience!