friedel, I have just read your two links.
1) Taxis - I have carried many bikes in normal taxis - both boxed and unboxed. Regular taxis include Toyota Corolla, ThaiRung Adventure , Suzuki APV and Toyota Innova. Limo taxis can include Toyota Camry, Mercedes Benz and BMW so how much bigger is the Camry compared to the Corolla? Would the limo driver let you put a bike in his car?
2) Public transport is 'time consuming and expensive'? I will agree with you on the time consuming (at times) but not on the expensive!
3) Bangkok is huge - it is! You have just mentioned two tourist areas.
4) Just where are the bike lanes? I have seen two painted lines on the pavement but that does not make a bike lane! Look at this example:-
Would you call that a bike lane? I wouldn't!
5) Pollution - if you are riding in gridlocked traffic in central Bangkok, of course there will be heavy pollution! Get away from the centre.
hackbike6 - I believe the best place for rentals is
http://spiceroads.com/about/bikes/
I live in the Lat Phrao area and rarely venture into the city although it is only a few miles away. There are a few of my videos on
http://www.youtube.com/profile_videos?user=hipponokloo
One thing to be very careful about is 'Priority from the left'; in the UK, we are used to vehicles on the main road having priority but it is not so here - it took me a long time to get used to it! You often see traffic on the main road stopped to let the side traffic out.
I don't know what size of bike you use but if you would like to join me on one of my circuits one morning - just let me know how far you would like to go, if my Trek 3900 21" would be suitable.