The people riding bikes you are observing in the middle of the road are obeying the rules and trying to stay alive by preventing close overtakes. Roads were designed for people, horses and bikes - why have we let cars take over?
I am not in favor of lane blocking, blocking an entire lane leading to pile up of vehicles 100x heavier than them so a biker can go on a joy ride in the middle of the road which is actually illegal in most countries, including Singapore.
