I'm a motorcyclist, and doing what you describe is illegal and stupid. There are two kinds of motorcyclists; smart ones and dead ones. The vulnerability of motorcycling very quickly trains you not to do what you've just described. The smart ones, the ones who survive, have to be smart, because there's no safety net of crumple zones and airbags to allow you to be stupid. People who are vulnerable like that are usually the safest, because they have to be on their toes. People who think they are safe are usually not (and that does apply to motorcyclists too, the dead ones; plenty of them are deluded about how safe they are, and do things like you've described).

If you've encountered motorcyclists riding between lanes on a moving motorway, just be aware it won't be me; I'm not dead yet.

The man with the gun, or the man in the 4mpg Land Rover; both are men running blindfolded through a volcano because the salesman convinced them their paper suit is fireproof.

Lane-splitting as the Americans call it, or filtering as we call it, is only legal in Britain when the traffic is stationary (stuck in a queue on the M25 for instance, or waiting at traffic lights).
(Musuko, Tue 10 Feb 2009, 17:02, Reply)