Normally when a biker comes up behind me in the fast lane on the motorway i move over to the right a little and they dive up the inside, seems alot of other people do it too, kinda like an unwritten rule.

What gets on my goat is those people who dive up the middle lane to get past the line of cars in front, then cut back into the fast lane when they meet a slower car, only gaining about 2 places (and cutting their journey time by about 2 seconds ) but having to drive like a maniac to do it