Some revealing sketches showing the different "zones of invisibility" of which a cyclist needs to be aware when they are near a tractor-trailer or other large articulated vehicle. Original source is the Moving Target blog, mostly centered around the messenger scene in London, UK. So the diagrams all deal with traffic on the left-hand of the road. As some of the comments point out it's worth noting that the bike lanes installed "for our safety" put us exactly in the wrong place near one of these things. Summary: stay well away.