There's a section of the Gloucester outer ring road that's single carriageway and is always a bit of a bottleneck. I was driving along it yesterday and it was very slow, about 5 mph or so. The two lanes are separated by a strip of chevrons with dotted sides so it's perfectly legal to go into them and these chevrons go on for a mile.

So there was a bike behind me for the whole of the time we were stuck in traffic. When I was riding I'd have been up the centre like a rat up a drainpipe. I can't figure out why you'd ignore one if a motorbike's best features and dawdle along behind cars.