There's a pursuit event which involves a partially-sighted rider at the back of a tandem with a sighted person at the front to do the steering. They both do the pedalling. Does anyone know how the sighted 'pilot' is chosen? Are they allocated at random? Is it a friend of the other rider? If the latter, can they persuade Chris Hoy or Bradley Wiggins, or some other champion cyclist to accompany them, or is there a restriction?