Marathon 2011 -alert-alert-alert-

is it naive of me to think that if you suggested that a future marathon could incorporate a cycled section as part of their schedule and therefore be organised.

I think that would be doable. The set up seems to be finished at least half an hour before the first runners come through. If the workers/police are aware and the ride is marshalled/escorted/limited in number I don't see why it would be unsafe. It would be less fun though (where fun=slightly anarchic/dangerous).