Incidentally, I was just forced to help my Dad marshal for one of his bike rides. Setting these things up is practically (hell, IS!) an unpaid second job for him, and I am buggered if I know why he does it. Anyway, rounding up enough people to man the checkpoints and make tea for the riders is an endless chore. They tend to end up being the long suffering families of the committee and any riders to old or too injured to take part in the events.
Anyway, this year they rebranded the marshals as 'Ride Makers', after the success of the London Olympics 'Games Makers' volunteers. I thought it was cute. Maybe you could give a 'Game Maker' shirt to anyone who helps with the running.