Well I had a new Nordic skiing experience this past weekend. I skied the 2012 55km Canadian Birkie, as a sweeper, which I was not physically prepared for. Our speed is only as fast as the slowest skier. There is however, cutoff times at each feed station. If the skier does not reach a station in a particular time, they must quit the race.

Volunteers were at each feed station or at intersections, directing skiers to the 31km or 55km course. It was for some, an all day affair but also enjoyable. When the sweeper reaches a station, the volunteers can then call it a day, pack up, and go home.
Eight hours on skis at slow speeds is really hard on a person.

The weather was -18C, sunny, with a 15km wind at 930am start time, which was certainly cold for those that were not prepared. The tracks stood up well especially considering how little snow there was. The air temperature warmed to about -6C at the finish line.