I have been on the cross country skiis the last 2 nights. It was 5k each night at a good pace for a person of my ability. I pushed hard and it got me to thinking how hard it would be to do the Birkie. The Old Bag is doing it this year and we will be cheering her on. Anyone doing the Birkie has to be in very good shape. 54K to ski it...50K to skate and both of the Kortelopet's are 23K each. My friend CAD could do these with ease, but I know for a fact that I would have to struggle through, but I would make it even with my limited ability.