Are you racing a gravity event at nationals?  Then read this: (team officials, forward it to your nat's squad)

DH: The bigger the bike, the better.  For all the XC racers going for the omnium, it's time to borrow a friend's DH sled.  Due to the fact that it is incredibly rocky and loose, you'll want large tires (2.7ish) to float through the loose stuff and possibly DH tubes to protect against flats.

4X: The course is narrow, and passing will be tough.  To be truly competitive on this course bring a 4"+ bike if you can - a hardtail won't cut it.  It's loose and very rough.

DH helmet cam: http://www.youtube.com/watch?v=DRg0o1MrMmk 

4X helmet cam: http://www.youtube.com/watch?v=1FkF1KsXrr4 

I'll be the designated fun have-er at nats.  If ya'll need a helping hand, let me know.

- b

PS - Bring lots of tubes.  The local shops have a habit of selling out quick on race weekends.