just to parallel the enduro idea of adding a new twist to mountain biking, after watching the dakar rally a few years, i had an idea to compose a mtb rally. the concept was to use an area that had lots of single track crossed with two tracks and to use both parts of the two tracks with the single track. throw in a couple control points/ check points and send people out in intervals and that would be your race. i had about a 5 mile course for hanson but as soon as i had it completed, they re routed a few trails and screwed up my road book. here's a primer on rally road book for moto's but could be transposed for mtbs pretty easy,
http://cdn.shopify.com/s/files/1/0061/7 ... ion.pdf?16
the tough part would be setting the course and finding a cheap road book reader for a mtb.
