What I found over marathon season and my 80+ mile race in January is I would have trained long rides on my mountain bike, even if it was long road rides. Most of my long rides for endurance were road rides, I would do some longer mountain bike rides but usually only 20 +/- miles. I found the mountain bike position is different on my sit bones and back, I was really sore there after a race. So this year I will probably put slicks on my mountain bike and ride it on the road to train. Can't wait to hear about your race, I have a 100 miler on my list of "must-do" but it is a few years off.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan