Phil's right.
I am engaged in debate with a number of my biking mtb friends. They are claiming that a 30-40km mtb race is as tough as racing for150 miles. I suggested that the reason why, after leaving mtb racing and coming to road, it took evans and hesjedal a while to get up to speed was due to the difficulyt of learning how to race for six hours at a pop. Not for an hour.
They cant handle the truth.