Running a marathon doesn't prepare your body to ride 50 miles. I can't tell you how many runners decide to start riding and think they can just go out and ride 50 miles and are sorely surprised. Sitting on the trainer for an hour also doesn't prepare you to ride 50 miles. I know, it's none of my business, but Sarah's an example to other riders (her TnT folks) and this is something she'd probably never let one of her athletes do.

Girl!!!