If you are craving a challenging ski workout that will train your agility, boost your strength, and add variety to your skiing, you should look no further than your local fat-bike, singletrack ride. Have you ever tried to keep up with the fat bikes? On their trail? “Hardest workout out there!” said Eli Brown, a longtime U.S. Ski Team volunteer wax tech from Michigan, who is doing the majority of his skiing this season on singletrack....