MIAMI (Reuters) - A U.S. motorcyclist made the 5,632-mile trek from the northernmost road in Alaska to the southernmost tip of Florida in 100 hours and set a transcontinental record certified by the "Iron Butt Association" of bike enthusiasts. "I'm a little tired ... a little bit bruised," biker Gary Eagan said by phone from Key West, Florida, on Tuesday, a day after finishing the journey on his Ducati Multistrada. He bested the old transcontinental "Iron Butt" record of 114 hours and 49 minutes, set last year by a BMW rider from Maryland. A few hours after starting his solo...