Looking for new thrills and a change of pace from riding the local roads, these avid cyclists took to the wilderness on single-speed bicycles with balloon tires and coaster brakes – usually old Schwinns from the 1930s and ’40s. They’d ride or push these 45-plus-pound beasts – affectionately known as clunkers, ballooners, bombers, fatties or fat-tire flyers – up the hills, then blast down the treacherous slopes at death-defying speeds . . . just for the thrill of it.