Riders in RAGBRAI don’t need a visa to ride their bikes across Iowa this coming week, but they may want to get a passport. It’s a special promotion of the biking event and the U-S Postal service, which created it in 1997.A small stamp-collecting booklet was dubbed the Des Moines Register passport. It includes a page for each community along the route. Regional Postal Service spokesman Rich Watkins says registered riders can get the book, then buy a first-class stamp at the post office in each town where they stop. In fact, Watkins says it may be the kind of keepsake that’s like your old comics or baseball cards.He’s heard someone saw one from 1997 on e-bay advertised for hundreds of dollars.