* Lennard Zinn is the top-selling bike maintenance author by huge margins with over 200,000 units sold in all editions.* The Zinn & the Art of Series is the best-selling bike maintenance reference in cycling. * Mountain bikes are the most popular bike style in the U.S. 1 in 6 Americans rode a bike last year. * 15 million core cyclists rode their bikes on at least 52 days last year.