The Outdoor Industry Association and its non-profit arm, the Outdoor Foundation, provides excellent research on mountain biking and 113 other outdoor activities.
The Outdoor Foundation recently released its latest report on outdoor recreation. Biking—including mountain, road and BMX—was cited as the third most popular activity among all Americans ages 6 and over, behind running/jogging and fishing. Biking was also the most popular activity among youth ages 6-17 and in the top five among the 18-24 young adult age group. The report highlights that biking is a top "gateway activity" for youth and that participation in BMX biking grew 31 percent in 2010. A new section of the report described significantly higher participation rates in outdoor activities for those with biking routes and trails near their homes.
Many of the free reports can be downloaded as PDF attachments, so a fast connection to the Internet will help you save time.
The Outdoor Industry Association is a corporate member of IMBA.