Abstract: The present invention provides a portable and expandable track or velodrome 10 for racing bicycles indoors and outdoors. The portable velodrome 10 includes a support structure network 18 that circumscribes an infield area 12 and a plurality of modular track surface sections 30 removably mounted on the support structure network 18 to form a banked track 22 having a racing surface. The modular track sections 30 are mounted on the support structure network 18 with track section mounting elements that do not interrupt the racing surface. The portable velodrome 10 further includes a substantially horizontal track section 28 extending from a bottom of the banked track 22 toward the infield area 12, and a transition surface between the banked track 22 and the horizontal track 28.