Cyclocross -- As part of its "Step Up to Health" campaign, Howard County Department of Recreation and Parks will join forces with the Baltimore-based Lateral Stress Velo's cycling club and team to sponsor an inaugural "Rockburn Cross." The event, which is to begin at 10 a.m. Sunday at Rockburn Branch Park in Elkridge, is a hybrid between high-speed bicycle racing and technical mountain-bike racing, and includes man-made hurdles and natural obstacles that require riders to sometimes dismount and run with their bikes. The races feature novice to professional categories. Registration closes at noon Friday. A US Cycling license is required; it can be purchased on the day of the event. To register: Steve Heinbach, 410-313-1691 or visit www.rockburncross. com. Admission is free to spectators.