From late April to early November, mountain bikers take over Ski Plattekill. With 70 trails covering 60-plus mi, a vertical drop of 1,100 feet, and two lifts, the park is considered one of the top mountain-biking venues in North America. Races for all ages and skills levels take place monthly, during which hundreds of aficionados pitch tents in the lower parking lot. An all-day trail-and-lift pass is $25. Instruction and rentals are available. 1 Plattekill Mountain Rd., east of Rte. 30, Roxbury, NY. 607/326–3500 or 800/633–3275. www.plattekill.com.