Gear-grinding slickrock climbs. Amazing Pacific vistas. Brake-flicking descents. The Sierra Madre is made for mountain bikes. If you want to ride in Copper Canyon, that vast series of gorges eight hours south of El Paso, Texas, you'll need strong quads and a guideNew Mexicobased Remolino Adventure Works offers eight-day trips ($1,400; remolino.com). Don't have that kind of time? Explore the foothills south of Puerto Vallarta with Eco Ride Mex ($140; ecoridemex.com). Opt for the Yelapa tour, which starts in El Tuito, 28 miles from Puerto Vallarta, and zips for 34 miles along ridgelines overlooking rainforests and blue Banderas Bay. A steep drop into Yelapa leads to a taxi-boat lift back to Puerto Vallarta, where the waterfront Buenaventura Hotel awaits (doubles, $150; hotelbuenaventura.com.mx).