We know what you're thinking. Mountain biking? In Houston? Well, our famously flat town has its own version: bicycling the bayou. The best-kept mountain-biking secret in town is the Ant Hills, a system of ten-plus miles of trails and paths along Buffalo Bayou from Wilcrest to Highway 6. The prime off-road action follows the gully's southern side from Kirkwood to Eldridge, where it meets up with Terry Hershey Park. The mostly single-track trails of packed dirt and slippery silt twist and turn along the water's edge among thick vines and skinny pines, oaks and catalpas. The trails are intermediate to difficult, but they often split around obstacles, which allows a cyclist to tailor the ride to fit his abilities. A rider also can come up for air at several points to join the walkers, in-line skaters and joggers on the more peaceful system of asphalt pathways above the ravine. No, you won't see any mountains on this ride, but if you're not careful, you could come face-to-face with a more common Bayou City sight: poison ivy.