Buena Vista is a great destination for mountain biking, and the trails just northeast of town stay dry and rideable practically year-round. It's hard to find a destination in Colorado that is more scenic!
From the gravel lot at River Park, cross the pedestrian bridge, and pedal south along the river, passing a steep predominantly hiking trail on the left to a switchback/junction. Climb left, passing an unsigned junction with the Steep Shortcut
on the left. From this point up, the trail becomes a fitness test to the railroad grade. The trail is not long, but it is an ass-kicker. Pucker up, buttercup!