Every month around the full moon, there's a night ride here in Gainesville, FL at San Felasco park. You bring a bike, helmet and a light. People meet at the trailhead near the parking lot at about 7:30.
Here's a little info about the trails at San Felasco:
"The bike trails include a one-mile beginner's trail (the Cotton Tail trail) that gently winds around the perimeter of the north entrance, a four-mile intermediate level trail (Cellon Creek Trail) that traverses both sides of Cellon Creek through rolling terrain and across small log jumps, and an eight-mile advanced trail (the Tung Nut Loop) off the back of the Cellon Creek Trail that involves strenuous hill climbing, steep switchbacks, many log bridges, and breathtaking views of the north rim of the Sanchez Prairie. The Park's newest bike trail, the Hammock Hub, connects from the top of the last third of the Tung Nut Loop, just east of the powerline "overlook" at the top of the hill. The Hub is a two-mile loop with challenging climbs and large log bridges. The Hub connects to two other trail systems: the Sweet Gum Loop is a short (approximately 1.6 mile) moderate level trail off the eastern edge of the Hub, while the Ravine Creek trails link off of the southern edge of the Sweet Gum Loop. The Ravine trails are for more advanced riders. The trails take you far away from the parking lot and feature short, steep drops, strong climbs, and many log crossings. Taken together, you can piece together almost 20 miles of singletrack unmatched for its quality of cross country riding in the state of Florida. Remember that north Florida's high heat and humidity make for difficult riding conditions: bring plenty of fluids on the trail. Due to the remote nature of the Tung Nut Loop, Hammock Hub, Sweet Gum Loop, and the Ravine Creek trails, you should also consider bringing basic bike tools such as a pump, replacement inner-tube, and a multi-tool kit when riding on the advanced trails."