San Felasco Hammock Preserve is one of the most extensive trail systems in the state and is only a fifteen minute drive north on 441 away from town. Fast trails with plenty of technical sections and elevation change (for Florida anyways) in a beautiful setting among many of Florida's endemic wildlife, including turkeys, deer, tortoises, snakes, and bobcats.
From San Felasco site:
Now at 7,000 acres (with the newly acquired Fox Pond site), the San Felasco Hammock Preserve State Park is one of the finest examples of the climax mesic hammocks remaining in Florida. The park is located to the northwest of Gainesville, in north Florida's Alachua County. The limestone outcrops and extreme changes in elevation provide conditions for at least 18 biological communities within the hammock, including areas of sandhill, hydric hammock, upland pine, and swamp. Thanks to the region's karst topography, sinkholes, steephead springs, ponds, and small lakes dot the landscape. Blues Creek, Turkey Creek, and Cellon Creek all enter San Felasco from outside the park boundary and flow through the park, finally dropping into swallows, which drain back into the aquifer. The Friends of San Felasco Citizen Support Organization (CSO) created this Web site to provide you with information about the many activities available within the San Felasco park. If you enjoy using the trails in this amazing preserve, we encourage you to become involved with the CSO to help maintain existing facilities and to help plan for its future. To learn more about the CSO, see CSO.
San Felasco trails are a Multi-use trail system open from dawn to dusk everyday. If you do not already have a Florida State Park pass it costs $2 per vehicle. Again, from San Felasco site:
The more than 30 miles of mountain bike trails are a network of cross-country single-track that threads through the numerous ecologic zones of this park. The trails, which can be ridden in either direction, take advantage of elevation changes to provide delightful rides of varying lengths that are within the abilities of the majority of mountain bikers. Olympic and world class riders have been known to enjoy their rides here. Maps are in the mailbox at the trailhead kiosk. Directions to the mountain bike trailhead: Take I-75 to U.S. 441 (Milepost Exit 399 - Old Exit 78) and drive south 2.8 miles (through the city of Alachua). Turn right onto Progress Blvd. Drive 0.7 miles to the park entrance. (Continue past the end of the pavement and onto the grade road.)
The San Felasco Preserve State Park website can be viewed here.