This is the only Trail designated for bikes. It is mostly double track, well maintained, old service road type trail. Most of it has one lane (of the double track) that is well ridden, and the other lane loose gravel/rocks. Very Scenic with low grade hills that wind in and out along the shores of Lake Allatoona. Picnic tables along the route. There are a few turn-offs that are kinda grown in that take you out on some penninsulas for added mileage and scenary. This is a great little trail to take beginners, spouses, and kids out for their first rides. Entry fee for the park is a couple of bucks per car. Stay of the hiking trails no matter how tempting they look (Homestead trail is a nice looking singletrack), the park is pretty well patrolled.
From Atlanta, take I-75 North, Exit 286 (I think)--just follow the "Red Top Mountain State Park" signs from the Interstate. Once in the park, stop at the office, pick up a map.
http://www.singletracks.com/item.php?c=1&i=1868