This park has a lot of rocky terrain. There is even a homemade BMX style area where you can fly in the air like birds (just watch the low hanging branches). There is a really good single-track trail that follows a dry creek bed for miles. There are also some good drops and downhill areas for you free ride guys. The upper part of the park is a decent area for beginners but it gets a little more technical down in the lower end of the park (along of creek bed). There are usually hikers around the upper part of the park but it is usually pretty "hiker-free" in the more technical areas. A great park overall though.
In San Antonio, take IH 410 to HWY. 16 (Bandera Rd.) and go north 4.5 miles. The park entrance is on the right (there is a sign that reads, OP Schnabel Park." Once you enter the park you can either take a left into the first parking lot (the trail begins on the right side of the lot) or take a left at the first STOP sign. The parking lot is on the right (up from the pavilion). The trail head is on the right side of the parking lot (as you enter the lot).
http://www.singletracks.com/item.php?c=1&i=1490