This is a pretty straightforward park, one big loop of around 3 miles or so with nothing challenging. This is a great place to take beginners to get them comfortable on their bikes. Supposedly there is an Onion Creek trail connected here, but I've never run across it.
Location: Southeast Austin, near the airport
Directions: Take highway 183 south from Austin, past Route 71 to McKinney Falls Parkway. Follow the signs into the park
Technical Level: Easy