The Onion Creek Hike and Bike Trail is in McKinney Falls State Park in Southeast Austin. A paved 3-mile loop, this trail has seen better days. From the description, you might think it was a good east-side alternative to the Veloway in Southwest Austin, but the Onion Creek Trail needs a fresh coat of asphalt and is not restricted to inline skating or biking. Definitely do not bring a nice road bike here, as there are lots of cracks in the paving. Inline skaters will find this to be a tough go as well.
This trail is really nice for walking the dog, walking with a stroller, or taking the kids out on their bikes though - it's pretty and winds along Onion Creek through some walk-in campsites and picnic areas before heading through some woods and trees. There is only one steep hill on the whole trail, where you are advised to walk your bike.