I always like to do a bike tour of new places as you get to see far more than on foot. We we're recommended to these guys by the W hotel concierge and booked up the day before.
We booked the 10am tour and were lucky to be the only two on the trip. Our guide was Trey (sp?) who was a local Austinite. Trey was a great guide, very knowledgable, particularly about the local outdoor art.
The tour took a couple of hours and was very hot, but the bikes were comfortable and a decent quality.
All in all a very enjoyable tour which I'd recommend highly.