I have an old (2000 model) sportsworks...same bike carrier that most city busses have. It is by far the best rack i have ever owned or used. Sportsworks no longer makes them for personal use (only the commercial ones for busses, etc...) and sold the patent to Thule...it's a little different (but still a great rack)... I have 3 friends with the new version by Thule and no one we know ever had any problems with them. Sometimes it does pay to spend a little extra.
Here's a link to the two bike model: http://www.thuleracks.com/product.asp?dept_id=8&sku=916
you can also add one or two more for a total ability to carry 4 bikes. The new style also accomodates tires wider than 2.5 inches (which is tougher on my rack.
Good luck!