The Houston bus racks have a spring-loaded arm that reaches out and over the front wheel. I position it right in front of where the fender ends, and my bike is fine.

I recommend telling the driver before you disembark that you need to get your bike. They don't always remember you, and I almost got smooshed in Ann Arbor by a driver who didn't realize I was going to take my bike off the rack. He lectured me