I just learned the hard way that bicycles do not stay on buses just because you have the "hook" clamped down on the front wheel. Regular buses do not bounce around as much as the rural buses. However, I only found out recently that the rear wheel can bounce out the bicycle racks of buses and cause the bicycle to flip off the rack. My bicycle bounced out of a rural bus bike rack operated by San Diego MTS. The driver stopped as soon as it flew off the bus and he did his best to avoid bumps on the road before it flew off. I was able to take pictures of the damage, although not all the damage was visible until I had the bicycle taken to a bicycle shop for repairs. I talked to an RTA rural bus driver about the accident and he recommended attaching velcro fasterners on the rear bicycle wheel. I have yet to see velcro fasteners for rear wheels on the bicycle racks of buses even though Amtrak has had them for the front and rear wheels before I started riding my bicycle for vacations.