The old "Bike Cages" seem to be coming back in vogue. I remember using one at my old school back in the early 1970s. In those days, they did offer a good option against casual theft. I am not sure that it could still be done in this sort of world. A school environment is still more controlled than a public ever changing faces sort of places that public transit is. I guess nothing could be more surer than keeping your valuables next to you, or at least having a manned (with a live security guard & even a dog) secure perimeter as a bike cage is supposed to be.