That was my first thought also.

But if you're ok with the grit, I'll just say that I when I travel with my bike, I always put it in the back of my van. I pull the front wheel and have a front fork bracket I've rigged up to allow the bike to stand and I pack around it. I've got a rear rack, but I've always had this (probably unfounded) fear of it flying off into traffic, along with one of my two-wheeled treasures. As for roof racks, I've know three other cyclists who pulled into a garage, forgetting about the bikes on top. 'Nuff said about that!