If you mean knocked over, it is a good idea to carry a small square of plywood to put under the kickstand when camping in gravel. I have had every bike I ever owned tipped over while camping. Only the first time the paint is dinged is the bad time, soon you just ignore it and it never happens again.
If you mean ripped off or stolen, that is a different color horse. A big cable to the table is the best solution. A rope tied to the bike and to the tent is another. Anything to make it noisy or difficult.
The only time I ever had one outright stolen was in a parking lot at a sporting goods store. Some character and his brother loaded it up to the back of their boat and strapped it on. I saw them do the deed and called the cops. Got the bike back, and I had more paperwork to do than they did, and spent more time at the police station dealing with the red tape than they did in jail. Next time, I will just look the other way and file a report and forget trying to stop the process.
Last edited by rcw; 08-27-2010 at 02:48 AM.