Bar Biting is a common reaction to boredom. It can cause misaligned and damaged teeth and in extreme cases, the constant vibrations can cause brain damage. Often hamsters chew the bars if there is nothing else to gnaw on, no stimulation, or their cage is too small. They can become obsessed causing mental health problems and depression. If you have a cage over the recommendations, a 11″+ wheel, and plenty of things to do and they still bite the bars, then you might want to consider putting them in a tank or bin cage to stop it.
Studies have shown that “hamsters in small cages knawed significantly longer and more frequently” and that “wire gnawing might be an attempt to escape from the cage” this research can be seen on our Cages Page (insert link).