Unfortunately I believe that there are hamsters who chew the cage bars simply because they like it (like a bad habit in humans). If you
KNOW that your cage is large enough and that you provide stimulation by getting your hamster out regularly as well as other things to chew ....and your hamster
still chews on the bars then you may have to accept he's a habitual bar chewer and either let him do it or change his cage.
I had to do this - several times - it was a pain but Mocha now cannot chew any bars. He now chews on the other things provided - which he
NEVER did when the bars were there for him