how to sync git repositories using redmine-git-hosting to github ?

Dear Nicolas, 

I'm trying to find the best way to synchronize repos from projects into github as backup ( read-only ). I was trying to use https://github.com/koppen/redmine_github_hook but i was not able to work with it. 
Do you have any experience or recommantations to give me about it ? 

Thanks for your help. 

BR, 
Guillaume.