like @Koleman says. If you are using ionic >1.1 the default scroll approach is native overflow-scrolling. This has some ups (it should be faster in most cases), but some downs (some ionic components are not working like expected aaaannnd you get the native browser handlings … like scrollbars). So in this case you can switch off overflow-scrolling on ion-contents and ion-scrolls.
Sure there is the possibility to hide the bars via css, but in most cases you need the js-scrolling functionalities