I had CBR files I wanted to read on my iPad. I synced them, through iTunes, to GoodReader. I forgot, of course, that I use that app for reading PDFs. It doesn’t handle CBRs.
But it does allow me to upload files I have there to DropBox.
I found another app, Manga Storm CBR, which can download files from its own DropBox folder to be read locally.
So, with the help of an iPhone Personal Hotspot, I uploaded the files from GoodReader to DropBox (which allowed me to choose the App/Manga Storm CBR directory to upload the files to), and then downloaded them from there to Manga Storm CBR.
Felt a little convoluted, but I doubt we’ll see those two apps setting up share sheets for each other anytime soon. Ya never know, I suppose…