I sold my custom Mercian Vincitori tourer to buy the Thorn Raven with ROHLOFF hub. To me the idea of oem, chain tensioner et al took away from the simple elegance of the design and now I value the specific dropouts and eccentric bb which makes any maintainance so simple. For the first time ever I went for straight bars (tried the risers and impossible to get the right width for touring. I fitted stumpy barends angled forward to give me the same position as the hoods and plenty padding and this works well . With this set-up no problem with the twist grip. By the way Thorn now make a proper bar for this which fits to the stem below the drop bars. Good luck with the project.