I'm building a bike for a woman who injured her hands in a fall and who now experiences pain when using trigger shifters. She does a little better with grip-shifters though even their resistance gives her trouble if she has to shift often. Does a NuVinci hub with its continuous/stepless grip-shifter have a mechanism that is easier to twist than a normal grip-shifter?
BTW, is NuVinci still in the human-powered bicycle business? Some links on their web page go to non-existent pages, and they don't have any dealers in my metro area, which has over 6 million people.