I got another 2 cable Grip shifter , made by another German company , with a larger diameter & a spacer to fit inside it ,
with a gap for the cable from an Aero brake cable to bass thru , under the tape..

those are made to use in Drop bar installations (will sell, Im OK with the regular one with trekking bars so don'y need it ..

would work with Nu Vinci too it and R'off are pull- pull shifted in the Hub ..

some other German Frame builders have bars that split made in the smaller 7/8" tube.. required for the standard shifter.