While setting up a road bike recently for a friend who needed a riser stem set-up, I wanted to mount thumb shifters on top of Nitto B-135 handlebars. Nitto drop bars that have a diameter of ~23.6 mm on the stepped down section of the bar. Paul "Thumbie" shifter brackets, that allow putting Shimano bar end shifters on top of handlebars only come in two diameters, 31.8mm for road bikes or 22.2 for mountain bike handlebars.
I found a work around, by making shims from a section of a 26.8 titanium seat post cut-off then sawing a slot to get the right fit. The result is a very lightweight shim to make Paul Thumbie shifter brackets work for traditional style Nitto drop handlebars.