I have a 2013 Specialized Allez Comp that I'm converting to a 1x8 with bullhorn handlebars and reverse brake levers. I am also wanting to mount a mountain bike 8 speed shifter on the base of the bars, next to the stem.

The problem that I've run into is that the shifters come with a 22.2mm internal clamp diameter and the reverse brake levers come with a minimum of 19mm diameter...

I've found handlebars with a 25.4mm clamp diameter, 23.8mm grip diameter where the shifter would mount, and a 19mm inner diameter where the reverse brake levers insert. The brake levers would fit right in to the ends correctly, but I would have to modify the shifter and maybe bore the clamp out 1.6mm in order for it to be able to slide on.

The other option is a 22.2mm grip diameter and an 18mm internal diameter. This is a thinner bar that will allow the shifter to just slide right on, but I would have to bore out the ends a millimeter to allow the brake levers to fit.

Which would you guys choose? Anyone run into this issue?