Originally Posted by
cango
There is only 1.6mm difference between the road and mountain bar grip area diameter. This is dumb except to make sure you can't move parts back and forth.
What parts do you think can be moved between road and mountain bikes? Mountain brake levers and shift levers won’t work on the curved bar of a road bike. You can use road levers on flat bars if you wan’t but they aren’t optimum. Outside of not fitting well on different bars, modern mountain and road shift and brake levers aren’t compatible with the drivetrain and brake components.