My bikes - all rim brakes. (2) 120 mm fix gears, (2) 126 mm, one a 7-speed, the other can do 7-speed or "triple chianline" fix gear. (Slightly dished doubje sided track hub with a single on one side and a double on the other. 3 chainrings and 3 very different gears. (1) 130 mm 9-speed.
I have at least two rear wheels for each of the (4) setups.
Ben