Like said, on monty frames you can run them outside. But on some frames it has to be inside, some hubs are actually 110 spacing, each cam is 3mm thick so a pair makes up the remaining 6mm to fit in the 116mm spaced dropouts. There's some hubs thats 116mm spaced without cams, my old ZHI hub was like this I had to sand down 3mm on each side to fit cams with 10mm axle holes.