+1 on Measuring things..

Roller width dictates the distance between the inside of the inner link cage plates.

to pack in more gears in a finite space the whole chain has to be thinner .

so. since at 8 speed te hub axle width spread stopped .at 130. [135 on MTB]

something has to give .. thats width.

to some extent a new bike with all the latest components is a better value than buying a whole new drivetain and retrofitting it

1, 7 speed normal, is narrower rear frame width.