Does your bike have the clearance for a narrower crank? For example, I should have bought a bottom bracket spindle of about 133mm for chainline purposes on my expedition bike that uses a Rohloff. (I use square taper crank and bottom bracket.) But I wanted a narrower Q factor that was closer to the same as my derailleur bikes, so I got a 122.5mm spindle. That means that my chainline is off about 5mm, but I have no problems with chain wear.