BB sizing

So, it's tough to figure out what BB length to use. Sheldon Brown says 52mm for chainline for a SS mountain crank. But that didn't help me figure out BB length with a triple crank, even though I'm using the middle ring. Add in the fact that I'm looking to use a tomicog at some point, so you have to figure in the 15mm distance between the inside of the dropouts and the face of the disc brake mount (6-bolt). So I used my fixie's BB even though it's a 68 shell width, not a 73, and just stuck it in one side. Lucky enough it's a 110, and after throwing on the race face crank I got off ebay, 110 seems about right for lining up with the disc brake mount. Then I'll just use a similar position on the cassette hub for freewheeling. Here's a couple pics: