gerok

I'm doing another cheap build for my daily commute. For those of you running Shimano 105's with 130bcd chainring, what BB size are you using get a 42mm chainline? I want to run the ring on the outside if it's possible.

Soil_Sampler

ring on the inside 41.5 +/- with 109.5 bb

mander

What Soil Sampler said for octalink---afaik there isn't a shorter one available. If you have some old square taper 105, you can get a 107mm bb and run your ring on the outside at 43~ mm. Slamming the crank in that close can create clearance issues depending on your frame---you'll just have to try it and see. I had to file the horizontal tabs that hold the inner ring back a mm or so on my 600s. But it does work fine now.

filtersweep

You might just try whatever BB you already have, if it is on the cheap. My quietest bike has the worst chainline--- some square taper that just happened to be in stock when I was running it with gears (attached to a Stronglight road crank). Go figure.

elTwitcho

On my roomates bike I set up a single speed drivetrain using 110mm Shimano Octalink BB and the chainline is just fine. I have never taken the time to measure it, but eyeballing it is close enough. 1 or 2 mm does not matter

mander

^^ Yes twitcho, Shimano doubles + their recommended bb generally put the inner ring at close-enough-to-42, outer ring at 46ish. The trick for people like op is to find a short enough bb and sufficient clearance to get the outer ring to 42ish.