Hi Mechanistas, and apologies for what feels like a fairly basic question.
Would appreciate guidance on how to identify the BB size required for my frame.
I have a never-built Look KG111 frame, for which I'm gathering bits. I would like to use a set of compact FSA Gossamer ISIS cranks and Centaur for the rest of the drive train, and wondered what size ISIS bottom bracket I'll need. I know I it needs to be English threaded, but they come in various sizes - 108 mm, 113 mm, etc.
ISIS was supposed to standardize bottom-bracket lengths, so if you're using a double crankset (I assume you mean a compact double) for proper chainline with a road (130mm-spaced) rear hub, you'll want 108mm. 113mm is for road triple (or mtb double if anyone wants to do it) and 118mm is for mtb triple.